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Space Shuttle Columbia disaster
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For further information about Columbia's mission and crew, see STS-107.
Space Shuttle Columbia disaster


STS-107 Flight Insignia.svg
STS-107 flight insignia

Time
08:59 EST (13:59 UTC)
Date
1 February 2003
Location
Over Texas and Louisiana
Outcome
Space Shuttle fleet was grounded for more than two years while safety measures were added, including procedures to deal with catastrophic cabin depressurization, better crew restraints, and an automated parachute system.
Casualties
Rick D. Husband
William C. McCool
Michael P. Anderson
Kalpana Chawla
David M. Brown
Laurel Clark
Ilan Ramon
Inquiries
Columbia Accident Investigation Board
The Space Shuttle Columbia disaster occurred on February 1, 2003, when Columbia disintegrated over Texas and Louisiana as it reentered Earth's atmosphere, killing all seven crew members.
During the launch of STS-107, Columbia's 28th mission, a piece of foam insulation broke off from the Space Shuttle external tank and struck the left wing. Most previous shuttle launches had seen minor damage from foam shedding,[1] but some engineers suspected that the damage to Columbia was more serious. NASA managers limited the investigation, reasoning that the crew could not have fixed the problem if it had been confirmed.[2]
When the Shuttle reentered the atmosphere of Earth, the damage allowed hot atmospheric gases to penetrate and destroy the internal wing structure, which caused the spacecraft to become unstable and slowly break apart.[3]
After the disaster, Space Shuttle flight operations were suspended for more than two years, similar to the aftermath of the Challenger disaster. Construction of the International Space Station (ISS) was put on hold; the station relied entirely on the Russian Federal Space Agency for resupply for 29 months until Shuttle flights resumed with STS-114 and 41 months for crew rotation until STS-121.
Several technical and organizational changes were made, including adding a thorough on-orbit inspection to determine how well the shuttle's thermal protection system had endured the ascent, and keeping a designated rescue mission ready in case irreparable damage was found. Except for one final mission to repair the Hubble Space Telescope, subsequent missions were flown only to the ISS so that the crew could use it as a "safe haven".


Contents  [hide]
1 Crew
2 Debris strike during launch
3 Flight risk management
4 Re-entry timeline
5 Presidential response
6 Recovery of debris 6.1 Crew cabin video
7 Investigation 7.1 Initial investigation
7.2 Columbia Accident Investigation Board
7.3 Conclusions
7.4 Possible emergency procedures
8 Memorials
9 Effect on space programs
10 Sociocultural aftermath 10.1 Fears of terrorism
10.2 Purple streak image
10.3 Film hoax
10.4 Music
11 See also
12 References
13 External links

Crew[edit]



 The crew of STS-107. L to R: Brown, Husband, Clark, Chawla, Anderson, McCool, RamonCommander: Rick D. Husband, a U.S. Air Force colonel and mechanical engineer, who piloted a previous shuttle during the first docking with the International Space Station (STS-96).
Pilot: William C. McCool, a U.S. Navy commander
Payload Commander: Michael P. Anderson, a U.S. Air Force lieutenant colonel and physicist who was in charge of the science mission.
Payload Specialist: Ilan Ramon, a colonel in the Israeli Air Force and the first Israeli astronaut.
Mission Specialist: Kalpana Chawla, an Indian-born aerospace engineer who was on her second space mission.
Mission Specialist: David M. Brown, a U.S. Navy captain trained as an aviator and flight surgeon. Brown worked on scientific experiments.
Mission Specialist: Laurel Blair Salton Clark, a U.S. Navy captain and flight surgeon. Clark worked on biological experiments.
Debris strike during launch[edit]



Columbia lifting off on its final mission. The light-colored triangle visible at the base of the strut near the nose of the orbiter is the Left Bipod Foam Ramp. Video


 Space Shuttle external tank foam block.


 Close-up of the Left Bipod Foam Ramp that broke off and damaged the Shuttle wing.
The shuttle's main fuel tank is covered in thermal insulation foam intended to prevent ice from forming when the tank is full of liquid hydrogen and oxygen. Such ice could damage the shuttle if shed during lift-off.
Mission STS-107 was the 113th Space Shuttle launch. Planned to begin on January 11, 2001, the mission was delayed 18 times[4] and eventually launched on January 16, 2003, following STS-113 (The Columbia Accident Investigation Board determined that this delay had nothing to do with the catastrophic failure[4]).
About 82 seconds after launch from Kennedy Space Center's LC-39-A, a suitcase-size piece of foam broke off from the External Tank (ET), striking Columbia's left wing reinforced carbon-carbon (RCC) panels. As demonstrated by ground experiments conducted by the Columbia Accident Investigation Board, this likely created a 6-to-10-inch (15 to 25 cm) diameter hole, allowing hot gases to enter the wing when Columbia later reentered the atmosphere. At the time of the foam strike, the orbiter was at an altitude of about 66,000 feet (20 km; 12.5 mi), traveling at Mach 2.46 (1,870 miles per hour or 840 meters per second).
The Left Bipod Foam Ramp is an approximately three-foot (one-meter) aerodynamic component made entirely of foam. The foam, not normally considered to be a structural material, is required to bear some aerodynamic loads. Because of these special requirements, the casting-in-place and curing of the ramps may be performed only by a senior technician.[5] The bipod ramp (having left and right sides) was originally designed to reduce aerodynamic stresses around the bipod attachment points at the external tank, but it was proven unnecessary in the wake of the accident and was removed from the external tank design for tanks flown after STS-107 (another foam ramp along the liquid oxygen line was also later removed from the tank design to eliminate it as a foam debris source, after complex analysis and tests proved this change safe).
Bipod Ramp insulation had been observed falling off, in whole or in part, on four previous flights: STS-7 (1983), STS-32 (1990), STS-50 (1992) and most recently STS-112 (just two launches before STS-107). All affected shuttle missions completed successfully. NASA management came to refer to this phenomenon as "foam shedding". As with the O-ring erosion problems that ultimately doomed the Space Shuttle Challenger, NASA management became accustomed to these phenomena when no serious consequences resulted from these earlier episodes. This phenomenon was termed "normalization of deviance" by sociologist Diane Vaughan in her book on the Challenger launch decision process.[6]
As it happened, STS-112 had been the first flight with the "ET Cam", a video feed mounted on the ET for the purpose of giving greater insight to the foam shedding problem. During that launch a chunk of foam broke away from the ET bipod ramp and hit the SRB-ET Attach Ring near the bottom of the left solid rocket booster (SRB) causing a dent four inches wide and three inches deep in it.[7] After STS-112, NASA leaders analyzed the situation and decided to press ahead under the justification that "The ET is safe to fly with no new concerns (and no added risk)" of further foam strikes.[8]
Video taken during lift-off of STS-107 was routinely reviewed two hours later and revealed nothing unusual. The following day, higher-resolution film that had been processed overnight revealed the foam debris striking the left wing, potentially damaging the thermal protection on the Space Shuttle.[9] At the time, the exact location where the foam struck the wing could not be determined due to the low resolution of the tracking camera footage.
Meanwhile, NASA's judgement about the risks was revisited. Chair of the Mission Management Team (MMT) Linda Ham said the “Rationale was lousy then and still is”. Ham and Shuttle Program Manager Ron Dittemore had both been present at the October 31, 2002, meeting where the decision to continue with launches was made.[10]
Post-107 analysis revealed that two previous shuttle launches (STS-52 and -62) also had bipod ramp foam loss that went undetected. In addition, Protuberance Air Load (PAL) ramp foam had also shed pieces, and there were also spot losses from large-area foams.
Flight risk management[edit]
In a risk-management scenario similar to the Challenger disaster, NASA management failed to recognize the relevance of engineering concerns for safety for imaging to inspect possible damage, and failed to respond to engineer requests about the status of astronaut inspection of the left wing. Engineers made three separate requests for Department of Defense (DOD) imaging of the shuttle in orbit to more precisely determine damage. While the images were not guaranteed to show the damage, the capability existed for imaging of sufficient resolution to provide meaningful examination. NASA management did not honor the requests and in some cases intervened to stop the DOD from assisting.[11] The CAIB recommended subsequent shuttle flights be imaged while in orbit using ground-based or space-based DOD assets.[12] Details of the DOD's unfulfilled participation with Columbia remain secret; retired NASA official Wayne Hale stated in 2012 that "Activity regarding other national assets and agencies remains classified and I cannot comment on that aspect of the Columbia tragedy".[13]
Throughout the risk assessment process, senior NASA managers were influenced by their belief that nothing could be done even if damage was detected. This affected their stance on investigation urgency, thoroughness and possible contingency actions. They decided to conduct a parametric "what-if" scenario study more suited to determine risk probabilities of future events, instead of inspecting and assessing the actual damage. The investigation report in particular singled out NASA manager Linda Ham for exhibiting this attitude.[14] In 2013, Hale recalled that Director of Mission Operations John Harpold told him before Columbia's destruction:

You know, there is nothing we can do about damage to the TPS [Thermal Protection System]. If it has been damaged it's probably better not to know. I think the crew would rather not know. Don't you think it would be better for them to have a happy successful flight and die unexpectedly during entry than to stay on orbit, knowing that there was nothing to be done, until the air ran out?[15]
Hale added, "I was hard pressed to disagree [at the time]. That mindset was widespread. Astronauts agreed. So don't blame an individual; look for the organizational factors that lead to that kind of a mindset. Don't let them in your organization".[15]
Much of the risk assessment hinged on damage predictions to the thermal protection system. These fall into two categories: damage to the silica tile on the wing lower surface, and damage to the reinforced carbon-carbon (RCC) leading-edge panels (The TPS includes a third category of components: thermal insulating blankets; but damage predictions are not typically performed on them. Damage assessments on the thermal blankets can be performed after an anomaly has been observed, and this has been done at least once after the return to flight following Columbia's loss).
Before the flight NASA believed that the RCC was very durable. Charles F. Bolden, who worked on tile-damage scenarios and repair methods early in his astronaut career, said in 2004 that[16]

never did we talk about [the RCC] because we all thought that it was impenetrable ... I spent fourteen years in the space program flying, thinking that I had this huge mass that was about five or six inches thick on the leading edge of the wing. And, to find after Columbia that it was fractions of an inch thick, and that it wasn't as strong as the Fiberglas on your Corvette, that was an eye-opener, and I think for all of us ... the best minds that I know of, in and outside of NASA, never envisioned that as a failure mode.
Damage-prediction software was used to evaluate possible tile and RCC damage. The tool for predicting tile damage was known as "Crater", described by several NASA representatives in press briefings as not actually a software program but rather a statistical spreadsheet of observed past flight events and effects. The "Crater" tool predicted severe penetration of multiple tiles by the impact if it struck the TPS tile area, but NASA engineers downplayed this. The engineers believed that results showing that the model overstated damage from small projectiles meant that the same would be true of larger Spray-On Foam Insulation (SOFI) impacts. The program used to predict RCC damage was based on small ice impacts the size of cigarette butts, not larger SOFI impacts, as the ice impacts were the only recognized threats to RCC panels up to that point. Under 1 of 15 predicted SOFI impact paths, the software predicted an ice impact would completely penetrate the RCC panel. Engineers downplayed this, too, believing that impacts of the less dense SOFI material would result in less damage than ice impacts. In an e-mail exchange, NASA managers questioned whether the density of the SOFI could be used as justification for reducing predicted damage. Despite engineering concerns about the energy imparted by the SOFI material, NASA managers ultimately accepted the rationale to reduce predicted damage of the RCC panels from possible complete penetration to slight damage to the panel's thin coating.[17]
Ultimately the NASA Mission Management Team felt there was insufficient evidence to indicate that the strike was an unsafe situation, so they declared the debris strike a "turnaround" issue (not of highest importance) and denied the requests for the Department of Defense images.
On January 23, flight director Steve Stich sent an e-mail to Columbia, informing commander Husband and pilot McCool of the foam strike while unequivocally dismissing any concerns about entry safety.[18][19]

During ascent at approximately 80 seconds, photo analysis shows that some debris from the area of the -Y ET Bipod Attach Point came loose and subsequently impacted the orbiter left wing, in the area of transition from Chine to Main Wing, creating a shower of smaller particles. The impact appears to be totally on the lower surface and no particles are seen to traverse over the upper surface of the wing. Experts have reviewed the high speed photography and there is no concern for RCC or tile damage. We have seen this same phenomenon on several other flights and there is absolutely no concern for entry.[20]
Re-entry timeline[edit]
Columbia was scheduled to land at 9:16 a.m. EST.
2:30 a.m. EST, February 1, 2003: The Entry Flight Control Team began duty in the Mission Control Center.
The Flight Control Team had not been working on any issues or problems related to the planned de-orbit and re-entry of Columbia. In particular, the team had indicated no concerns about the debris that hit the left wing during ascent, and treated the re-entry like any other. The team worked through the de-orbit preparation checklist and re-entry checklist procedures. Weather forecasters, with the help of pilots in the Shuttle Training Aircraft, evaluated landing-site weather conditions at the Kennedy Space Center.8:00: Mission Control Center Entry Flight Director LeRoy Cain polled the Mission Control room for a GO/NO-GO decision for the de-orbit burn.
All weather observations and forecasts were within guidelines set by the flight rules, and all systems were normal.8:10: The Capsule Communicator (CAPCOM) told the crew that they were GO for de-orbit burn.
8:15:30 (EI-1719): Husband and McCool executed the de-orbit burn using Columbia’s two Orbital Maneuvering System engines.
The Orbiter was upside down and tail-first over the Indian Ocean at an altitude of 175 miles (282 km) and speed of 17,500 miles per hour (7.8 km/s) when the burn was executed. A 2-minute, 38-second de-orbit burn during the 255th orbit slowed the Orbiter to begin its re-entry into the atmosphere. The burn proceeded normally, putting the crew under about one-tenth gravity. Husband then turned Columbia right side up, facing forward with the nose pitched up.8:44:09 (EI+000): Entry Interface (EI), arbitrarily defined as the point at which the Orbiter entered the discernible atmosphere at 400,000 feet (120 km; 76 mi), occurred over the Pacific Ocean.
As Columbia descended, the heat of reentry caused wing leading-edge temperatures to rise steadily, reaching an estimated 2,500 °F (1,370 °C) during the next six minutes (As former Space Shuttle Program Manager Wayne Hale said in a press briefing, about 90% of this heating is the result of compression of the atmospheric gas caused by the orbiter's supersonic flight, rather than the result of friction).


Columbia at about 8:57. Debris is visible coming from the left wing (bottom). The image was taken at Starfire Optical Range at Kirtland Air Force Base.8:48:39 (EI+270): A sensor on the left wing leading edge spar showed strains higher than those seen on previous Columbia re-entries.
This was recorded only on the Modular Auxiliary Data System, which is similar in concept to a flight data recorder, and was not sent to ground controllers or shown to the crew.8:49:32 (EI+323): Columbia executed a planned roll to the right. Speed: Mach 24.5.
Columbia began a banking turn to manage lift and therefore limit the Orbiter's rate of descent and heating.8:50:53 (EI+404): Columbia entered a 10-minute period of peak heating, during which the thermal stresses were at their maximum. Speed: Mach 24.1; altitude: 243,000 feet (74 km; 46.0 mi).
8:52:00 (EI+471): Columbia was about 300 miles (480 km) west of the California coastline.
The wing leading-edge temperatures usually reached 2,650 °F (1,450 °C) at this point.8:53:26 (EI+557): Columbia crossed the California coast west of Sacramento. Speed: Mach 23; altitude: 231,600 feet (70.6 km; 43.86 mi).



Columbia debris (in red, orange, and yellow) detected by National Weather Service radar over Texas and Louisiana.The Orbiter's wing leading edge typically reached more than 2,800 °F (1,540 °C) at this point.8:53:46 (EI+577): Various people on the ground saw signs of debris being shed. Speed: Mach 22.8; altitude: 230,200 feet (70.2 km; 43.60 mi).
The superheated air surrounding the Orbiter suddenly brightened, causing a streak in the Orbiter's luminescent trail that was quite noticeable in the pre-dawn skies over the West Coast. Observers witnessed four similar events during the following 23 seconds. Dialogue on some of the amateur footage indicates the observers were aware of the abnormality of what they were filming.8:54:24 (EI+615): The Maintenance, Mechanical, and Crew Systems (MMACS) officer told the Flight Director that four hydraulic sensors in the left wing were indicating "off-scale low". In Mission Control, re-entry had been proceeding normally up to this point.
"Off-scale low" is a reading that falls below the minimum capability of the sensor, and it usually indicates that the sensor has stopped functioning, due to internal or external factors, not that the quantity it measures is actually below the sensor's minimum response value.8:54:25 (EI+616): Columbia crossed from California into Nevada airspace. Speed: Mach 22.5; altitude: 227,400 feet (69.3 km; 43.07 mi).
Witnesses observed a bright flash at this point and 18 similar events in the next four minutes.8:55:00 (EI+651): Nearly 11 minutes after Columbia re-entered the atmosphere, wing leading-edge temperatures normally reached nearly 3,000 °F (1,650 °C).
8:55:32 (EI+683): Columbia crossed from Nevada into Utah. Speed: Mach 21.8; altitude: 223,400 feet (68.1 km; 42.31 mi).
8:55:52 (EI+703): Columbia crossed from Utah into Arizona.
8:56:30 (EI+741): Columbia began a roll reversal, turning from right to left over Arizona.
8:56:45 (EI+756): Columbia crossed from Arizona to New Mexico. Speed: Mach 20.9; altitude: 219,000 feet (67 km; 41.5 mi).
8:57:24 (EI+795): Columbia passed just north of Albuquerque.
8:58:00 (EI+831): At this point, wing leading-edge temperatures typically decreased to 2,880 °F (1,580 °C).
8:58:20 (EI+851): Columbia crossed from New Mexico into Texas. Speed: Mach 19.5; altitude: 209,800 feet (63.9 km; 39.73 mi).
At about this time, the Orbiter shed a Thermal Protection System tile, the most westerly piece of debris that has been recovered. Searchers found the tile in a field in Littlefield, Texas, just northwest of Lubbock.8:59:15 (EI+906): MMACS told the Flight Director that pressure readings had been lost on both left main landing-gear tires. The Flight Director then instructed the Capsule Communicator (CAPCOM) to let the crew know that Mission Control saw the messages and was evaluating the indications, and added that the Flight Control Team did not understand the crew's last transmission.
8:59:32 (EI+923): A broken response from the mission commander was recorded: "Roger, uh, bu – [cut off in mid-word] ..." It was the last communication from the crew and the last telemetry signal received in Mission Control.
8:59:37 (EI+928): Hydraulic pressure, which is required to move the flight control surfaces, was lost at about 8:59:37. At that time, the Master Alarm would have sounded for the loss of hydraulics, and the shuttle began to lose control, beginning to roll and yaw uncontrollably, and the crew would have become aware of the serious problem.[21]
9:00:18 (EI+969): Videos and eyewitness reports by observers on the ground in and near Dallas indicated that the Orbiter had disintegrated overhead, continued to break up into more and smaller pieces, and left multiple contrails, as it continued eastward. In Mission Control, while the loss of signal was a cause for concern, there was no sign of any serious problem. Before the orbiter broke up at 9:00:18, the Columbia cabin pressure was nominal and the crew was capable of conscious actions.[21] The crew module remained mostly intact through the breakup, though it was damaged enough that it lost pressure at a rate fast enough to incapacitate the crew within seconds,[22] and was completely depressurized no later than 9:00:53.
9:00:57 (EI+1008): The crew module, intact to this point, was seen breaking into small subcomponents. It disappeared from view at 9:01:10. The crew, if not already dead, were killed no later than this point.
9:05: Residents of north central Texas, particularly near Tyler, reported a loud boom, a small concussion wave, smoke trails and debris in the clear skies above the counties east of Dallas.
9:12:39 (EI+1710): After hearing of reports of the shuttle being seen to break apart, Entry Flight Director LeRoy Cain declared a contingency (events leading to loss of the vehicle) and alerted search-and-rescue teams in the debris area. He called on the Ground Controller to "lock the doors". Two minutes later, Mission Control put contingency procedures into effect. Nobody was permitted to enter or leave the room, and flight controllers had to preserve all the mission data for later investigation.[23]
Presidential response[edit]










 President George W. Bush's address on the Columbia's destruction, February 1, 2003.
At 14:04 EST (19:04 UTC), President George W. Bush said, "This day has brought terrible news and great sadness to our country ... The Columbia is lost; there are no survivors". Despite the disaster, Bush said, "The cause in which they died will continue....Our journey into space will go on".[24] Bush later declared East Texas a federal disaster area, allowing federal agencies to help with the recovery effort.[25]
Recovery of debris[edit]



 Grid on a floor
More than 2,000 debris fields were found in sparsely populated areas from Nacogdoches in East Texas, where a large amount of debris fell, to western Louisiana and the southwestern counties of Arkansas. One debris field has been mapped along a path stretching from south of Fort Worth to Hemphill, Texas, as well as into parts of Louisiana.[26] Various notable places that had debris included Stephen F. Austin State University in Nacogdoches and several casinos in Shreveport, Louisiana.[26] Along with pieces of the shuttle and bits of equipment, searchers also found human body parts, including arms, feet, a torso, a skull, and a heart.[27]
In the months after the disaster, the largest-ever organized ground search took place.[28] NASA issued warnings to the public that any debris could contain hazardous chemicals, that it should be left untouched, its location reported to local emergency services or government authorities, and that anyone in unauthorized possession of debris would be prosecuted. Because of the widespread area, volunteer amateur radio operators accompanied the search teams to provide communications support.[29]
A group of small (1 mm) adult Caenorhabditis elegans worms, living in petri dishes enclosed in aluminum canisters, survived re-entry and impact with the ground and were recovered weeks after the disaster.[30][31] The culture was found to be alive on April 28, 2003.[32] The worms were part of a biological research in canisters experiment designed to study the effect of weightlessness on physiology; the experiment was conducted by Cassie Conley, NASA's current Planetary protection officer.[citation needed]
Debris Search Pilot Jules F. Mier Jr. and Debris Search Aviation Specialist Charles Krenek died in a helicopter crash that injured three others during the search.[33]
Some Texas residents recovered some of the debris, ignoring the warnings, and attempted to sell it on the online auction site eBay, starting at $10,000. The auction was quickly removed, but prices for Columbia merchandise such as programs, photographs and patches, went up dramatically following the disaster, creating a surge of Columbia-related listings.[34] A three-day amnesty offered for "looted" shuttle debris brought in hundreds of illegally recovered pieces.[35] About 40,000 recovered pieces of debris have never been identified. The largest pieces recovered include the front landing gear,[36] and a window frame.[37]



 The glow of reentry as seen out the front windows.
On May 9, 2008, it was reported that data from a disk drive on board Columbia had survived the shuttle accident, and while part of the 340 MB drive was damaged, 99% of the data was recovered.[38] The drive was used to store data from an experiment on the properties of shear thinning.[39]
On July 29, 2011, Nacogdoches authorities told NASA that a 4-foot (1.2 m) diameter piece of debris had been found in a lake. NASA identified the piece as a "PRSD: power reactant storage and distribution".[40]
All recovered non-human Columbia debris is stored in unused office space at the Vehicle Assembly Building, except for parts of the crew compartment, which are kept separate.[41]
Crew cabin video[edit]


File:STS-107, final moments in cabin (Space Shuttle Columbia disaster).webm
Play media


 Video of the final moments as filmed by the crew.
Among the recovered items was a videotape recording made by the astronauts during the start of re-entry. The 13-minute recording shows the flight crew astronauts conducting routine re-entry procedures and joking with each other. None gives any indication of a problem. In the video, the flight-deck crew puts on their gloves and passes the video camera around to record plasma and flames visible outside the windows of the orbiter (a normal occurrence). The recording, which on normal flights would have continued through landing, ends about four minutes before the shuttle began to disintegrate and 11 minutes before Mission Control lost the signal from the orbiter.[42]
Investigation[edit]
Initial investigation[edit]



 A mock-up of a space shuttle leading edge made with an RCC-panel taken from Discovery. Simulation of known and possible conditions of the foam impact on Columbia's final launch showed Brittle fracture of RCC.
NASA Space Shuttle Program Manager Ron Dittemore reported that "The first indication was loss of temperature sensors and hydraulic systems on the left wing. They were followed seconds and minutes later by several other problems, including loss of tire pressure indications on the left main gear and then indications of excessive structural heating".[43] Analysis of 31 seconds of telemetry data which had initially been filtered out because of data corruption within it showed the shuttle fighting to maintain its orientation, eventually using maximum thrust from its Reaction Control System jets.
The investigation focused on the foam strike from the very beginning. Incidents of debris strikes from ice and foam causing damage during take-off were already well known, and had damaged orbiters, most noticeably during STS-45, STS-27, and STS-87.[44] After the loss of Columbia, NASA concluded that mistakes during installation were the likely cause of foam loss, and retrained employees at Michoud Assembly Facility in Louisiana to apply foam without defects.[13] Tile damage had also been traced to ablating insulating material from the cryogenic fuel tank in the past. The composition of the foam insulation had been changed in 1997 to exclude the use of freon, a chemical that is suspected to cause ozone depletion; while NASA was exempted from legislation phasing out CFCs, the agency chose to change the foam nonetheless. STS-107 used an older "lightweight tank" (a design that was succeeded by the "superlightweight tank", both being upgrades from the original space shuttle external tank) where the foam was sprayed on to the larger cylindrical surfaces using the newer freon-free foam. However, the bipod ramps were manufactured from BX-250 foam which was excluded from the EPA regulations and did use the original freon formula. The composition change did not contribute to the accident.[45] In any case, the original formulation had shown frequent foam losses, as discussed earlier in this article.
Columbia Accident Investigation Board[edit]
Main article: Columbia Accident Investigation Board
Following protocols established after the loss of Challenger, an independent investigating board was created immediately after the accident. The Columbia Accident Investigation Board, or CAIB, was chaired by retired US Navy Admiral Harold W. Gehman, Jr.,[46] and consisted of expert military and civilian analysts who investigated the accident in detail.



Columbia's flight data recorder
Columbia's flight data recorder was found near Hemphill, Texas, on March 19, 2003.[47] Unlike commercial jet aircraft, the space shuttles did not have flight data recorders intended for after-crash analysis. Instead, the vehicle data were transmitted in real time to the ground via telemetry. Since Columbia was the first shuttle, it had a special flight data OEX (Orbiter EXperiments) recorder, designed to help engineers better understand vehicle performance during the first test flights. After the initial Shuttle test-flights were completed, the recorder was never removed from Columbia, and it was still functioning on the crashed flight. It recorded many hundreds of parameters, and contained very extensive logs of structural and other data, which allowed the CAIB to reconstruct many of the events during the process leading to breakup.[48] Investigators could often use the loss of signals from sensors on the wing to track how the damage progressed.[49] This was correlated with forensic debris analysis conducted at Lehigh University and other tests to obtain a final conclusion about the probable course of events.[50]
Beginning on May 30, 2003, foam impact tests were performed by Southwest Research Institute. They used a compressed air gun to fire a foam block of similar size and mass to that which struck Columbia, at the same estimated speed. To represent the leading edge of Columbia's left wing, RCC panels from NASA stock, along with the actual leading-edge panels from Enterprise, which were fiberglass, were mounted to a simulating structural metal frame. At the beginning of testing, the likely impact site was estimated to be between RCC panel 6 and 9, inclusive. Over many days, dozens of the foam blocks were shot at the wing leading edge model at various angles. These produced only cracks or surface damage to the RCC panels.
During June, further analysis of information from Columbia's flight data recorder narrowed the probable impact site to one single panel: RCC wing panel 8. On July 7, in a final round of testing, a block fired at the side of an RCC panel 8 created a hole 16 by 16.7 inches (41 by 42 cm) in that protective RCC panel.[51] The tests demonstrated that a foam impact of the type Columbia sustained could seriously breach the thermal protection system on the wing leading edge.[52]
Conclusions[edit]
On August 26, the CAIB issued its report on the accident. The report confirmed the immediate cause of the accident was a breach in the leading edge of the left wing, caused by insulating foam shed during launch. The report also delved deeply into the underlying organizational and cultural issues that led to the accident. The report was highly critical of NASA's decision-making and risk-assessment processes. It concluded the organizational structure and processes were sufficiently flawed and that a compromise of safety was expected no matter who was in the key decision-making positions. An example was the position of Shuttle Program Manager, where one individual was responsible for achieving safe, timely launches and acceptable costs, which are often conflicting goals. The CAIB report found that NASA had accepted deviations from design criteria as normal when they happened on several flights and did not lead to mission-compromising consequences. One of those was the conflict between a design specification stating that the thermal protection system was not designed to withstand significant impacts and the common occurrence of impact damage to it during flight. The board made recommendations for significant changes in processes and organizational culture.
On December 30, 2008, NASA released a further report, entitled Columbia Crew Survival Investigation Report, produced by a second commission, the Spacecraft Crew Survival Integrated Investigation Team (SCSIIT). NASA had commissioned this group, "to perform a comprehensive analysis of the accident, focusing on factors and events affecting crew survival, and to develop recommendations for improving crew survival for all future human space flight vehicles."[53] The report concluded that: "The Columbia depressurization event occurred so rapidly that the crew members were incapacitated within seconds, before they could configure the suit for full protection from loss of cabin pressure. Although circulatory systems functioned for a brief time, the effects of the depressurization were severe enough that the crew could not have regained consciousness. This event was lethal to the crew".
The report also concluded:
The crew did not have time to prepare themselves. Some crew members were not wearing their safety gloves, and one crew member was not wearing a helmet. New policies gave the crew more time to prepare for descent.
The crew's safety harnesses malfunctioned during the violent descent. The harnesses on the three remaining shuttles were upgraded after the accident.
The key recommendations of the report included that future spacecraft crew survival systems should not rely on manual activation to protect the crew.[54]
Possible emergency procedures[edit]
The CAIB determined that a rescue mission, though risky, might have been possible provided NASA management had taken action soon enough.[55][56] They stated that, had NASA management acted in time, two possible contingency procedures were available: a rescue mission by shuttle Atlantis, and an emergency spacewalk to attempt repairs to the left wing thermal protection.
Normally, a rescue mission is not possible, due to the time required to prepare a shuttle for launch, and the limited consumables (power, water, air) of an orbiting shuttle. However, Atlantis was well along in processing for a planned March 1 launch on STS-114, and Columbia carried an unusually large quantity of consumables due to an Extended Duration Orbiter package. The CAIB determined that this would have allowed Columbia to stay in orbit until flight day 30 (February 15). NASA investigators determined that Atlantis processing could have been expedited with no skipped safety checks for a February 10 launch. Hence, if nothing went wrong, there was a five-day overlap for a possible rescue. As mission control could deorbit an empty shuttle, but could not control the orbiter's reentry and landing, it would likely have sent Columbia into the Pacific Ocean;[56] NASA later developed the Remote Control Orbiter system to permit mission control to land a shuttle. Docking at the International Space Station for use as a haven while awaiting rescue (or to use the Soyuz to systematically ferry the crew to safety) would have been impossible due to the different orbital inclination of the vehicles.
NASA investigators determined that on-orbit repair by the shuttle astronauts was possible but overall considered "high risk", primarily due to the uncertain resiliency of the repair using available materials and the anticipated high risk of doing additional damage to the Orbiter.[55][56] Columbia did not carry the Canadarm, or Remote Manipulator System, which would normally be used for camera inspection or transporting a spacewalking astronaut to the wing. Therefore, an unusual emergency extra-vehicular activity (EVA) would have been required. While there was no astronaut EVA training for maneuvering to the wing, astronauts are always prepared for a similarly difficult emergency EVA to close the external tank umbilical doors located on the orbiter underside, which is necessary for reentry. Similar methods could have reached the shuttle left wing for inspection or repair.[56]
For the repair, the CAIB determined that the astronauts would have to use tools and small pieces of titanium, or other metal, scavenged from the crew cabin. These metals would help protect the wing structure and would be held in place during re-entry by a water-filled bag that had turned into ice in the cold of space. The ice and metal would help restore wing leading edge geometry, preventing a turbulent airflow over the wing and therefore keeping heating and burn-through levels low enough for the crew to survive re-entry and bail out before landing. The CAIB could not determine whether a patched-up left wing would have survived even a modified re-entry, and concluded that the rescue option would have had a considerably higher chance of bringing Columbia's crew back alive.[55][56]
Memorials[edit]
On February 4, 2003, President George W. Bush and his wife Laura led a memorial service for the astronauts' families at the Lyndon B. Johnson Space Center. Two days later, Vice President Dick Cheney and his wife Lynne led a similar service at Washington National Cathedral. Patti LaBelle sang "Way Up There" as part of the service.[57]



 A makeshift memorial at the main entrance to the Lyndon B. Johnson Space Center in Houston, Texas


Columbia Memorial in Arlington National Cemetery


Columbia memorial on Mars Exploration Rover "Spirit"


 Space Shuttle Columbia memorial - Sabine County, Texas
On February 2, large memorial Catholic Brazilian masses were held in Rio de Janeiro and Sao Paulo, where Brazilian Catholic priest Marcelo Rossi and his concert partner Belo sang "Noites Traicoeiras (Treacherous Nights)" as tribute to the seven Columbia astronauts as well as the other seven astronauts who lost their lives in the other space shuttle in the 1986 Space Shuttle Challenger disaster. At Rio de Janeiro's famous Copacabana Beach, a large Roman Catholic memorial concert, attended by an estimated 1,100 Brazilian citizens, took place. Father Marcelo Rossi and the thousand-plus strong Brazilian audience performed the tribute song "Noites Traicoeiras" (Treacherous Nights) in honor of Space Shuttle Columbia and her crew, his partner Belo appeared live via Skype on large screens at the Columbia Memorial Concert and sang "Noites Traicoeiras" along with Father Rossi and the massive crowd of Brazilian people.
On March 26, the United States House of Representatives' Science Committee approved funds for the construction of a memorial at Arlington National Cemetery for the STS-107 crew. A similar memorial was built at the cemetery for the last crew of Challenger. On October 28, 2003, the names of the astronauts were added to the Space Mirror Memorial at the Kennedy Space Center Visitor Complex.
The Houston Astros, who reside in the same city as Johnson Space Center and whose team name honors the U.S. space program, honored the crew on April 1, 2003, the Opening Day of the season, by having seven simultaneous first pitches thrown by family and friends of the Columbia crew. For the National Anthem, 107 NASA personnel, including flight controllers and others involved in Columbia's final mission, carried a U.S. flag onto the field. In addition, the Astros wore the mission patch on their sleeves and replaced all dugout advertising with the mission patch logo for the entire season.[58]
In 2004, Bush conferred posthumous Congressional Space Medals of Honor to all 14 astronauts lost in the Challenger and Columbia accidents.[59]
NASA named several places in honor of Columbia and the crew. Seven asteroids discovered in July 2001 at the Mount Palomar observatory were officially given the names of the seven astronauts: 51823 Rickhusband, 51824 Mikeanderson, 51825 Davidbrown, 51826 Kalpanachawla, 51827 Laurelclark, 51828 Ilanramon, 51829 Williemccool.[60] On Mars, the landing site of the rover Spirit was named Columbia Memorial Station, and included a memorial plaque to the Columbia crew mounted on the back of the high gain antenna. A complex of seven hills east of the Spirit landing site was dubbed the Columbia Hills; each of the seven hills was individually named for a member of the crew, and Husband Hill in particular was ascended and explored by the rover. In 2006, the IAU approved naming of a cluster of seven small craters in the Apollo basin on the Far side of the Moon after the astronauts.[61] Back on Earth, NASA's National Scientific Balloon Facility was renamed the Columbia Scientific Balloon Facility.
Other tributes included the decision by Amarillo, Texas, to rename its airport Rick Husband Amarillo International Airport after the Amarillo native. State Route 904 was renamed Lt. Michael P. Anderson Memorial Highway, as it runs through Cheney, Washington, the town where he graduated from high school. A newly constructed elementary school located on Fairchild Air Force Base near Spokane, Washington, was named Michael Anderson Elementary School. Anderson had attended fifth grade at Blair Elementary, the base's previous elementary school, while his father was stationed there. A mountain peak near Kit Carson Peak and Challenger Point in the Sangre de Cristo Range was renamed Columbia Point, and a dedication plaque was placed on the point in August, 2003. Seven dormitories were named in honor of Columbia crew members at the Florida Institute of Technology, Creighton University, The University of Texas at Arlington, and the Columbia Elementary School in the Brevard County School District. The Huntsville City Schools in Huntsville, Alabama, a city strongly associated with NASA, named their most recent high school Columbia High School as a memorial to the crew. A Department of Defense school in Guam was renamed Commander William C. McCool Elementary School.[62] The City of Palmdale, California, the birthplace of the entire shuttle fleet, changed the name of the thoroughfare Avenue M to Columbia Way. In Avondale, Arizona, the Avondale Elementary School where Michael Anderson's sister worked had sent a t-shirt with him into space. It was supposed to have an assembly when he returned from space. The school was later renamed Michael Anderson Elementary.
 In October, 2004, both houses of Congress passed a resolution authored by US Representative Lucille Roybal-Allard and co-sponsored by the entire contingent of California representatives to Congress changing the name of Downey, California's Space Science Learning Center to the Columbia Memorial Space Science Learning Center. The facility is located at the former manufacturing site of the space shuttles, including Columbia and Challenger.[63]
The US Air Force's Squadron Officer School at Maxwell Air Force Base, Alabama, renamed their auditorium in Husband's honor. He was a graduate of the program. The US Test Pilot School at Edwards Air Force Base in California named its pilot lounge for Husband.
NASA named a supercomputer "Columbia" in the crew's honor in 2004. It was located at the NASA Advanced Supercomputing Division at Ames Research Center on Moffett Federal Airfield near Mountain View, California. The first part of the system, built in 2003, known as "Kalpana" was dedicated to Chawla, who worked at Ames prior to joining the Space Shuttle program.[64] On February 5, 2003, the space agency of India, ISRO, renamed one of its meteorological satellites METSAT Kalpana-1 on the orders of Prime Minister Atal Bihari Vajpayee.
A US Navy compound at a major coalition military base in Afghanistan is named Camp McCool. In addition, the athletic field at McCool's alma mater, Coronado High School in Lubbock, Texas, was renamed the Willie McCool Track and Field.
A proposed reservoir in Cherokee County in Eastern Texas is to be named Lake Columbia.[65]
Ilan Ramon High School was established in 2006 in Hod HaSharon, Israel, in tribute to the first Israeli astronaut.[66] The school's symbol shows the planet Earth with an aircraft orbiting around it.[67]
The National Naval Medical Center dedicated Laurel Clark Memorial Auditorium on July 11, 2003.[68] Gamma Phi Beta sorority, of which Clark was a member, created the Laurel Clark Foundation in her honor.[69]
PS 58 in Staten Island, New York, was named Space Shuttle Columbia School in honor of the failed mission.[70]
Effect on space programs[edit]
Following the loss of Columbia, the space shuttle program was suspended.[49] The further construction of the International Space Station (ISS) was also delayed, as the space shuttles were the only available delivery vehicle for station modules. The station was supplied using Russian unmanned Progress ships, and crews were exchanged using Russian-manned Soyuz spacecraft, and forced to operate on a skeleton crew of two.[71][72]
Less than a year after the accident, President Bush announced the Vision for Space Exploration, calling for the space shuttle fleet to complete the ISS, with retirement by the year 2010 following the completion of the ISS, to be replaced by a newly developed Crew Exploration Vehicle for travel to lunar orbit and landing and to Mars.[73] NASA planned to return the space shuttle to service around September 2004; that date was pushed back to July 2005.
On July 26, 2005, at 10:39 am EST, Space Shuttle Discovery cleared the tower on the "Return to Flight" mission STS-114, marking the shuttle's return to space. Overall the STS-114 flight was highly successful, but a similar piece of foam from a different portion of the tank was shed, although the debris did not strike the Orbiter. Due to this, NASA once again grounded the shuttles until the remaining problem was understood and a solution implemented.[49] After delaying their re-entry by two days due to adverse weather conditions, Commander Eileen Collins and Pilot James M. Kelly returned Discovery safely to Earth on August 9, 2005. Later that same month, the external tank construction site at Michoud was damaged by Hurricane Katrina.[74] At the time, there was concern that this would set back further shuttle flights by at least two months and possibly more.
The actual cause of the foam loss on both Columbia and Discovery was not determined until December 2005, when x-ray photographs of another tank showed that thermal expansion and contraction during filling, not human error, caused cracks that led to foam loss. NASA's Hale formally apologized to the Michoud workers who had been blamed for the loss of Columbia for almost three years.[13]
The second "Return to Flight" mission, STS-121, launched on July 4, 2006, at 2:37:55 pm (EDT), after two previous launches were scrubbed because of lingering thunderstorms and high winds around the launch pad. The launch took place despite objections from its chief engineer and safety head. This mission increased the ISS crew to three. A 5-inch (130 mm) crack in the foam insulation of the external tank gave cause for concern; however, the Mission Management Team gave the go for launch.[75] Space Shuttle Discovery touched down successfully on July 17, 2006 at 9:14:43 am (EDT) on Runway 15 at the Kennedy Space Center.
On August 13, 2006, NASA announced that STS-121 had shed more foam than they had expected. While this did not delay the launch for the next mission, STS-115, originally set to lift off on August 27,[76] the weather and other technical glitches did, with a lightning strike, Hurricane Ernesto and a faulty fuel tank sensor combining to delay the launch until September 9. On September 19, landing was delayed an extra day to examine Atlantis after objects were found floating near the shuttle in the same orbit. When no damage was detected, Atlantis landed successfully on September 21.
The Columbia Crew Survival Investigation Report released by NASA on December 30, 2008, made further recommendations to improve a crew's survival chances on future space vehicles, such as the (planned) Orion spacecraft. These include improvements in crew restraints, finding ways to deal more effectively with catastrophic cabin depressurization, more "graceful degradation" of vehicles during a disaster so that crews will have a better chance at survival, and automated parachute systems.[53]
Sociocultural aftermath[edit]
Fears of terrorism[edit]
After the shuttle's breakup, there were some initial fears that terrorists might have been involved, but no evidence of that has ever surfaced.[77] Security surrounding the launch and landing of the space shuttle had been increased because the crew included the first Israeli astronaut.[78] The Merritt Island launch facility, like all sensitive government areas, had increased security after the September 11 attacks.
Purple streak image[edit]
The San Francisco Chronicle reported that an amateur astronomer had taken a five-second exposure that appeared to show "a purplish line near the shuttle" during re-entry.[79] The CAIB report concluded that the image was the result of "camera vibrations during a long-exposure".[80]
Film hoax[edit]
In a hoax inspired by the destruction of Columbia, some images that were purported to be satellite photographs of the shuttle's explosion turned out to be screen captures from the opening scene of the 1998 film Armageddon, where the shuttle Atlantis is destroyed by asteroid fragments. In reality, Columbia disintegrated rather than exploded. In response to the disaster, FX pulled Armageddon from that night's schedule, replacing it with Aliens.[81]
Music[edit]
The 2003 album Bananas by Deep Purple includes "Contact Lost", an instrumental piece written by guitarist Steve Morse in remembrance of the loss. Morse is donating his songwriting royalties to the families of the astronauts.[82]
In Rio de Janeiro and Sao Paulo, Brazil, Brazilians held a Catholic memorial mass for the astronauts of the Space Shuttle Challenger disaster as well as the Columbia tragedy, presided by Father Marcelo Rossi and his partner Belo, where they all sang a Catholic Christian hymn Noites Traicoeiras (Treacherous Nights) in paying tribute to the 14 astronauts who lost their lives aboard the Columbia and Challenger space shuttles.[needs copy edit]
The Hungarian composer Peter Eötvös wrote a piece named Seven for solo violin and orchestra in 2006 in memory of the crew of Columbia. Seven was premiered in 2007 by violinist Akiko Suwanai, conducted by Pierre Boulez, and it was recorded in 2012 with violinist Patricia Kopatchinskaja and the composer conducting.[83]
The 2008 album Columbia: We Dare to Dream by Anne Cabrera was written as a tribute to space shuttle Columbia STS-107, the crew, support teams, recovery teams, and the crew's families.[84] A copy of the album on compact disc was flown aboard space shuttle Discovery mission STS-131 to the International Space Station by astronaut Clayton Anderson in April 2010.[85]
See also[edit]


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Apollo 1
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References[edit]
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 This article incorporates public domain material from websites or documents of the National Aeronautics and Space Administration.
External links[edit]
 Wikimedia Commons has media related to Space Shuttle Columbia disaster.
 Wikisource has original text related to this article:
Columbia Settlement

NASA's Space Shuttle Columbia & Her Crew
NASA STS-107 Crew Memorial web page
Columbia Accident Investigation Board (CAIB)[dead link]
CAIB hearing transcripts[dead link]
Columbia Crew Survival Investigation Report PDF
President Bush's remarks at memorial service – February 4, 2003
Columbia Loss FAQ[dead link] – a discussion of the Columbia disaster
The CBS News Space Reporter's Handbook STS-51L/107 Supplement
How poor presentation skills by engineers may have contributed to the disaster, according to Edward Tufte[dead link]
The 13-min. Crew cabin video (subtitled). Ends 4-min. before the shuttle began to disintegrate.
Video reconstruction of final reentry, raw video, 20 minute video tribute
photos of recovered debris stored on the 16th floor of the Vehicle Assembly Building at KSC


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Space Shuttle Challenger disaster
Challenger explosion.jpg
Space Shuttle Challenger's smoke plume after its in-flight breakup, resulting in its destruction and the deaths of all seven crew members.

Time
11:39:13 EST (16:39:13 UTC)
Date
January 28, 1986
Location
Atlantic Ocean, off the coast of central Florida
Outcome
Grounding of the Space Shuttle fleet for nearly three years during which various safety measures, solid rocket booster redesign, and a new policy on management decision-making for future launches were implemented.
Casualties

Francis R. Scobee, Commander
Michael J. Smith, Pilot
Ronald McNair, Mission Specialist
Ellison Onizuka, Mission Specialist
Judith Resnik, Mission Specialist
Greg Jarvis, Payload Specialist
Christa McAuliffe, Payload Specialist

Inquiries
Rogers Commission



STS-51-L crew: (front row) Michael J. Smith, Dick Scobee, Ronald McNair; (back row) Ellison Onizuka, Christa McAuliffe, Gregory Jarvis, Judith Resnik.
The Space Shuttle Challenger disaster occurred on January 28, 1986, when Space Shuttle Challenger (mission STS-51-L) broke apart 73 seconds into its flight, leading to the deaths of its seven crew members. The spacecraft disintegrated over the Atlantic Ocean, off the coast of Cape Canaveral, Florida at 11:38 EST (16:38 UTC). Disintegration of the vehicle began after an O-ring seal in its right solid rocket booster (SRB) failed at liftoff. The O-ring failure caused a breach in the SRB joint it sealed, allowing pressurized hot gas from within the solid rocket motor to reach the outside and impinge upon the adjacent SRB attachment hardware and external fuel tank. This led to the separation of the right-hand SRB's aft attachment and the structural failure of the external tank. Aerodynamic forces broke up the orbiter.
The crew compartment and many other vehicle fragments were eventually recovered from the ocean floor after a lengthy search and recovery operation. The exact timing of the death of the crew is unknown; several crew members are known to have survived the initial breakup of the spacecraft. The shuttle had no escape system, and the impact of the crew compartment with the ocean surface was too violent to be survivable.
The disaster resulted in a 32-month hiatus in the shuttle program and the formation of the Rogers Commission, a special commission appointed by United States President Ronald Reagan to investigate the accident. The Rogers Commission found NASA's organizational culture and decision-making processes had been key contributing factors to the accident.[1] NASA managers had known contractor Morton Thiokol's design of the SRBs contained a potentially catastrophic flaw in the O-rings since 1977, but failed to address it properly. They also disregarded warnings (an example of "go fever") from engineers about the dangers of launching posed by the low temperatures of that morning and failed to adequately report these technical concerns to their superiors.
What Rogers did not highlight was that the vehicle was never certified to operate in temperatures that low. The O-rings, as well as many other critical components, had no test data to support any expectation of a successful launch in such conditions. Bob Ebeling from Thiokol delivered a biting analysis: "[W]e're only qualified to 40 degrees ...'what business does anyone even have thinking about 18 degrees, we're in no man's land.'"[2]
As a result of the disaster, the Air Force decided to cancel its plans to use the Shuttle for classified military satellite launches from Vandenberg Air Force Base in California, deciding to use the Titan IV instead.
Approximately 17 percent of Americans witnessed the launch live because of the presence of crew member Christa McAuliffe, the first member of the Teacher in Space Project, who would have been the first teacher in space. Media coverage of the accident was extensive: one study reported that 85 percent of Americans surveyed had heard the news within an hour of the accident.[3] The Challenger disaster has been used as a case study in many discussions of engineering safety and workplace ethics.


Contents  [hide]
1 O-ring concerns
2 Pre-launch conditions 2.1 Delays
2.2 Thiokol-NASA conference call
2.3 Ice
3 January 28 launch and failure 3.1 Liftoff and initial ascent
3.2 Plume
3.3 Vehicle breakup
3.4 Post-breakup flight controller dialog
3.5 Cause and time of death
3.6 Prospect of crew escape
4 Aftermath 4.1 Tributes
4.2 Recovery of debris
4.3 Funeral ceremonies
4.4 NASA crisis
5 Investigation 5.1 Rogers Commission
5.2 U.S. House Committee hearings
6 NASA and Air Force response 6.1 Media coverage
6.2 Use as case study
6.3 Continuation of the Shuttle Program
7 Legacy
8 Video documentation
9 Film
10 See also
11 Notes
12 References
13 Further reading
14 External links

O-ring concerns[edit]
Each of the Space Shuttle's two Solid Rocket Boosters (SRBs) was constructed of seven sections, six of which were permanently joined in pairs at the factory. For each flight, the four resulting segments were then assembled in the Vehicle Assembly Building at Kennedy Space Center (KSC), with three field joints. The factory joints were sealed with asbestos-silica insulation applied over the joint, while each field joint was sealed with two rubber O-rings. (After the destruction of Challenger, the number of O-rings per field joint was increased to three.)[4] The seals of all of the SRB joints were required to contain the hot high-pressure gases produced by the burning solid propellant inside, forcing it out of the nozzle at the aft end of each rocket.
During the Space Shuttle design process, a McDonnell Douglas report in September 1971 discussed the safety record of solid rockets. While a safe abort was possible after most types of failures, one was especially dangerous: a burnthrough by hot gases of the rocket's casing. The report stated that "if burnthrough occurs adjacent to [liquid hydrogen/oxygen] tank or orbiter, timely sensing may not be feasible and abort not possible", accurately foreshadowing the Challenger accident.[5] Morton Thiokol was the contractor responsible for the construction and maintenance of the shuttle's SRBs. As originally designed by Thiokol, the O-ring joints in the SRBs were supposed to close more tightly due to forces generated at ignition, but a 1977 test showed that when pressurized water was used to simulate the effects of booster combustion, the metal parts bent away from each other, opening a gap through which gases could leak. This phenomenon, known as "joint rotation," caused a momentary drop in air pressure. This made it possible for combustion gases to erode the O-rings. In the event of widespread erosion, a flame path could develop, causing the joint to burst—which would have destroyed the booster and the shuttle.[6]
Engineers at the Marshall Space Flight Center wrote to the manager of the Solid Rocket Booster project, George Hardy, on several occasions suggesting that Thiokol's field joint design was unacceptable. For example, one engineer suggested that joint rotation would render the secondary O-ring useless, but Hardy did not forward these memos to Thiokol, and the field joints were accepted for flight in 1980.[7]
Evidence of serious O-ring erosion was present as early as the second space shuttle mission, STS-2, which was flown by Columbia. Contrary to NASA regulations, the Marshall Center did not report this problem to senior management at NASA, but opted to keep the problem within their reporting channels with Thiokol. Even after the O-rings were redesignated as "Criticality 1"—meaning that their failure would result in the destruction of the Orbiter—no one at Marshall suggested that the shuttles be grounded until the flaw could be fixed.[7] During the investigation Sally Ride told Dr. Richard Feynman that the O-rings were not tested under 50 °F (10 °C).
By 1985, Marshall and Thiokol realized that they had a potentially catastrophic problem on their hands. They began the process of redesigning the joint with three inches (76 mm) of additional steel around the tang. This tang would grip the inner face of the joint and prevent it from rotating. They did not call for a halt to shuttle flights until the joints could be redesigned, but rather treated the problem as an acceptable flight risk. For example, Lawrence Mulloy, Marshall's manager for the SRB project since 1982, issued and waived launch constraints for six consecutive flights. Thiokol even went as far as to persuade NASA to declare the O-ring problem "closed".[7] Donald Kutyna, a member of the Rogers Commission, later likened this situation to an airline permitting one of its planes to continue to fly despite evidence that one of its wings was about to fall off.
Pre-launch conditions[edit]
Delays[edit]
Challenger was originally set to launch from KSC in Florida at 14:42 Eastern Standard Time (EST) on January 22. Delays in the previous mission, STS-61-C, caused the launch date to be moved to January 23 and then to January 24. Launch was then rescheduled to January 25 due to bad weather at the Transoceanic Abort Landing (TAL) site in Dakar, Senegal. NASA decided to use Casablanca as the TAL site, but because it was not equipped for night landings, the launch had to be moved to the morning (Florida time). Predictions of unacceptable weather at KSC on January 26, caused the launch to be rescheduled for 09:37 EST on January 27.[8]
The launch was delayed the next day, due to problems with the exterior access hatch. First, one of the micro-switch indicators used to verify that the hatch was safely locked malfunctioned.[9] Then, a stripped bolt prevented the closeout crew from removing a closing fixture from the orbiter's hatch.[10] By the time repair personnel had sawed the fixture off, crosswinds at the Shuttle Landing Facility exceeded the limits for a Return to Launch Site (RTLS) abort.[11] While the crew waited for winds to die down, the launch window expired, forcing yet another scrub.
Thiokol-NASA conference call[edit]
Forecasts for January 28 predicted an unusually cold morning, with temperatures close to 31 °F (−1 °C), the minimum temperature permitted for launch. The low temperatures had prompted concerns from Thiokol engineers. At a teleconference on the evening of January 27, Thiokol engineers and managers discussed the weather conditions with NASA managers from Kennedy Space Center and Marshall Space Flight Center. Several engineers (most notably Roger Boisjoly) re-expressed their concerns about the effect of low temperatures on the resilience of the rubber O-rings that sealed the joints of the SRBs, and recommended a launch postponement.[12] They argued that they did not have enough data to determine whether the joints would properly seal if the O-rings were colder than 53 °F (12 °C). This was an important consideration, since the SRB O-rings had been designated as a "Criticality 1" component, meaning that there was no backup if both the primary and secondary O-rings failed, and their failure would destroy the Orbiter and its crew.
Thiokol management initially supported its engineers' recommendation to postpone the launch, but NASA staff opposed a delay. During the conference call, Hardy told Thiokol, "I am appalled. I am appalled by your recommendation." Mulloy said, "My God, Thiokol, when do you want me to launch — next April?"[12] One argument by NASA personnel contesting Thiokol's concerns was that if the primary O-ring failed, the secondary O-ring would still seal. This was unproven, and was in any case an argument that did not apply to a "Criticality 1" component. As astronaut Sally Ride stated when questioning NASA managers before the Rogers Commission, it is forbidden to rely on a backup for a "Criticality 1" component. The backup is there solely to provide redundancy in case of unforeseen failure, not to replace the primary component.
NASA did not know of Thiokol's earlier concerns about the effects of the cold on the O-rings, and did not understand that Rockwell International, the shuttle's prime contractor, viewed the large amount of ice present on the pad as a constraint to launch. Due to NASA's opposition, Thiokol management reversed itself and recommended that the launch proceed as scheduled.[12][13]
Ice[edit]



 Ice on the launch tower hours before Challenger launch
The Thiokol engineers had also argued that the low overnight temperatures (18 °F or −8 °C the evening prior to launch) would almost certainly result in SRB temperatures below their redline of 40 °F (4 °C). Ice had accumulated all over the launch pad, raising concerns that ice could damage the shuttle upon lift-off. The Kennedy Ice Team inadvertently pointed an infrared camera at the aft field joint of the right SRB and found the temperature to be only 8 °F (−13 °C). This was believed to be the result of supercooled air blowing on the joint from the liquid oxygen tank vent. It was much lower than the air temperature and far below the design specifications for the O-rings. However, the 8 °F (−13 °C) reading was later determined to be erroneous, the error caused by not following the temperature probe manufacturer's instructions. Tests and adjusted calculations later confirmed that the temperature of the joint was not substantially different from the ambient temperature.[14]
The temperature on the day of the launch was far lower than had been the case with previous launches: below freezing at 28 to 29 °F (−2.2 to −1.7 °C); previously, the coldest launch had been at 53 °F (12 °C). Although the Ice Team had worked through the night removing ice, engineers at Rockwell still expressed concern. Rockwell engineers watching the pad from their headquarters in Downey, California, were horrified when they saw the amount of ice. They feared that during launch, ice might be shaken loose and strike the shuttle's thermal protection tiles, possibly due to the aspiration induced by the jet of exhaust gas from the SRBs. Rocco Petrone, the head of Rockwell's space transportation division, and his colleagues viewed this situation as a launch constraint, and told Rockwell's managers at the Cape that Rockwell could not support a launch. However, Rockwell's managers at the Cape voiced their concerns in a manner that led Houston-based mission manager Arnold Aldrich to go ahead with the launch. Aldrich decided to postpone the shuttle launch by an hour to give the Ice Team time to perform another inspection. After that last inspection, during which the ice appeared to be melting, Challenger was finally cleared to launch at 11:38 am EST.[13]

January 28 launch and failure[edit]
Further information: STS-51-L Mission timeline
Liftoff and initial ascent[edit]


 This section needs additional citations for verification. Please help improve this article by adding citations to reliable sources. Unsourced material may be challenged and removed. (January 2011)



 Gray smoke escaping from the right side SRB
The following account of the accident is derived from real time telemetry data and photographic analysis, as well as from transcripts of air-to-ground and mission control voice communications.[15] All times are given in seconds after launch and correspond to the telemetry time-codes from the closest instrumented event to each described event.[16]
Until liftoff actually occurs, the Space Shuttle main engines (SSMEs) can be safely shut down and the launch aborted if necessary. At liftoff time (T=0, which was at 11:38:00.010 EST), the three SSMEs were at 100% of their original rated performance, and began throttling up to 104% under computer control. At this moment, the two SRBs were ignited and hold-down bolts were released with explosives, freeing the vehicle from the pad. With the first vertical motion of the vehicle, the gaseous hydrogen vent arm retracted from the External Tank (ET) but failed to latch back. Review of film shot by pad cameras showed that the arm did not re-contact the vehicle, and thus it was ruled out as a contributing factor in the accident.[16] The post-launch inspection of the pad also revealed that kick springs on four of the hold-down bolts were missing, but they were similarly ruled out as a possible cause.[17]


File:Challenger Launch and Breakup.ogv
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Challenger launch and breakup
Later review of launch film showed that at T+0.678, strong puffs of dark gray smoke were emitted from the right-hand SRB near the aft strut that attaches the booster to the ET. The last smoke puff occurred at about T+2.733. The last view of smoke around the strut was at T+3.375. It was later determined that these smoke puffs were caused by the opening and closing of the aft field joint of the right-hand SRB. The booster's casing had ballooned under the stress of ignition. As a result of this ballooning, the metal parts of the casing bent away from each other, opening a gap through which hot gases—above 5,000 °F (2,760 °C)—leaked. This had occurred in previous launches, but each time the primary O-ring had shifted out of its groove and formed a seal. Although the SRB was not designed to function this way, it appeared to work well enough, and Morton-Thiokol changed the design specs to accommodate this process, known as extrusion.
While extrusion was taking place, hot gases leaked past (a process called "blow-by"), damaging the O-rings until a seal was made. Investigations by Morton-Thiokol engineers determined that the amount of damage to the O-rings was directly related to the time it took for extrusion to occur, and that cold weather, by causing the O-rings to harden, lengthened the time of extrusion. (The redesigned SRB field joint used subsequent to the Challenger accident used an additional interlocking mortise and tang with a third O-ring, mitigating blow-by.)
On the morning of the disaster, the primary O-ring had become so hard due to the cold that it could not seal in time. The secondary O-ring was not in its seated position due to the metal bending. There was now no barrier to the gases, and both O-rings were vaporized across 70 degrees of arc. However, aluminum oxides from the burned solid propellant sealed the damaged joint, temporarily replacing the O-ring seal before actual flame rushed through the joint.
As the vehicle cleared the tower, the SSMEs were operating at 104% of their rated maximum thrust, and control switched from the Launch Control Center (LCC) at Kennedy to the Mission Control Center (MCC) at Johnson Space Center in Houston, Texas. To prevent aerodynamic forces from structurally overloading the orbiter, at T+28 the SSMEs began throttling down to limit the velocity of the shuttle in the dense lower atmosphere, as per normal operating procedure. At T+35.379, the SSMEs throttled back further to the planned 65%. Five seconds later, at about 5,800 metres (19,000 ft), Challenger passed through Mach 1. At T+51.860, the SSMEs began throttling back up to 104% as the vehicle passed beyond Max Q, the period of maximum aerodynamic pressure on the vehicle.
Plume[edit]



 Plume on right SRB at T+ 58.778 seconds
Beginning at about T+37 and for 27 seconds, the shuttle experienced a series of wind shear events that were stronger than on any previous flight.[18]
At T+58.788, a tracking film camera captured the beginnings of a plume near the aft attach strut on the right SRB. Unknown to those on Challenger or in Houston, hot gas had begun to leak through a growing hole in one of the right-hand SRBs joints. The force of the wind shear shattered the temporary oxide seal that had taken the place of the damaged O-rings, removing the last barrier to flame rushing through the joint. Had it not been for the wind shear, the fortuitous oxide seal might have held through booster burnout.
Within a second, the plume became well defined and intense. Internal pressure in the right SRB began to drop because of the rapidly enlarging hole in the failed joint, and at T+60.238 there was visual evidence of flame burning through the joint and impinging on the external tank.[15]
At T+64.660, the plume suddenly changed shape, indicating that a leak had begun in the liquid hydrogen tank, located in the aft portion of the external tank. The nozzles of the main engines pivoted under computer control to compensate for the unbalanced thrust produced by the booster burn-through. The pressure in the shuttle's external liquid hydrogen tank began to drop at T+66.764, indicating the effect of the leak.[15]
At this stage the situation still seemed normal both to the astronauts and to flight controllers. At T+68, the CAPCOM Richard O. Covey informed the crew that they were "go at throttle up", and Commander Dick Scobee confirmed the call. His response, "Roger, go at throttle up," was the last communication from Challenger on the air-to-ground loop.
Vehicle breakup[edit]


File:Challenger - STS-51-L Explosion.ogg
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 Challenger breakup (346 kB, ogg/Theora format)


Challenger begins to disintegrate.
At T+72.284, the right SRB pulled away from the aft strut attaching it to the external tank. Later analysis of telemetry data showed a sudden lateral acceleration to the right at T+72.525, which may have been felt by the crew. The last statement captured by the crew cabin recorder came just half a second after this acceleration, when Pilot Michael J. Smith said "Uh oh."[19] Smith may also have been responding to onboard indications of main engine performance, or to falling pressures in the external fuel tank.
At T+73.124, the aft dome of the liquid hydrogen tank failed, producing a propulsive force that pushed the hydrogen tank into the liquid oxygen tank in the forward part of the ET. At the same time, the right SRB rotated about the forward attach strut, and struck the intertank structure. This resulted in the spontaneous conflagration of the fuel which exploded the external tank, creating a massive plume of water vapor exhaust that enveloped the entire stack.
The breakup of the vehicle began at T+73.162 seconds and at an altitude of 48,000 feet (15 km).[20] With the external tank disintegrating (and with the semi-detached right SRB contributing its thrust on an anomalous vector), Challenger veered from its correct attitude with respect to the local airflow, resulting in a load factor of up to 20 (or 20 g), well over its design limit of 5 g and was quickly torn apart by abnormal aerodynamic forces (the orbiter itself did not explode). The two SRBs, which could withstand greater aerodynamic loads, separated from the ET and continued in uncontrolled powered flight. The SRB casings were made of half-inch (12.7 mm) thick steel and were much stronger than the orbiter and ET; thus, both SRBs survived the breakup of the space shuttle stack, even though the right SRB was still suffering the effects of the joint burn-through that had set the destruction of Challenger in motion.[17]
The more robustly constructed crew cabin also survived the breakup of the launch vehicle; while the SRBs were subsequently destroyed remotely by the Range Safety Officer, the detached cabin continued along a ballistic trajectory and was observed exiting the cloud of gases at T+75.237.[17] Twenty-five seconds after the breakup of the vehicle, the altitude of the crew compartment peaked at a height of 65,000 feet (20 km).[20]
The Thiokol engineers who had opposed the decision to launch were watching the events on television. They had believed that any O-ring failure would have occurred at liftoff, and thus were happy to see the shuttle successfully leave the launch pad. At about one minute after liftoff, a friend of Boisjoly said to him "Oh God. We made it. We made it!" Boisjoly recalled that when the shuttle exploded a few seconds later, "we all knew exactly what happened."[12]
Post-breakup flight controller dialog[edit]



Jay Greene at his console after the breakup of Challenger

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 Mission Control during the liftoff of Challenger (STS-51-L)
In Mission Control, there was a burst of static on the air-to-ground loop as Challenger disintegrated. Television screens showed a cloud of smoke and water vapor (the product of hydrogen combustion) where Challenger had been, with pieces of debris falling toward the ocean. At about T+89, flight director Jay Greene prompted his flight dynamics officer (FIDO) for information. FIDO responded that "...the (radar) filter has discreting sources", a further indication that Challenger had broken into multiple pieces. A minute later, the ground controller reported "negative contact (and) loss of downlink" of radio and telemetry data from Challenger. Greene ordered his team to "watch your data carefully" and look for any sign that the Orbiter had escaped.
At T+110.250, the Range Safety Officer (RSO) at the Cape Canaveral Air Force Station sent radio signals that activated the range safety system's "destruct" packages on board both solid rocket boosters. This was a normal contingency procedure, undertaken because the RSO judged the free-flying SRBs a possible threat to land or sea. The same destruct signal would have destroyed the External Tank had it not already disintegrated.[21]
Public affairs officer Steve Nesbitt reported: "Flight controllers here looking very carefully at the situation. Obviously a major malfunction. We have no downlink."[15]
On the Mission Control loop, Greene ordered that contingency procedures be put into effect; these procedures included locking the doors of the control center, shutting down telephone communications with the outside world, and following checklists that ensured that the relevant data were correctly recorded and preserved.[citation needed]
Nesbitt relayed this information to the public: "We have a report from the Flight Dynamics Officer that the vehicle has exploded. The flight director confirms that. We are looking at checking with recovery forces to see what can be done at this point."[15]
Cause and time of death[edit]





The intact crew cabin was seen exiting the cloud by a tracking camera after its trajectory carried it across an adjacent contrail.



Enlarged detail of the previous picture, the arrow indicating the crew cabin. The nose cone containing the RCS thrusters is missing.



Astronauts from a later Shuttle flight (STS-34) stand next to their PEAPs
The crew cabin, made of reinforced aluminum, was a particularly robust section of the shuttle.[22] During vehicle breakup, it detached in one piece and slowly tumbled into a ballistic arc. NASA estimated the load factor at separation to be between 12 and 20 g; within two seconds it had already dropped to below 4 g and within ten seconds the cabin was in free fall. The forces involved at this stage were likely insufficient to cause major injury.
At least some of the astronauts were likely alive and at least briefly conscious after the breakup, as three of the four recovered Personal Egress Air Packs (PEAPs) on the flight deck were found to have been activated. Investigators found their remaining unused air supply roughly consistent with the expected consumption during the 2 minute 45 second post-breakup trajectory.
While analyzing the wreckage, investigators discovered that several electrical system switches on Pilot Mike Smith's right-hand panel had been moved from their usual launch positions. Fellow Astronaut Richard Mullane wrote, "These switches were protected with lever locks that required them to be pulled outward against a spring force before they could be moved to a new position." Later tests established that neither force of the explosion nor the impact with the ocean could have moved them, indicating that Smith made the switch changes, presumably in a futile attempt to restore electrical power to the cockpit after the crew cabin detached from the rest of the orbiter.[23]
Whether the astronauts remained conscious long after the breakup is unknown, and largely depends on whether the detached crew cabin maintained pressure integrity. If it did not, the time of useful consciousness at that altitude is just a few seconds; the PEAPs supplied only unpressurized air, and hence would not have helped the crew to retain consciousness. If, on the other hand, the cabin was not depressurized or only slowly depressurizing, the astronauts may have been conscious for the entire fall until impact.
NASA routinely trained shuttle astronauts for splashdown events, but the cabin hit the ocean surface at roughly 207 mph (333 km/h), with an estimated deceleration at impact of well over 200 g, far beyond the structural limits of the crew compartment or crew survivability levels.[20]
On July 28, 1986, Rear Admiral Richard H. Truly, NASA's Associate Administrator for Space Flight and a former astronaut, released a report from Joseph P. Kerwin, biomedical specialist from the Johnson Space Center in Houston, relating to the deaths of the astronauts in the accident. Kerwin, a veteran of the Skylab 2 mission, had been commissioned to undertake the study soon after the accident. According to the Kerwin Report:

The findings are inconclusive. The impact of the crew compartment with the ocean surface was so violent that evidence of damage occurring in the seconds which followed the disintegration was masked. Our final conclusions are:
the cause of death of the Challenger astronauts cannot be positively determined;
the forces to which the crew were exposed during Orbiter breakup were probably not sufficient to cause death or serious injury; and
the crew possibly, but not certainly, lost consciousness in the seconds following Orbiter breakup due to in-flight loss of crew module pressure.[20]
Some experts believe most if not all of the crew were alive and possibly conscious during the entire descent until impact with the ocean. Astronaut and NASA lead accident investigator Robert Overmyer said "Scob fought for any and every edge to survive. He flew that ship without wings all the way down... they were alive."[22]
Prospect of crew escape[edit]
Further information: Shuttle ejection escape systems, Post-Challenger abort enhancements
During powered flight of the space shuttle, crew escape was not possible. Launch escape systems were considered several times during shuttle development, but NASA's conclusion was that the shuttle's expected high reliability would preclude the need for one. Modified SR-71 Blackbird ejection seats and full pressure suits were used on the first four shuttle orbital missions, which were considered test flights, but they were removed for the "operational" missions that followed. (The Columbia Accident Investigation Board later declared, after the 2003 Columbia re-entry disaster, that the space shuttle system should never have been declared operational because it is experimental by nature due to the limited number of flights as compared to certified commercial aircraft.) Providing a launch escape system for larger crews was considered undesirable due to "limited utility, technical complexity and excessive cost in dollars, weight or schedule delays."[21]
After the loss of Challenger, the question was re-opened, and NASA considered several different options, including ejector seats, tractor rockets and bailing out through the bottom of the orbiter. However, NASA once again concluded that all of the launch escape systems considered would be impractical due to the sweeping vehicle modifications that would have been necessary and the resultant limitations on crew size. A system was designed to give the crew the option to leave the shuttle during gliding flight; however, this system would not have been usable in the Challenger situation.[24]
Aftermath[edit]
 Wikisource has original text related to this article:
Ronald Reagan Announces the Challenger Disaster



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U.S. President Ronald Reagan addresses the nation after the shuttle disaster.
Tributes[edit]
On the night of the disaster, President Ronald Reagan had been scheduled to give his annual State of the Union address. He initially announced that the address would go on as scheduled, but then postponed the State of the Union address for a week and instead gave a national address on the Challenger disaster from the Oval Office of the White House. It was written by Peggy Noonan, and was listed as one of the most significant speeches of the 20th century in a survey of 137 communication scholars.[25][26] It finished with the following statement, which quoted from the poem "High Flight" by John Gillespie Magee, Jr.:

We will never forget them, nor the last time we saw them, this morning, as they prepared for their journey and waved goodbye and 'slipped the surly bonds of Earth' to 'touch the face of God.'[27]



 Memorial service on January 31, 1986, at Houston, Texas, attended by Ronald Reagan and First Lady Nancy Reagan (left).
Three days later, Reagan and his wife Nancy traveled to the Johnson Space Center to speak at a memorial service honoring the astronauts where he stated:

Sometimes, when we reach for the stars, we fall short. But we must pick ourselves up again and press on despite the pain.[28]
It was attended by 6,000 NASA employees and 4,000 guests,[29][30] as well as by the families of the crew.[31] During the ceremony, an Air Force band led the singing of "God Bless America" as NASA T-38 Talon jets flew directly over the scene, in the traditional missing-man formation.[29][30] All activities were broadcast live by the national television networks.[29]
President Reagan would further mention the Challenger astronauts at the beginning of his State of the Union address on February 4.
Recovery of debris[edit]



 Recovered right solid rocket booster showing the hole caused by the plume.
In the first minutes after the accident, recovery efforts were begun by NASA's Launch Recovery Director, who ordered the ships normally used by NASA for recovery of the solid rocket boosters to be sent to the location of the water impact. Search and rescue aircraft were also dispatched. At this stage, however, debris was still falling, and the Range Safety Officer (RSO) held both aircraft and ships out of the impact area until it was considered safe for them to enter. It was about an hour until the RSO allowed the recovery forces to begin their work.[32]
The search and rescue operations that took place in the first week after the Challenger accident were managed by the Department of Defense on behalf of NASA, with assistance from the United States Coast Guard, and mostly involved surface searches. According to the Coast Guard, "the operation was the largest surface search in which they had participated."[32] This phase of operations lasted until February 7. Thereafter, recovery efforts were managed by a Search, Recovery, and Reconstruction team; its aim was to salvage debris that would help in determining the cause of the accident. Sonar, divers, remotely operated submersibles and manned submersibles were all used during the search, which covered an area of 480 nautical miles (890 km), and took place at depths of up to 370 meters (1,210 ft). On March 7, divers from the USS Preserver identified what might be the crew compartment on the ocean floor.[33][34] The finding, along with discovery of the remains of all seven crew members, was confirmed the next day and on March 9, NASA announced the finding to the press.[35] While recovering the remains of the crew, Gregory Jarvis's body floated out of the shattered crew compartment and was lost to the diving team. A day later, his body was seen floating on the ocean's surface. It sank as a team prepared to pull him from the water. His body was recovered on a later dive. His body had settled 101.2 feet below the water on the surface of the ocean, some 0.7 nautical miles from the final resting place of the crew compartment. He was recovered and brought to the surface before being processed with the other astronauts and then prepared for release to his family.
The crew transfer took place on April 29, 1986, three months and one day after the accident. Seven hearses carried the astronauts remains from the Life Sciences Facility on Cape Canaveral, to a waiting MAC C-141 aircraft. Their caskets were each draped with an American flag and carried past an honor guard and followed by an astronaut escort. The astronaut escorts for the Challenger crew were: Dan Brandenstein, Jim Buckley, Norm Thagard, Charles Bolden, Tammy Jernigan, Dick Richards, and Loren Shriver. Once the astronauts' remains were aboard the jet, they were flown to Dover Air Force Base in Delaware to be processed and then released to their loved ones.
By May 1, enough of the right solid rocket booster had been recovered to determine the original cause of the accident, and the major salvage operations were concluded. While some shallow-water recovery efforts continued, this was unconnected with the accident investigation; it aimed to recover debris for use in NASA's studies of the properties of materials used in spacecraft and launch vehicles.[32] The recovery operation was able to pull 15 short tons (14 t) of debris from the ocean; 55% of Challenger, 5% of the crew cabin and 65% of the satellite cargo is still missing.[36] Some of the missing debris continued to wash up on Florida shores for some years, such as on December 17, 1996, nearly 11 years after the incident, when two large pieces of the shuttle were found at Cocoa Beach.[37] Under 18 U.S.C. § 641 it is against the law to be in possession of Challenger debris, and any newly discovered pieces must be turned in to NASA.[38]
On board Challenger was an American flag, dubbed the Challenger flag, that was sponsored by Boy Scout Troop 514 of Monument, Colorado. It was recovered intact, still sealed in its plastic container.[39]
All recovered non-organic debris from Challenger was ultimately buried in a former missile silo at Cape Canaveral Air Force Station Launch Complex 31.
Funeral ceremonies[edit]



 The remains of the Challenger crew are transferred to a C-141 at the NASA KSC Shuttle Landing Facility, bound for Dover Air Force Base, Delaware.
The remains of the crew that were identifiable were returned to their families on April 29, 1986. Three of the crew members, Judith Resnik, Dick Scobee, and Capt. Michael J. Smith, were buried by their families at Arlington National Cemetery at individual grave sites. Mission Specialist Lt Col Ellison Onizuka was buried at the National Memorial Cemetery of the Pacific in Honolulu, Hawaii. Unidentified crew remains were buried communally at the Space Shuttle Challenger Memorial in Arlington on May 20, 1986.[40]
NASA crisis[edit]








The launch attempt of the Delta 3914 carrying the GOES-G, ends in failure 71 seconds later, May 3, 1986
Several National Reconnaissance Office (NRO) satellites that only the shuttle could launch were grounded because of the accident, a dilemma NRO had feared since the 1970s when the shuttle was designated as the United States' primary launch system for all government and commercial payloads.[41][42] NASA had difficulties with its own Titan rocket and Delta rocket programs, due to other unexpected rocket failures occurring before and after the Challenger disaster. On August 28, 1985, a Titan 34D[43] carrying a KH-11 KENNAN satellite exploded after liftoff over Vandenberg Air Force Base, when the first stage propellant motor failed. It was the first failure of a Titan missile since 1978. On April 18, 1986, another Titan 34D-9[44][45] carrying a classified payload,[45] said to be a Big Bird spy satellite, exploded at about 830 feet above the pad after liftoff over Vandenberg AFB, when a burnthrough occurred on one of the rocket boosters. On May 3, 1986, a Delta 3914[43] carrying the GOES-G weather satellite[46] exploded 71 seconds after liftoff over Cape Canaveral Air Force Station due to an electrical malfunction on the Delta's first stage, which prompted the range safety officer on the ground to decide to destroy the rocket, just as a few of the rocket's boosters were jettisoned. As a result of these three failures, NASA decided to cancel all Titan and Delta launches from Cape Canaveral and Vandenberg for four months, until the problem in the rockets' designs were solved.
Due to the shuttle fleet being grounded, excess ammonium perchlorate that was manufactured as rocket fuel was kept on site at the Pacific Engineering and Production Company of Nevada (PEPCON) plant in Henderson, Nevada. This excess ammonium perchlorate later caught fire and the resulting explosion destroyed the PEPCON facility and the neighboring Kidd & Co marshmallow factory.[47]
Investigation[edit]
In the aftermath of the accident, NASA was criticized for its lack of openness with the press. The New York Times noted on the day after the accident that "neither Jay Greene, flight director for the ascent, nor any other person in the control room, was made available to the press by the space agency".[48] In the absence of reliable sources, the press turned to speculation; both The New York Times and United Press International ran stories suggesting that a fault with the space shuttle external tank had caused the accident, despite the fact that NASA's internal investigation had quickly focused in on the solid rocket boosters.[49][50] "The space agency," wrote space reporter William Harwood, "stuck to its policy of strict secrecy about the details of the investigation, an uncharacteristic stance for an agency that long prided itself on openness."[49]
Rogers Commission[edit]
Main article: Rogers Commission Report



 Simplified cross section of the joints between rocket segments SRB. Legend:
 A - steel wall thickness 12.7 mm,
 B - base O-ring gasket,
 C - backup O-ring gasket,
 D - Strengthening-Cover band,
 E - insulation,
 F - insulation,
 G - carpeting,
 H - sealing paste,
 I - fixed propellant
The Presidential Commission on the Space Shuttle Challenger Accident, also known as the Rogers Commission (after its chairman), was formed to investigate the disaster. The commission members were Chairman William P. Rogers, Vice Chairman Neil Armstrong, David Acheson, Eugene Covert, Richard Feynman, Robert Hotz, Donald Kutyna, Sally Ride, Robert Rummel, Joseph Sutter, Arthur Walker, Albert Wheelon, and Chuck Yeager. The commission worked for several months and published a report of its findings. It found that the Challenger accident was caused by a failure in the O-rings sealing a joint on the right solid rocket booster, which allowed pressurized hot gases and eventually flame to "blow by" the O-ring and make contact with the adjacent external tank, causing structural failure. The failure of the O-rings was attributed to a faulty design, whose performance could be too easily compromised by factors including the low temperature on the day of launch.[51]



 Members of the Rogers Commission arrive at Kennedy Space Center.
More broadly, the report also considered the contributing causes of the accident. Most salient was the failure of both NASA and Morton Thiokol to respond adequately to the danger posed by the deficient joint design. Rather than redesigning the joint, they came to define the problem as an acceptable flight risk. The report found that managers at Marshall had known about the flawed design since 1977, but never discussed the problem outside their reporting channels with Thiokol—a flagrant violation of NASA regulations. Even when it became more apparent how serious the flaw was, no one at Marshall considered grounding the shuttles until a fix could be implemented. On the contrary, Marshall managers went as far as to issue and waive six launch constraints related to the O-rings.[7] The report also strongly criticized the decision-making process that led to the launch of Challenger, saying that it was seriously flawed.[13]

...failures in communication... resulted in a decision to launch 51-L based on incomplete and sometimes misleading information, a conflict between engineering data and management judgments, and a NASA management structure that permitted internal flight safety problems to bypass key Shuttle managers.
—Richard Feynman, [13]
One of the commission's best-known members was theoretical physicist Richard Feynman. During a televised hearing, he famously demonstrated how the O-rings became less resilient and subject to seal failures at ice-cold temperatures by immersing a sample of the material in a glass of ice water. He was so critical of flaws in NASA's "safety culture" that he threatened to remove his name from the report unless it included his personal observations on the reliability of the shuttle, which appeared as Appendix F.[52] In the appendix, he argued that the estimates of reliability offered by NASA management were wildly unrealistic, differing as much as a thousandfold from the estimates of working engineers. "For a successful technology," he concluded, "reality must take precedence over public relations, for nature cannot be fooled."[53]
Richard Feynman wrote that while other members of the Commission met with NASA and supplier top management he sought out the engineers and technicians. That is how he became aware of the O-ring problem. He also noted that one of the Commission's main worries concerned the type of leather binding in which to present the report to the President.[14]
U.S. House Committee hearings[edit]
The U.S. House Committee on Science and Technology also conducted hearings, and on October 29, 1986, released its own report on the Challenger accident.[54] The committee reviewed the findings of the Rogers Commission as part of its investigation, and agreed with the Rogers Commission as to the technical causes of the accident. However, it differed from the committee in its assessment of the accident's contributing causes:

...the Committee feels that the underlying problem which led to the Challenger accident was not poor communication or underlying procedures as implied by the Rogers Commission conclusion. Rather, the fundamental problem was poor technical decision-making over a period of several years by top NASA and contractor personnel, who failed to act decisively to solve the increasingly serious anomalies in the Solid Rocket Booster joints.[54]
NASA and Air Force response[edit]



 Astronaut Charles F. Bolden reads a passage from the Bible during memorial services for the seven crew members of 51-L who lost their lives aboard the Space Shuttle Challenger in a Florida accident (NASA)
After the Challenger accident, further shuttle flights were suspended, pending the results of the Rogers Commission investigation. Whereas NASA had held an internal inquiry into the Apollo 1 fire in 1967, its actions after Challenger were more constrained by the judgment of outside bodies. The Rogers Commission offered nine recommendations on improving safety in the space shuttle program, and NASA was directed by President Reagan to report back within thirty days as to how it planned to implement those recommendations.[55]
When the disaster occurred, the Air Force had performed extensive modifications of its Space Launch Complex 6 (SLC-6, pronounced as "Slick Six") at Vandenberg Air Force Base in California, for launch and landing operations of classified Shuttle launches of satellites in polar orbit, and was planning its first polar flight for October 15, 1986. Originally built for the Manned Orbital Laboratory project cancelled in 1969, the modifications were proving problematic and expensive,[56] costing over $4 billion. The Challenger loss motivated the Air Force to set in motion a chain of events that finally led to the May 13, 1988 decision to cancel its Vandenberg Shuttle launch plans, in favor of the Titan IV unmanned launch vehicle.
In response to the commission's recommendation, NASA initiated a total redesign of the space shuttle's solid rocket boosters, which was watched over by an independent oversight group as stipulated by the commission.[55] NASA's contract with Morton Thiokol, the contractor responsible for the solid rocket boosters, included a clause stating that in the event of a failure leading to "loss of life or mission," Thiokol would forfeit $10 million of its incentive fee and formally accept legal liability for the failure. After the Challenger accident, Thiokol agreed to "voluntarily accept" the monetary penalty in exchange for not being forced to accept liability.[57]
NASA also created a new Office of Safety, Reliability and Quality Assurance, headed as the commission had specified by a NASA associate administrator who reported directly to the NASA administrator. George Martin, formerly of Martin Marietta, was appointed to this position.[58] Former Challenger flight director Jay Greene became chief of the Safety Division of the directorate.[59]
The unrealistically optimistic launch schedule pursued by NASA had been criticized by the Rogers Commission as a possible contributing cause to the accident. After the accident, NASA attempted to aim at a more realistic shuttle flight rate: it added another orbiter, Endeavour, to the space shuttle fleet to replace Challenger, and it worked with the Department of Defense to put more satellites in orbit using expendable launch vehicles rather than the shuttle.[60] In August 1986, President Reagan also announced that the shuttle would no longer carry commercial satellite payloads. After a 32-month hiatus, the next shuttle mission, STS-26, was launched on September 29, 1988.
Although changes were made by NASA after the Challenger accident, many commentators have argued that the changes in its management structure and organizational culture were neither deep nor long-lasting.
After the Space Shuttle Columbia disaster in 2003, attention once again focused on the attitude of NASA management towards safety issues. The Columbia Accident Investigation Board (CAIB) concluded that NASA had failed to learn many of the lessons of Challenger. In particular, the agency had not set up a truly independent office for safety oversight; the CAIB felt that in this area, "NASA's response to the Rogers Commission did not meet the Commission's intent".[61] The CAIB believed that "the causes of the institutional failure responsible for Challenger have not been fixed," saying that the same "flawed decision making process" that had resulted in the Challenger accident was responsible for Columbia's destruction seventeen years later.[62]
Media coverage[edit]
While the presence of New Hampshire schoolteacher Christa McAuliffe on the Challenger crew had provoked some media interest, there was little live broadcast coverage of the launch. The only live national TV coverage available publicly was provided by CNN; although several radio networks were also live. Due to McAuliffe's presence on the mission, NASA arranged for many U.S. public schools to view the launch live on NASA TV.[63] As a result, many who were schoolchildren in the US in 1986 did in fact have the opportunity to view the launch live. After the accident, however, 17% of respondents in one study reported that they had seen the shuttle launch, while 85% said that they had learned of the accident within an hour. As the authors of the paper reported, "only two studies have revealed more rapid dissemination [of news]." (One of those studies was of the spread of news in Dallas after President John F. Kennedy's assassination, while the other was the spread of news among students at Kent State regarding President Franklin D. Roosevelt's death.)[64] Another study noted that "even those who were not watching television at the time of the disaster were almost certain to see the graphic pictures of the accident replayed as the television networks reported the story almost continuously for the rest of the day."[65] Children were even more likely than adults to have seen the accident live, since many children — 48 percent of nine to thirteen-year-olds, according to a New York Times poll — watched the launch at school.[65]
Following the day of the accident, press interest remained high. While only 535 reporters were accredited to cover the launch, three days later there were 1467 reporters at Kennedy Space Center and another 1040 at Johnson Space Center. The event made headlines in newspapers worldwide.[49]
Use as case study[edit]
The Challenger accident has frequently been used as a case study in the study of subjects such as engineering safety, the ethics of whistle-blowing, communications, group decision-making, and the dangers of groupthink. It is part of the required readings for engineers seeking a professional license in Canada and other countries.[66] Roger Boisjoly, the engineer who had warned about the effect of cold weather on the O-rings, left his job at Morton Thiokol and became a speaker on workplace ethics.[67] He argues that the caucus called by Morton Thiokol managers, which resulted in a recommendation to launch, "constituted the unethical decision-making forum resulting from intense customer intimidation."[68] For his honesty and integrity leading up to and directly following the shuttle disaster, Roger Boisjoly was awarded the Prize for Scientific Freedom and Responsibility from the American Association for the Advancement of Science. Many colleges and universities have also used the accident in classes on the ethics of engineering.[69][70]
Information designer Edward Tufte has claimed that the Challenger accident is an example of the problems that can occur from the lack of clarity in the presentation of information. He argues that if Morton Thiokol engineers had more clearly presented the data that they had on the relationship between low temperatures and burn-through in the solid rocket booster joints, they might have succeeded in persuading NASA managers to cancel the launch. To demonstrate this, he took all of the data he claimed the engineers had presented during the briefing, and reformatted it onto a single graph of O-ring damage versus external launch temperature, showing the effects of cold on the degree of O-ring damage. Tufte then placed the proposed launch of Challenger on the graph according to its predicted temperature at launch. According to Tufte, the launch temperature of Challenger was so far beyond from the coldest launch with the worst damage ever seen to date, that even a casual observer could have determined that the risk of disaster was severe.[71]
Tufte has also argued that poor presentation of information may have also affected NASA decisions during the last flight of the space shuttle Columbia.[72]
However, Robison, a Rochester Institute of Technology professor, and Boisjoly vigorously repudiated Tufte's conclusions about the Morton Thiokol engineers' role in the loss of Challenger. First they say that the engineers didn't have the information available as Tufte claimed: "But they did not know the temperatures even though they did try to obtain that information. Tufte has not gotten the facts right even though the information was available to him had he looked for it." They further argue that Tufte "misunderstands thoroughly the argument and evidence the engineers gave". They also criticized Tufte's diagram as "fatally flawed by Tufte's own criteria. The vertical axis tracks the wrong effect, and the horizontal axis cites temperatures not available to the engineers and, in addition, mixes O-ring temperatures and ambient air temperature as though the two were the same."[73]
Continuation of the Shuttle Program[edit]
After the accident, NASA's Space Shuttle fleet was grounded for almost three years while the investigation, hearings, engineering redesign of the SRBs, and other behind-the-scenes technical and management reviews, changes, and preparations were taking place. At 11:37 on September 29, 1988, Space Shuttle Discovery lifted off with a crew of five[74] from Kennedy Space Center pad 39-B. It carried a Tracking and Data Relay Satellite, TDRS-C (named TDRS-3 after deployment), which replaced TDRS-B, the satellite that was launched and lost on Challenger. The "Return to Flight" launch of Discovery also represented a test of the redesigned boosters, a shift to a more conservative stance on safety (e.g., it was the first time the crew had launched in pressure suits since STS-4, the last of the four initial Shuttle test flights), and a chance to restore national pride in the American space program, especially manned space flight. The mission, STS-26, was a success (with only two minor system failures, one of a cabin cooling system and one of a Ku-band antenna), and a regular schedule of STS flights followed, continuing without extended interruption until the 2003 Columbia disaster.
Barbara Morgan, the backup astronaut for McAuliffe who trained with her in the Teacher in Space program and was at KSC watching her launch on January 28, 1986, flew on STS-118 as a Mission Specialist in August 2007.
Legacy[edit]



 The Space Shuttle Challenger Memorial in Arlington National Cemetery, where some remains were buried
The families of the Challenger crew organized the Challenger Center for Space Science Education as a permanent memorial to the crew. Fifty-two learning centers have been established by this non-profit organization.[citation needed]
Rendez-vous Houston is remembered[by whom?] for being the concert which celebrated the astronauts of the Challenger disaster, which had happened only two and a half months beforehand. It was a live performance by musician Jean Michel Jarre in Houston on the evening of April 5, 1986. Jarre and crew member Ron McNair were friends. McNair was supposed to play the saxophone from space during the track "Last Rendez-Vous". It was to have become the first musical piece played and recorded in space.[citation needed] His substitute for the concert was Houston native Kirk Whalum.[citation needed]



 Squadron "Challenger" 17 logo
The Squadron "Challenger" 17 is an Air Force unit in the Texas A&M Corps of Cadets that emphasizes athletic and academic success in honor of the Challenger crew.[75] The unit was established in 1992.[76]
In Huntsville, Alabama, home of Marshall Space Flight Center, Challenger Elementary School, Challenger Middle School, and the future McNair Junior High School are all named in memory of the crew. (Huntsville has also named new schools posthumously in memory of each of the Apollo I astronauts and Space Shuttle Columbia.) Streets in a neighborhood established in the late-1980s in nearby Decatur are named in memory of each of the Challenger astronauts (Onizuka excluded), as well as the three deceased Apollo I astronauts. Julian Harris Elementary School is located on McAuliffe Drive, and its mascot is the Challengers.
An elementary school in Nogales, Arizona, commemorates the accident in name, Challenger Elementary School, and their school motto, "Reach for the sky". The suburbs of Seattle, Washington are home to Challenger Elementary School in Issaquah, Washington[77] and Christa McAuliffe Elementary School in Sammamish, Washington.[78] In San Diego, California, the next-opened public middle school in the San Diego Unified School District was named Challenger Middle School.[79] The City of Palmdale, the birthplace of the entire shuttle fleet, and its neighbor City of Lancaster, California, both renamed 10th Street East, from Avenue M to Edwards Air Force Base, to Challenger Way in honor of the lost shuttle and its crew.[citation needed] This was the road that the Challenger, Enterprise, and Columbia all were towed along in their initial move from U.S. Air Force Plant 42 to Edwards AFB after completion since Palmdale airport had not yet installed the shuttle crane for placement of an orbiter on the 747 Shuttle Carrier Aircraft.[citation needed] In addition, the City of Lancaster has built Challenger Middle School, and Challenger Memorial Hall at the former site of the Antelope Valley Fairgrounds, all in tribute to the Challenger shuttle and crew.[citation needed] Another school was opened in Chicago, IL as the Sharon Christa McAuliffe Elementary school.[80] The public Peers Park in Palo Alto, California features a "Challenger Memorial Grove" that includes redwood trees grown from seeds carried aboard Challenger in 1985.[81] In 1986 in Webster, Texas,the "Challenger Seven Memorial Park" was also dedicated in remembrance of the event.[82]
In Cocoa, Brevard County, Florida (the county where Cape Canaveral and KSC are located), Challenger 7 Elementary School is named in memory of the seven astronauts who lost their lives.[83] There is also a middle school in neighboring Rockledge, McNair Magnet School, named after astronaut Ronald McNair.[84] A middle school (formerly high school) in Mohawk, New York is named after payload specialist Gregory Jarvis. Another middle school in Boynton Beach, Florida, is named after deceased teacher/astronaut, Christa McAuliffe. There are also schools in Denver, Colorado, Saratoga, California, Lowell, Massachusetts, and Lenexa, Kansas, named in honor of Christa McAuliffe. The McAuliffe-Shepard Discovery Center, a science museum and planetarium in Concord, New Hampshire, is also partly named in her honor. There is also an elementary school in Germantown, Maryland, named after Christa McAuliffe as well as in Green Bay, Wisconsin and Hastings, Minnesota.[85][86][87] The draw bridge over the barge canal on State Rd.3 on Merritt Island, Florida, is named the Christa McAuliffe Memorial Bridge.[88]
In 2004, President George W. Bush conferred posthumous Congressional Space Medals of Honor to all 14 astronauts lost in the Challenger and Columbia accidents.[89]
In December 2013 the release by Beyoncé Knowles of song XO which begins with a sample of former NASA public affairs officer Steve Nesbitt, recorded moments after the disaster: "Flight controllers here looking very carefully at the situation. Obviously a major malfunction."[90] raised controversy, with former NASA astronauts and families labelling Knowles' sample as "insensitive."[91] Hardeep Phull of New York Post described the sample's presence as "tasteless,"[92] and Keith Cowing of NASA Watch suggested that the usage of the clip ranged from "negligence" to "repugnant."[93] On December 31, 2013, NASA criticized the use of the sample, stating that "The Challenger accident is an important part of our history; a tragic reminder that space exploration is risky and should never be trivialized. NASA works everyday to honor the legacy of our fallen astronauts as we carry out our mission to reach for new heights and explore the universe."[90][93] On December 30, 2013, Knowles issued a statement to ABC News, saying: "My heart goes out to the families of those lost in the Challenger disaster. The song 'XO' was recorded with the sincerest intention to help heal those who have lost loved ones and to remind us that unexpected things happen, so love and appreciate every minute that you have with those who mean the most to you. The songwriters included the audio in tribute to the unselfish work of the Challenger crew with hope that they will never be forgotten."[94]
On July 4, 2014, clothing retailer American Apparel reblogged a photo of the Challenger disaster on its Tumblr account, along with the hashtags "#smoke" and "#clouds" as an apparent attempt to commemorate the American Independence Day. The post was quickly derided across social media. The photo was soon deleted and replaced with an apology and explanation, in which the company blamed the incident on an international social media employee who had been born after the disaster and mistook the photo for fireworks.[95]
Video documentation[edit]
The disaster is notable for the lack of video documentation of the event. Until 2010, the live broadcast of the launch and subsequent disaster by CNN was the only known on-location video footage from within range of the launch site. More recently, as of March 15, 2014, seven other motion picture recordings of the event have become publicly available:
a video recording by Jack Moss from the front yard of his house in Winter Haven, Florida, 80 miles (130 km) from Cape Canaveral[96]
a video recording by Ishbel & Hugh Searle on a plane leaving from Orlando International Airport, 50 miles (80 km) from Cape Canaveral, was posted by their daughter Victoria Searle on January 30, 2011 along with an interview taken on January 28, 2011 by Ishbel & Hugh Searle[97]
a video recording by Bob Karman from Orlando International Airport, 50 miles (80 km) from Cape Canaveral[98]
a Super 8 mm film recorded by then-19-year-old Jeffrey Ault of Orange City, Florida, at the Kennedy Space Center, 10 miles (16 km) from the launch[99]
a video recording by Lawrence Hebert of Electric Sky Films, filmed at the Kennedy Space Center, 10 miles (16 km) from the launch, uncovered in March 2012[100]
a video recording by Steven Virostek uncovered in May 2012[101]
a video recording by Michael and Frances VanKulick of Melbourne, Florida was made public in 2014.[102]
Film[edit]
A BBC docudrama titled The Challenger was broadcast on March 18, 2013, based on the last of Richard Feynman's autobiographical works, What Do You Care What Other People Think?. It stars William Hurt as Feynman.[103][104] It includes the notion that NASA promised the US Air Force that it could launch military payloads on the Shuttle, in order to get funding that would have been earmarked for development of the Titan IV expendable launcher. Numerous delays on previous flights had already reduced NASA's credibility, and after the Challenger disaster, the Air Force developed the Titan IV instead of using the Shuttle.[citation needed]
See also[edit]

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Engineering disasters
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Notes[edit]
1.Jump up ^ Outer Space Universe. "Remembering the Challenger Shuttle Explosion: A Disaster 25 Years Ago". Retrieved January 28, 2011.
2.Jump up ^ Chris Bergin (January 28, 2007). "Remembering the mistakes of Challenger". nasaspaceflight.com. Retrieved August 5, 2011.
3.Jump up ^ "On January 28, 1986, Space Shuttle Challenger Exploded 76 Seconds After Launch (VIDEO)". Viral Video Box. Retrieved January 28, 2014.
4.Jump up ^ "SOLID ROCKET MOTOR JOINT RELIABILITY". NASA Engineering.
5.Jump up ^ Heppenheimer, T. A. (1998). The Space Shuttle Decision. NASA publication SP-4221. pp. 419–420.
6.Jump up ^ McConnell, Malcolm. Challenger: A Major Malfunction, page 118.
7.^ Jump up to: a b c d Rogers Commission (June 6, 1986). "Report of the Presidential Commission on the Space Shuttle Challenger Accident, Chapter VI: An Accident Rooted in History".
8.Jump up ^ "STS-51-L mission archives". NASA.
9.Jump up ^ McConnell, Malcolm. Challenger: A Major Malfunction, pages 150–153.
10.Jump up ^ McConnell, Malcolm. Challenger: A Major Malfunction, page 154.
11.Jump up ^ Rogers Commission (June 6, 1986). "Report of the Presidential Commission on the Space Shuttle Challenger Accident, Chapter II: Events Leading Up to the Challenger Mission". Retrieved January 1, 2007.
12.^ Jump up to: a b c d Berkes, Howard (2012-02-06). "Remembering Roger Boisjoly: He Tried To Stop Shuttle Challenger Launch". All Things Considered. Retrieved February 15, 2012.
13.^ Jump up to: a b c d Rogers Commission (June 6, 1986). "Report of the Presidential Commission on the Space Shuttle Challenger Accident, Chapter V: The Contributing Cause of The Accident". Retrieved 2011-07-12.
14.^ Jump up to: a b Feynman, Richard P. (October 1988). What Do You Care What Other People Think? Further Adventures of a Curious Character. W W Norton. pp. 165–6. ISBN 978-0-393-02659-7.
15.^ Jump up to: a b c d e A major source for information about the Challenger accident is the STS 51-L Incident Integrated Events Timeline developed by the NASA Photo and TV Support Team as part of the Rogers Report. Numerous other timelines have been written based on this information. A detailed transcript of air-to-ground and mission control voice communications was put together by Rob Navias and William Harwood for CBS News, and integrates a timeline of events:By William Harwood (1986). "Voyage Into History Chapter 13: The Timeline". CBS News. Retrieved August 22, 2007.
16.^ Jump up to: a b Rogers Commission (June 6, 1986). "Report of the Presidential Commission on the Space Shuttle Challenger Accident, Volume 3: Appendix N - NASA Photo and TV Support Team Report". Retrieved January 1, 2007.
17.^ Jump up to: a b c Photo and TV Analysis Team Report (1986). Space Shuttle Challenger Accident Investigation. STS-51L Data and Analysis Task Force. Retrieved January 1, 2007.
18.Jump up ^ NASA Mission Archives. "STS-51L". Retrieved January 31, 2010.
19.Jump up ^ Lewis, Richard S. (1988). Challenger: The Final Voyage. Columbia University Press. p. 16. ISBN 0-231-06490-X.
20.^ Jump up to: a b c d Kerwin, Joseph P. (July 28, 1986). "Joseph P. Kerwin to Richard H. Truly". Retrieved July 4, 2006.
21.^ Jump up to: a b Rogers Commission (June 6, 1986). "Report of the Presidential Commission on the Space Shuttle Challenger Accident, Chapter IX: Other Safety Considerations". Retrieved 2011-07-12.
22.^ Jump up to: a b Barbree, Jay (January 1997). "Chapter 5: An eternity of descent". msnbc.com. Retrieved July 29, 2009.
23.Jump up ^ Mullane, Mike (2006). Riding Rockets: The Outrageous Tales of a Space Shuttle Astronaut. Simon and Schuster. p. 245. ISBN 978-0-7432-7682-5. Retrieved 2011-07-12.
24.Jump up ^ Rogers Commission (June 1987). "Implementation of the Recommendations of the Presidential Commission on the Space Shuttle Challenger Accident, Recommendation VII". Retrieved 2011-07-12.
25.Jump up ^ American Rhetoric: Top 100 Speeches of the 20th Century by Rank
26.Jump up ^ http://www.oup.com/us/catalog/he/subject/Communication/SpeechCommunication/PublicSpeaking/?&ci=9780195168051
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66.Jump up ^ Andrews, Gordon C.; John D. Kemper (1999). Canadian Professional Engineering Practice and Ethics (2nd ed.). Toronto: Harcourt Canada. pp. 255–259. ISBN 0-7747-3501-5.
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103.Jump up ^ "BBC - Media Centre - The Challenger". Retrieved 2013-03-18.
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References[edit]
 This article incorporates public domain material from websites or documents of the National Aeronautics and Space Administration.
Boisjoly, Roger. "Ethical Decisions—Morton Thiokol and the Space Shuttle Challenger Disaster: Telecon Meeting". onlineethics.org. Retrieved April 24, 2007.
Columbia Accident Investigation Board (2003). "Report of Columbia Accident Investigation Board". Retrieved 2011-07-12.
Feynman, Richard P. (1986) Rogers Commission Report, Volume 2 Appendix F- Personal Observations on Reliability of Shuttle. (html)
Jensen, Claus. (1996) No Downlink: A Dramatic Narrative about the Challenger Accident and Our Time. New York: Farrar, Straus, Giroux. ISBN 0-374-12036-6.
McConnell, Malcolm. (1987) Challenger: A Major Malfunction. Garden City, NY: Doubleday. ISBN 0-385-23877-0.
M8 Entertainment Inc. (May 24, 2006). "Media 8 To Produce "Challenger" Directed by Philip Kaufman". spaceref.com. Retrieved September 21, 2006.
"Rendez-Vous Houston". jarreuk.com. Retrieved November 19, 2006.
Riffe, Daniel; James Glen Stoval (Autumn 1989). "Diffusion of News of Shuttle Disaster: What Role for Emotional Response?". Journalism Quarterly (Association for education in journalism and mass communication).
Rogers Commission (June 6, 1986). "Report of the Presidential Commission on the Space Shuttle Challenger Accident". Retrieved 2011-07-12.
Rogers Commission (June 1987). "Implementation of the Recommendations of the Presidential Commission on the Space Shuttle Challenger Accident". Retrieved January 1, 2007.
Vaughan, Diane. (1996) The Challenger Launch Decision: Risky Technology, Culture and Deviance at NASA. Chicago: University of Chicago Press. ISBN 0-226-85176-1.
Wallace, Brendan & Ross, Alastair (2006) Beyond Human Error. Florida: CRC Press. ISBN 978-0-8493-2718-6
Wright, John C.; Dale Kunkel; Marites Pinon; Aletha C. Huston (Spring 1989). "How Children Reacted to Televised Coverage of the Space Shuttle Disaster". Journal of Communication 39 (2).
Boisjoly, Roger. "Ethical Decisions - Morton Thiokol and the Challenger Disaster: Telecon Meeting". onlineethics.org. Retrieved 2010-05-18.
Further reading[edit]
Evans, Ben (2007). Space shuttle challenger: ten journeys into the unknown. Published in association with Praxis Pub. ISBN 978-0-387-46355-1. Retrieved 2011-07-12
Pinkus, Rosa Lynn (1997). Engineering Ethics: Balancing Cost, Schedule, and Risk. Cambridge University Press. ISBN 0-521-43171-9.
Schwartz, Howard S. (1990). Narcissistic Process and Corporate Decay: The Theory of the Organization Ideal. NYU Press. ISBN 0-8147-7938-7.
External links[edit]
 Wikimedia Commons has media related to Space Shuttle Challenger disaster.

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Challenger disaster: remembered. The Boston Globe. January 28, 2011.
Complete text and audio and video of Ronald Reagan's Shuttle Challenger Address to the Nation AmericanRhetoric.com
Space Shuttle Challenger Tragedy - video of shuttle launch and Reagan's address - YouTube
January 29, 1986 newspaper
NASA History Office. "Challenger STS 51-L Accident". NASA. Retrieved November 20, 2006.
NASA Kennedy Space Center. "Sequence of Major Events of the Challenger Accident". NASA. Retrieved 2011-07-12.
Harwood, William; Rob Navias. "Challenger timeline". Spaceflight Now. Retrieved November 20, 2006.
CBS Radio news Bulletin of the Challenger Disaster Anchored by Christopher Glenn from January 28, 1986 Part 1 (mp3),
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Part 4 (mp3).

Coordinates: 28°38′24″N 80°16′48″W


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1993 World Trade Center bombing
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1993 World Trade Center bombing
WTC 1993 ATF Commons.jpg
Underground damage after the bombing

Location
World Trade Center, New York, NY 10048
Coordinates
40.711452°N 74.011919°WCoordinates: 40.711452°N 74.011919°W
Date
February 26, 1993
 12:17:37 p.m. (UTC-05:00)
Target
World Trade Center

Attack type
 Truck bombing, terrorism, mass murder
Deaths
6

Non-fatal injuries
 1,042
Perpetrators
Ramzi Yousef and co-conspirators
Motive
US support of Israel


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On February 26, 1993, a truck bomb was detonated below the North Tower of the World Trade Center in New York City. The 1,336 pounds (606 kg) urea nitrate–hydrogen gas enhanced device[1] was intended to knock the North Tower (Tower One) into the South Tower (Tower Two), bringing both towers down and killing tens of thousands of people.[2][3] It failed to do so, but did kill six people and injured more than a thousand.[4] The attack was planned by a group of terrorists including Ramzi Yousef, Mahmud Abouhalima, Mohammad Salameh, Nidal A. Ayyad, Abdul Rahman Yasin and Ahmad Ajaj. They received financing from Khaled Sheikh Mohammed, Yousef's uncle. In March 1994, four men were convicted of carrying out the bombing: Abouhalima, Ajaj, Ayyad and Salameh. The charges included conspiracy, explosive destruction of property, and interstate transportation of explosives. In November 1997, two more were convicted: Ramzi Yousef, the mastermind behind the bombings, and Eyad Ismoil, who drove the truck carrying the bomb.


Contents  [hide]
1 Planning and organization 1.1 Yousef's view of the attack
2 The attack 2.1 Bomb characteristics
3 Investigation
4 Aftermath 4.1 Memorial
4.2 FBI involvement
4.3 U.S. Diplomatic Security Service (DSS) involvement
4.4 Allegations of Iraqi involvement
4.5 Improved security
5 Legal responsibility
6 See also
7 References
8 External links

Planning and organization[edit]
Ramzi Yousef, who was born as Abdul Basit Mahmoud Abdul Karim in Kuwait, spent time at Al-Qaeda training camps in Afghanistan,[5] before beginning in 1991 to plan a bombing attack within the United States. Yousef's uncle Khalid Shaikh Mohammed Ali Fadden, who later was considered the principal architect of the September 11 attacks, gave him advice and tips over the phone, and funded his co-conspirator Mohammed Salameh with a US$660 wire transfer.[6]
Yousef arrived illegally in the United States on September 1, 1992, traveling with Ahmed Ajaj from Pakistan, though both sat apart on the flight and acted as though they were traveling separately. Ajaj tried to enter with a forged Swedish passport, though it had been altered and thus raised suspicions among INS officials at John F. Kennedy International Airport. When officials put Ajaj through secondary inspection, they discovered bomb making instructions and other materials in his luggage, and arrested him. The name Abu Barra, an alias of Mohammed Jamal Khalifa, appeared in the manuals. Yousef tried to enter with a false Iraqi passport, claiming political asylum. Yousef was allowed into the United States, and was given a hearing date.[7]
Yousef set up residence in Jersey City, New Jersey, traveled around New York and New Jersey and called Sheikh Omar Abdel Rahman, a controversial blind Muslim cleric, via cell phone. After being introduced to his co-conspirators by Abdel Rahman at the latter's Al-Farooq Mosque in Brooklyn, Yousef began assembling the 1,500 lb (680 kg) urea nitrate–hydrogen gas enhanced device for delivery to the WTC. He ordered chemicals from his hospital room when injured in a car crash – one of three accidents caused by Salameh in late 1992 and early in 1993.
El Sayyid Nosair, one of the blind sheikh's men, was arrested in 1991 for the murder of Rabbi Meir Kahane. According to prosecutors, "the Red" Mahmud Abouhalima, also convicted in the bombing, told Wadih el Hage to buy the .357 caliber revolver used by Nosair in the Kahane shooting. In the initial court case in NYS Criminal Court Nosair was acquitted of murder but convicted of gun charges (in a related and follow-up case in Federal Court, he was convicted). Dozens of Arabic bomb-making manuals and documents related to terrorist plots were found in Nosair's New Jersey apartment, with manuals from Army Special Warfare Center at Fort Bragg, North Carolina, secret memos linked to Joint Chiefs of Staff, and 1,440 rounds of ammunition. (Lance 2004 26)
Yousef's view of the attack[edit]
According to the journalist Steve Coll, Yousef mailed letters to various New York newspapers just before the attack, in which he claimed he belonged to 'Liberation Army, Fifth Battalion'.[8] These letters made three demands: an end to all US aid to Israel, an end to US diplomatic relations with Israel, and a pledge by the United States to end interference "with any of the Middle East countries' interior affairs." He stated that the attack on the World Trade Center would be merely the first of such attacks if his demands were not met. In his letters Yousef admitted that the World Trade Center bombing was an act of terrorism, but this was justified because "the terrorism that Israel practices (which America supports) must be faced with a similar one."
The attack[edit]



 Image of the procession of rescue vehicles responding to the 1993 World Trade Center bombing. One World Trade Center is on the far right of the frame.


 Depiction of blast damage
On Friday, February 26, 1993, Ramzi Yousef and a Jordanian friend, Eyad Ismoil, drove a yellow Ryder van into Lower Manhattan, and pulled into the public parking garage beneath the World Trade Center around noon. They parked on the underground B-2 level. Yousef ignited the 20-foot fuse, and fled. Twelve minutes later, at 12:17:37 pm, the bomb exploded in the underground garage, generating an estimated pressure of 150,000 psi.[9] The bomb opened a 30-m (98 ft) wide hole through four sublevels of concrete. The detonation velocity of this bomb was about 15,000 ft/s (4.5 km/s). Initial news reports indicated a main transformer may have blown, not realizing a bomb had exploded in the basement.
The bomb instantly cut off the World Trade Center's main electrical power line, knocking out the emergency lighting system. The bomb caused smoke to rise up to the 93rd floor of both towers, including through the stairwells which were not pressurized.[10] With thick smoke filling the stairwells, evacuation was difficult for building occupants and led to many smoke inhalation injuries. Hundreds were trapped in elevators in the towers when the power was cut, including a group of 17 kindergartners, on their way down from the South Tower observation deck, who were trapped between the 35th and 36th floors for five hours.[11][12]
Also as a result of the loss of power most of New York City's radio and television stations lost their over-the-air broadcast signal for almost a week, with television stations only being able to broadcast via cable and satellite via a microwave hookup between the stations and three of the New York area's largest cable companies, Cablevision, Comcast, and Time Warner Cable. Telephone service for much of Lower Manhattan was also disrupted.
All together, six people were killed and 1,042 others injured, most during the evacuation that followed the blast.[13] A report from the US Fire Administration states that "Among the scores of people who fled to the roofs of the towers, 28 with medical problems were airlifted by New York City police helicopters (...)". It is known that 15 people received traumatic injury from the blast and 20 complained of cardiac problems. One firefighter was hospitalized, while 87 others, 35 police officers, and an EMS worker were also injured in dealing with the fires and other aftermath.[14]
The plan was that if the bomb truck was parked at the right place, the North Tower would fall onto the South Tower, collapsing them both. However, the tower did not collapse, according to Yousef's plan, but the garage was severely damaged in the explosion. Nevertheless, had the van been parked closer to the WTC's poured concrete foundations, Yousef's plan might have succeeded.[15] He escaped to Pakistan several hours after the bombing.
Due to the time at which Yousef left Jersey City, questions linger as to why he waited until noon to attack when the parking area was much less crowded.[citation needed] Conspirator Mahmud Abouhalima later stated that the original plan was to attack the United Nations headquarters earlier in the morning.[citation needed] Author Simon Reeve theorized that something went wrong, such as Yousef encountering too much security, and the target was changed to be the World Trade Center.[13]
Bomb characteristics[edit]


 This section needs additional citations for verification. Please help improve this article by adding citations to reliable sources. Unsourced material may be challenged and removed. (February 2011)
Yousef was assisted by Iraqi bomb maker Abdul Rahman Yasin, who helped assemble the complex 1,310-pound (590 kg) bomb, which was made of a urea nitrate main charge with aluminum, magnesium and ferric oxide particles surrounding the explosive. The charge used nitroglycerine, ammonium nitrate dynamite, smokeless powder and fuse as booster explosives.[16] Three tanks of bottled hydrogen were also placed in a circular configuration around the main charge, to enhance the fireball and afterburn of the solid metal particles.[17] The use of compressed gas cylinders in this type of attack closely resembles the 1983 Beirut barracks bombing 10 years earlier. Both of these attacks used compressed gas cylinders to create fuel-air and thermobaric bombs[18] that release more energy than conventional high explosives. According to testimony in the bomb trial, only once before the 1993 attack had the FBI recorded a bomb that used urea nitrate.[19][20]
The Ryder van used in the bombing had 295 cubic feet (8.4 m3) of space, which would hold up to 2,000 pounds (910 kg) of explosives. However, the van was not filled to capacity. Yousef used four 20 ft (6 m) long fuses, all covered in surgical tubing. Yasin calculated that the fuse would trigger the bomb in twelve minutes after he had used a cigarette lighter to light the fuse.
Yousef wanted the smoke to remain in the tower, therefore catching the public eye by smothering people inside, killing them slowly. He anticipated Tower One collapsing onto Tower Two after the blast.
There remains a popular belief that there was cyanide in the bomb, which is reinforced by Judge Duffy's statement at sentencing, "You had sodium cyanide around, and I’m sure it was in the bomb." However, the bomb's true composition was not able to be ascertained from the crime scene and Robert Blitzer, a senior FBI official who worked on the case, stated that there was "no forensic evidence indicating the presence of sodium cyanide at the bomb site." Furthermore, Yousef is said only to have considered adding cyanide to the bomb, and to have regretted not doing so in Peter Lance's book 1000 Years for Revenge.
Investigation[edit]


 This section needs additional citations for verification. Please help improve this article by adding citations to reliable sources. Unsourced material may be challenged and removed. (February 2011)
Though the cause of the blast was not immediately known, with some suspecting a transformer explosion, agents and bomb technicians from the ATF, FBI, and the NYPD quickly responded to the scene. The magnitude of the explosion was far beyond that of a transformer explosion.
In the days after the bombing, investigators surveyed the damage and looked for clues. About 300 FBI agents were deployed under the codename TRADEBOM.[21] While combing through the rubble in the underground parking area, a bomb technician located some internal component fragments from the vehicle that delivered the bomb. A vehicle identification number (VIN), found on a piece from an axle, gave investigators crucial information that led them to a Ryder truck rental outlet in Jersey City. Investigators determined that the vehicle had been rented by Mohammad Salameh, one of Yousef's co-conspirators.[22] Salameh had reported the van stolen, and when he returned on March 4, 1993, to get his deposit back, authorities arrested him.[23]
Salameh's arrest led police to the apartment of Abdul Rahman Yasin in Jersey City, New Jersey, which Yasin was sharing with his mother, in the same building as Ramzi Yousef's apartment. Yasin was taken to the FBI's Newark field office in Newark, New Jersey, and was then released. The next day, he flew back to Iraq, via Amman, Jordan. Yasin was later indicted for the attack, and in 2001 he was placed on the initial list of the FBI Most Wanted Terrorists, on which he remains today. He disappeared before the U.S. coalition invasion, Operation Iraqi Freedom, in 2003. In March 1994, Salameh, Nidal Ayyad, Mahmud Abouhalima and Ahmad Ajaj were each convicted in the World Trade Center bombing. In May 1994, they were sentenced to life imprisonment.
The capture of Salameh and Yasin led authorities to Ramzi Yousef's apartment, where they found bomb-making materials and a business card from Mohammed Jamal Khalifa. Khalifa was arrested on December 14, 1994, and was deported to Jordan by the INS on May 5, 1995. He was acquitted by a Jordanian court and lived as a free man in Saudi Arabia until his death in 2007. In 2002, it was made public that Yasin, the only person involving in the bombing who was never caught by US authorities,[24] was being held as a prisoner on the outskirts of Baghdad, Iraq since 1994.[24] When journalist Leslie Stahl interviewed him there for a segment on 60 Minutes on May 23, 2002 [24] Yasin appeared in prison pajamas and handcuffs.[24] Yasin has not been seen or heard from since the interview. He was not located during the 2003 invasion of Iraq.
Aftermath[edit]
Memorial[edit]



 The names of the six victims of the attack are inscribed in panel N-73 of the North Pool at the National September 11 Memorial, where the North Tower formerly stood.
The bombing claimed the following six victims:
Monica Rodrigues Smith age 36, a secretary, who was seven months pregnant, was in her office checking time sheets in the B-2 level.
Robert (Bob) Kirkpatrick, age 61, Senior Structural Maintenance Supervisor.
Bill Macko, age 57, General Maintenance Supervisor, Mechanical Section.
Stephen Knapp, age 47, Chief Maintenance Supervisor, Mechanical Section . Kirkpatrick, Macko and Knapp were eating lunch together in a room next to Smith's office at the time of the bombing.
John DiGiovanni, age 45, a dental products salesperson, was parking in the underground garage.
Wilfredo Mercado, age 37, a receiving agent for Windows on the World restaurant, was checking in deliveries.
A granite memorial fountain honoring the victims of the bombing was designed by Elyn Zimmerman and dedicated in 1995 on Austin J. Tobin Plaza, directly above the site of the explosion. It contained the names of the six adults who were killed in the attack as well as an inscription that read:
"On February 26, 1993, a bomb set by terrorists exploded below this site. This horrible act of violence killed innocent people, injured thousands, and made victims of us all."[25]
The fountain was destroyed with the rest of the World Trade Center during the September 11 attacks. A recovered fragment from the 1993 bombing memorial with the text "John D", from bombing victim John DiGiovanni, was later incorporated into a temporary memorial designed by Port Authority architect Jacqueline Hanley, and erected on the Liberty Street side of the site following the September 11 attacks. The memorial was visible across a fence barrier but was not open to the public.[26]
At the National 9/11 Memorial, which opened on the tenth anniversary of the 2001 attacks, the six adult victims of the 1993 bombing are memorialized at the North Pool, on Panel N-73.[27]
FBI involvement[edit]
[icon] This section requires expansion. (May 2013)
In the course of the trial it was revealed that the FBI had an informant, a former Egyptian army officer named Emad Salem. Salem claims to have informed the FBI of the plot to build a bomb that would eventually be used in the World Trade Center towers as early as February 6, 1992. Salem's role as informant allowed the FBI to quickly pinpoint the conspirators out of hundreds of possible suspects. The transcripts do not make clear the extent to which Federal Authorities knew that there was a plan to bomb the World Trade Center, merely that a bombing of some sort was being discussed.
Salem claimed that the FBI's plan was for Salem to supply the conspirators with a harmless powder instead of actual explosive to build their bomb, but that the FBI chose to use him for other purposes instead. He secretly recorded hundreds of hours of telephone conversations with his FBI handlers.[28]
U.S. Diplomatic Security Service (DSS) involvement[edit]



 Aftermath of the bombing, photographed by DSS agents
Although the FBI received the credit, Diplomatic Security Service special agents actually found and arrested Ramzi Ahmed Yousef, the architect of the 1993 World Trade Center bombing. Special Agents Bill Miller and Jeff Riner were given a tip by an associate of Ramzi Yousef about his location. In coordination with the Pakistani Inter-Services Intelligence (ISI), DSS arrested Yousef.[29] Security ranged for the World Trade from WTC security guards to car barriers which would not allow cars to enter certain areas. The New York Port Authority was to govern as the main security for the World Trade buildings. All packages were scanned at various checkpoints then sent up to the proper addressee. After his arrest, Ramzi Yousef is alleged to have said to investigators "this is only the beginning."
Allegations of Iraqi involvement[edit]
In October 2001 in a PBS interview, former CIA Director James Woolsey claimed that Ramzi Yousef worked for Iraqi intelligence.[30] He suggested the grand jury investigation turned up evidence pointing to Iraq that the Justice Department "brushed aside." But Neil Herman, who headed the FBI investigation, noted "The one glaring connection that can't be overlooked is Yasin. We pursued that on every level, traced him to a relative and a location, and we made overtures to get him back." However, Herman says that Yasin's presence in Baghdad does not mean Iraq sponsored the attack: "We looked at that rather extensively. There were no ties to the Iraqi government." CNN terrorism reporter Peter L. Bergen writes, "In sum, by the mid-'90s, the Joint Terrorism Task Force in New York, the F.B.I., the U.S. Attorney's office in the Southern District of New York, the C.I.A., the N.S.C., and the State Department had all found no evidence implicating the Iraqi government in the first Trade Center attack."[31]
Claims of direct Iraqi involvement come from Dr.Laurie Mylroie of the American Enterprise Institute and former associate professor of the U.S. Naval War College, with the claims rejected by others. CNN reporter Peter Bergen has called her a "crackpot" who claimed that "Saddam was not only behind the '93 Trade Center attack, but also every anti-American terrorist incident of the past decade, from the bombings of U.S. embassies in Kenya and Tanzania to the leveling of the federal building in Oklahoma City to September 11 itself."[31] Daniel Benjamin, a senior fellow at the Center for Strategic and International Studies, writes: "The most knowledgeable analysts and investigators at the CIA and at the FBI believe that their work conclusively disproves Mylroie's claims."[32] Dr. Robert Leiken of the Nixon Center comments on the lack of evidence in her work: "Laurie has discovered Saddam's hand in every major attack on US interests since the Persian Gulf War, including U.S. embassies in Kenya and Tanzania and even the federal building in Oklahoma City. These allegations have all been definitively refuted by the FBI, the National Transportation Safety Board (NTSB) and other investigatory bodies...."[33]
In March 2008, the Pentagon released its study of some 600,000 documents captured in Iraq after the 2003 invasion (see 2008 Pentagon Report). The study "found no 'smoking gun' (i.e., direct connection) between Saddam's Iraq and al Qaeda."[34] Among the documents released by the Pentagon was a captured audio file of Saddam Hussein speculating that the 1993 attack on the World Trade Center had been carried out by Israel or American intelligence, or perhaps a Saudi or Egyptian faction. Saddam said that he did not trust the bomber Yasin, who was in Iraqi custody, because his testimony was too "organized." The Pentagon study found that Yasin "was a prisoner, and not a guest, in Iraq."[35] Mylroie denied that this was proof of Saddam's non-involvement, claiming that "one common purpose of such meetings was to develop cover stories for whatever Iraq sought to conceal."[36]
Improved security[edit]
In the wake of the bombing and the chaotic evacuation which followed, the World Trade Center and many of the firms inside of it revamped emergency procedures, particularly with regard to evacuation of the towers. These policies played a role in evacuating the building during the September 11th attacks, which destroyed the towers.
Free access to the roofs, which had enabled the evacuation by police helicopter in the 1993 bombing, was ended soon after.[citation needed]
Legal responsibility[edit]
The victims of the 1993 World Trade Center bombings sued the Port Authority of New York and New Jersey for damages. A decision was handed down in 2006, assigning liability for the bombings to the Port Authority. The decision declared that the agency was 68 percent responsible for the bombing, and the terrorists bore only 32 percent of the responsibility. In January 2008, the Port Authority asked a five-judge panel of the Appellate Division of the New York State Supreme Court in Manhattan to throw out the decision, describing the jury's verdict as "bizarre".[37] On April 29, 2008, a New York State Appeals Court unanimously upheld the jury's verdict. Under New York law once a defendant is more than 50 percent at fault, he/she/it can be held fully financially liable.[38]
It has been argued that the problem with the apportionment of responsibility in the case is not the jury's verdict, but rather New York's tort-reform-produced state apportionment law. Traditionally, courts do not compare intentional and negligent fault. The Restatement Third of Torts: Apportionment of Liability recommends a rule to prevent juries from having to make comparisons like the terrorist-Port Authority comparison in this case. However, if a jurisdiction does compare these intentional and negligent torts, courts' second-best position is to do what the NYS Appeals Court did—to uphold all jury apportionments, even those that assign greater, or perhaps far greater, responsibility to negligent than intentional parties.[39]
See also[edit]


Flag of New York City.svgNew York City portal
 National Park Service 9-11 Statue of Liberty and WTC fire.jpgTerrorism portal
 Alcatel 9109HA.png1990s portal
 

September 11 attacks
1993 shootings at CIA Headquarters
Oklahoma City bombing
Bojinka plot
References[edit]
Notes:
1.Jump up ^ Whitlock, Craig (2005-07-05). "Homemade, Cheap and dangerous – Terror Cells Favor from Simple Ingredients In Building Bombs". Washington Post. Retrieved 9 September 2009.
2.Jump up ^ Childers, J. Gilmore; Henry J. DePippo (1998-02-24). "Senate Judiciary Committee Hearings: Foreign Terrorists in America: Five Years After the World Trade Center". US Senate Judiciary Committee. Archived from the original on 2007-12-27. Retrieved 2008-01-08.
3.Jump up ^ Wright, Lawrence, Looming Tower, Knopf, (2006) p. 178.
4.Jump up ^ "FBI 100 First Strike: Global Terror in America". FBI.gov. Retrieved 2011-09-08.
5.Jump up ^ Wright (2006), Chapter 9.
6.Jump up ^ "Khalid Sheikh Mohammed". GlobalSecurity.org. Archived from the original on 21 October 2008. Retrieved 2008-10-26.
7.Jump up ^ "Foreign Terrorists in America". 1998 Congressional Hearings – Intelligence and Security. Federation of American Scientists. 1998-02-24. Retrieved 2008-10-27.
8.Jump up ^ Coll, Steve (2004). Ghost Wars: The Secret History of the CIA, Afghanistan, and Bin Laden, from the Soviet Invasion to September 10, 2001. The Penguin Press HC. ISBN 1-59420-007-6.
9.Jump up ^ Reeve (1999), p. 10.
10.Jump up ^ Barbanel, Josh (1993-02-27). "Tougher Code May Not Have Helped". The New York Times. Retrieved 9 September 2009.
11.Jump up ^ Mathews, Tom (1993-03-08). "A Shaken City's Towering Inferno". Newsweek. Archived from the original on 30 October 2008. Retrieved 2008-10-26.
12.Jump up ^ Stone, Andrea (1993-03-01). "A major calamity, a lot of fear". USA Today.
13.^ Jump up to: a b Reeve (1999), p. 15.
14.Jump up ^ "The World Trade Center Bombing: Report and Analysis". US Fire Administration, DHS. February 1993. Retrieved 2011-10-25.
15.Jump up ^ "An Icon Destroyed". MSNBC. 2003. Archived from the original on 2005-03-16.
16.Jump up ^ "Abdul Rahman Yasin". Most Wanted Terrorists. Federal Bureau of Investigation. Archived from the original on 14 October 2008. Retrieved 2008-10-26.
17.Jump up ^ "Foreign Terrorists In America". Federation of American Scientists. Retrieved 2008-10-26.
18.Jump up ^ Paul Rogers(2000) Politics in the Next 50 Years: The Changing Nature of International Conflict.
19.Jump up ^ "Urea nitrate rarely used as explosive."
20.Jump up ^ Alternate link: If you get a 403 server error, try this link and then click on the link for "Page 16335".
21.Jump up ^ Poveda, Tony; Powers, Richard; Rosenfeld, Susan; Theoharis, Athan G. The FBI: A Comprehensive Reference Guide. Greenwood. p. 94. ISBN 978-0897749916.
22.Jump up ^ Reeve (1999), pp. 27–32.
23.Jump up ^ Reeve (1999), pp. 32–26.
24.^ Jump up to: a b c d 60 Minutes (2002-05-31). "60 Minutes: The Man Who Got Away". 60 Minutes. Retrieved 2012-02-04.
25.Jump up ^ "9/11 Living Memorial - 1993 WTC Bombing - Memorials". Voices of September 11th. Retrieved March 10, 2012.
26.Jump up ^ "WTC Memorial for '93 victims unveiled". Downtown Express. 2005. Retrieved 9 September 2009.
27.Jump up ^ "North Pool: Panel N-73". National September 11 Memorial & Museum. Retrieved December 9, 2011.
28.Jump up ^ Blumenthal, Ralph (1993-10-28). "Tapes Depict Proposal to Thwart Bomb Used in Trade Center Blast". New York Times. p. Section A, Page 1, Column 4. Retrieved 2008-10-26.
29.Jump up ^ Katz, Samuel M. "Relentless Pursuit: The DSS and the manhunt for the al-Qaeda terrorists", 2002.
30.Jump up ^ "Interviews: R. James Woolsey". Frontline: Gunning for Saddam. PBS. Archived from the original on 29 October 2008. Retrieved 2008-10-16.
31.^ Jump up to: a b Bergen, Peter (December 2003). "Armchair Provocateur". Washington Monthly. Archived from the original on 1 November 2008. Retrieved 2008-10-26.
32.Jump up ^ Benjamin, Daniel and Steven Simon (2005). The Next Attack. Times Books. p. 145. ISBN 0-8050-7941-6.
33.Jump up ^ Glazov, Jamie (2005-02-11). "The Saddam-Osama Connection: Part II". FrontPageMagazine.com. Retrieved 2008-10-26.
34.Jump up ^ Woods, Kevin M. and James Lacey (November 2007). "Saddam and Terrorism: Emerging Insights from Captured Iraqi Documents – Executive Summary; Volume 1" (PDF). Institute for Defense Analysis / Federation of American Scientists. pp. 16, 18, 51. Archived from the original on 31 October 2008. Retrieved 2008-10-26.
35.Jump up ^ Eli Lake, Report Details Saddam's Terrorist Ties, New York Sun, March 14, 2008.
36.Jump up ^ Laurie Mylroie, More To Uncover on Saddam, New York Sun, April 2, 2008.
37.Jump up ^ Hartocollis, Anemona (2008-01-14). "Blame for 1993 Attack at Center Is Still at Issue". New York Times. Archived from the original on 9 December 2008. Retrieved 2008-10-26.
38.Jump up ^ Hartocollis, Anemona (2008-04-30). " "Port Authority Liable in 1993 Trade Center Attack". The New York Times. Retrieved 2008-10-26.
39.Jump up ^ Ellen M. Bublick, Upside Down? Terrorists, Proprietors and Responsibility for Criminal Harm in the Post-9/11 Tort-Reform World.
Sources:
Lance, Peter (2003). 1000 Years for Revenge. HarperCollins.
Reeve, Simon (1999). The New Jackals: Ramzi Yousef, Osama bin Laden and the Future of Terrorism. Northeastern University Press.
Wright, Lawrence (2006). The Looming Tower: Al Qaeda and the Road to 9/11. Alfred A. Knopf. ISBN 0-375-41486-X.
External links[edit]
 Wikimedia Commons has media related to 1993 World Trade Center bombing.
Rewards for Justice World Trade Center Bombing page
"1993: World Trade Center bomb terrorises New York", BBC: On This Day
FBI – 1993 World Trade Center Bombing – Press Room FBI February 26, 2008
Images from the 1993 World Trade Center Bombing
WCBS 880 radio aircheck, February 26, 1993 at sorabji.com
A fire dispatcher's perspective from FDNewYork.com


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Categories: 1993 murders in the United States
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September 11 attacks
From Wikipedia, the free encyclopedia
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"9/11" redirects here. For the date, see September 11 or 9 November.
For other uses, see September 11 attacks (disambiguation).
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September 11 attacks
A montage of eight images depicting, from top to bottom, the World Trade Center towers burning, the collapsed section of the Pentagon, the impact explosion in the south tower, a rescue worker standing in front of rubble of the collapsed towers, an excavator unearthing a smashed jet engine, three frames of video depicting airplane hitting the Pentagon.
Top to bottom, left to right
The Twin Towers of the World Trade Center on fire;
A section of the Pentagon collapses;
Flight 175 crashes into 2 WTC;
A fireman requests help at Ground Zero;
An engine from Flight 93 is recovered;
Flight 77's collision with the Pentagon as captured
 by CCTV.


Location
New York City;
Arlington County, Virginia;
vicinity of Shanksville, Pennsylvania

Date
Tuesday, September 11, 2001
8:46 – 10:28 am (UTC-4)

Attack type

Aircraft hijackings
Suicide attacks
Mass murder
Terrorism

Deaths
2,996  (2,977 victims, 19 hijackers)

Non-fatal injuries
 6,000+
Perpetrators
Al-Qaeda[1] (see also responsibility and hijackers)

The September 11 attacks (also referred to as September 11, September 11th, or 9/11)[nb 1] were a series of four coordinated terrorist attacks launched by the Islamic terrorist group al-Qaeda upon the United States in New York City and the Washington, D.C., metropolitan area on Tuesday, September 11, 2001. The attacks killed almost 3,000 people and caused at least $10 billion in property and infrastructure damage.[2]
Four passenger airliners were hijacked by 19 al-Qaeda terrorists so they could be flown into buildings in suicide attacks. Two of those planes, American Airlines Flight 11 and United Airlines Flight 175, were crashed into the North and South towers, respectively, of the World Trade Center complex in New York City. Within two hours, both towers collapsed with debris and the resulting fires causing partial or complete collapse of all other buildings in the WTC complex, as well as significant damage to ten other large surrounding structures. A third plane, American Airlines Flight 77, was crashed into the Pentagon (the headquarters of the United States Department of Defense), leading to a partial collapse in its western side. The fourth plane, United Airlines Flight 93, was targeted at Washington, D.C.,[3] but crashed into a field near Shanksville, Pennsylvania, after its passengers tried to overcome the hijackers. In total, almost 3,000 people died in the attacks, including the 227 civilians and 19 hijackers aboard the four planes. It also was the deadliest incident for firefighters and for law enforcement officers[4][5] in the history of the United States, with 343 and 72 killed respectively.
Suspicion quickly fell on al-Qaeda. Although the group's leader, Osama bin Laden, initially denied any involvement, in 2004, he claimed responsibility for the attacks.[1] Al-Qaeda and bin Laden cited U.S. support of Israel, the presence of U.S. troops in Saudi Arabia, and sanctions against Iraq as motives for the attacks. The United States responded to the attacks by launching the War on Terror and invading Afghanistan to depose the Taliban, which had harbored al-Qaeda. Many countries strengthened their anti-terrorism legislation and expanded law enforcement powers. Having evaded capture for years, bin Laden was located and killed by U.S. forces in May 2011.
The destruction of the Twin Towers and other properties caused serious damage to the economy of Lower Manhattan and had a significant effect on global markets, closing Wall Street until September 17 and the civilian airspace in the U.S. and Canada until September 13. Many closings, evacuations, and cancellations followed the attack, either out of fear of further attacks or respect for the tragedy. Cleanup of the World Trade Center site was completed in May 2002, and the Pentagon was repaired within a year. Numerous memorials have been constructed, including the National September 11 Memorial & Museum in New York, the Pentagon Memorial, and the Flight 93 National Memorial in Pennsylvania.
On November 18, 2006, construction of One World Trade Center began at the World Trade Center site.[6] As of September 2013, the new tower's concrete construction was largely complete, and will officially open when the installation of podium glass and interior construction is completed, estimated mid-2014.[7]


Contents  [hide]
1 Background 1.1 Attackers 1.1.1 al-Qaeda
1.1.2 Osama bin Laden
1.1.3 Khalid Sheikh Mohammed
1.1.4 Other al-Qaeda members
1.2 Motives
1.3 Planning of the attacks
2 Attacks 2.1 Events
2.2 Casualties
2.3 Damage
2.4 Rescue efforts
3 Aftermath 3.1 Immediate response
3.2 Domestic reactions 3.2.1 Hate crimes
3.2.2 Muslim American response
3.3 International reactions
3.4 Military operations
4 Effects 4.1 Health issues
4.2 Weather
4.3 Economic
4.4 Cultural
4.5 Government policies toward terrorism
5 Investigations 5.1 FBI
5.2 CIA
5.3 9/11 Commission
5.4 Collapse of the World Trade Center
6 Reconstruction
7 Memorials
8 See also
9 Citations 9.1 Notes
9.2 References
9.3 Bibliography
9.4 Further reading
10 External links

Background
Attackers
Further information: Responsibility for the September 11 attacks, Hijackers in the September 11 attacks, Trials related to the September 11 attacks and 20th hijacker
al-Qaeda


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Attacks by al-Qaeda





Further information: Al-Qaeda
The origins of al-Qaeda can be traced to 1979 when the Soviet Union invaded Afghanistan. Osama bin Laden traveled to Afghanistan and helped organize Arab mujahideen to resist the Soviets.[8] Under the guidance of Ayman al-Zawahiri, bin Laden became more radical.[9] In 1996, bin Laden issued his first fatwā, calling for American soldiers to leave Saudi Arabia.[10]
In a second fatwā in 1998, bin Laden outlined his objections to American foreign policy with respect to Israel, as well as the continued presence of American troops in Saudi Arabia after the Gulf War.[11] Bin Laden used Islamic texts to exhort Muslims to attack Americans until the stated grievances are reversed, and according to bin Laden, Muslim legal scholars, "have throughout Islamic history unanimously agreed that the jihad is an individual duty if the enemy destroys the Muslim countries."[11]
Osama bin Laden
Further information: Osama bin Laden, Death of Osama bin Laden and Videos of Osama bin Laden



 1997 picture of Osama bin Laden
Bin Laden, who orchestrated the attacks, initially denied but later admitted involvement.[1][12][13] Al Jazeera broadcast a statement by bin Laden on September 16, 2001, stating, "I stress that I have not carried out this act, which appears to have been carried out by individuals with their own motivation."[14] In November 2001, U.S. forces recovered a videotape from a destroyed house in Jalalabad, Afghanistan. In the tape, bin Laden is seen talking to Khaled al-Harbi and admits foreknowledge of the attacks.[15] On December 27, 2001, a second bin Laden video was released. In the video, he said, "It has become clear that the West in general and America in particular have an unspeakable hatred for Islam....It is the hatred of crusaders. Terrorism against America deserves to be praised because it was a response to injustice, aimed at forcing America to stop its support for Israel, which kills our people...We say that the end of the United States is imminent, whether Bin Laden or his followers are alive or dead, for the awakening of the Muslim umma (nation) has occurred", but he stopped short of admitting responsibility for the attacks.[16] The transcript references several times to the United States specifically targeting Muslims.
Shortly before the U.S. presidential election in 2004, in a taped statement, bin Laden publicly acknowledged al-Qaeda's involvement in the attacks on the U.S. and admitted his direct link to the attacks. He said that the attacks were carried out because, "we are free ... and want to regain freedom for our nation. As you undermine our security we undermine yours."[17] Bin Laden said he had personally directed his followers to attack the World Trade Center.[13][18] Another video obtained by Al Jazeera in September 2006 shows bin Laden with Ramzi bin al-Shibh, as well as two hijackers, Hamza al-Ghamdi and Wail al-Shehri, as they make preparations for the attacks.[19] The U.S. never formally indicted bin Laden for the 9/11 attacks but he was on the FBI's Most Wanted List for the bombings of the U.S. Embassies in Dar es Salaam, Tanzania, and Nairobi, Kenya.[20][21] After a nearly 10-year manhunt, bin Laden was killed by American special forces in a compound in Abbottabad, Pakistan on May 2, 2011.[22][23]
Khalid Sheikh Mohammed
Main article: Khalid Sheikh Mohammed



 Khalid Sheikh Mohammed after his capture in 2003
The journalist Yosri Fouda of the Arabic television channel Al Jazeera reported that, in April 2002, Khalid Sheikh Mohammed admitted his involvement, along with Ramzi bin al-Shibh.[24][25][26] The 9/11 Commission Report determined that the animosity towards the United States felt by Mohammed, the principal architect of the 9/11 attacks, stemmed from his "violent disagreement with U.S. foreign policy favoring Israel".[27]
Mohammed was also an adviser and financier of the 1993 World Trade Center bombing and the uncle of Ramzi Yousef, the lead bomber in that attack.[28][29]
Mohammed was arrested on March 1, 2003, in Rawalpindi, Pakistan, by Pakistani security officials working with the CIA, then transported to Guantanamo Bay and interrogated using methods including waterboarding.[30][31] During U.S. hearings at Guantanamo Bay in March 2007, Mohammed again confessed his responsibility for the attacks, stating he "was responsible for the 9/11 operation from A to Z" and that his statement was not made under duress.[26][32]
Other al-Qaeda members
In "Substitution for Testimony of Khalid Sheikh Mohammed" from the trial of Zacarias Moussaoui, five people are identified as having been completely aware of the operation's details. They are bin Laden, Khalid Sheikh Mohammed, Ramzi bin al-Shibh, Abu Turab al-Urduni, and Mohammed Atef.[33] To date, only peripheral figures have been tried or convicted for the attacks.
On September 26, 2005, the Spanish high court sentenced Abu Dahdah to 27 years in prison for conspiracy on the 9/11 attacks and being a member of the terrorist organization al-Qaeda. At the same time, another 17 al-Qaeda members were sentenced to penalties of between six and eleven years.[34] On February 16, 2006, the Spanish Supreme Court reduced the Abu Dahdah penalty to 12 years because it considered that his participation in the conspiracy was not proven.[35]
Also, in 2006, Moussaoui, who some originally suspected might have been the assigned 20th hijacker, was convicted for the lesser role of conspiracy to commit acts of terrorism and air piracy. He is serving a life sentence without parole in the United States.[36][37] Mounir el-Motassadeq, an associate of the Hamburg-based hijackers, is serving 15 years in Germany for his role in helping the hijackers prepare for the attacks.[38]
The Hamburg cell in Germany included radical Islamists who eventually came to be key operatives in the 9/11 attacks.[39] Mohamed Atta, Marwan al-Shehhi, Ziad Jarrah, Ramzi bin al-Shibh, and Said Bahaji were all members of al-Qaeda's Hamburg cell.[40]
Motives
Main article: Motives for the September 11 attacks
Osama bin Laden's declaration of a holy war against the United States, and a 1998 fatwā signed by bin Laden and others, calling for the killing of American civilians,[11] are seen by investigators as evidence of his motivation.[41] In bin Laden's November 2002 "Letter to America", he explicitly stated that al-Qaeda's motives for their attacks include
Support for the "attacks against Muslims" in Somalia
Support of Russian "atrocities against Muslims" in Chechnya
Support of authoritarian regimes in the Middle East such as Egypt, Saudi Arabia and Jordan
Support of Indian "oppression against Muslims" in Kashmir
The presence of U.S. troops in Saudi Arabia[42][43]
U.S. support of Israel[44][45]
The sanctions against Iraq[46]
After the attacks, bin Laden and al-Zawahiri released additional video tapes and audio tapes, some of which repeated those reasons for the attacks. Two particularly important publications were bin Laden's 2002 "Letter to America",[47] and a 2004 video tape by bin Laden.[48]
Bin Laden interpreted the Prophet Muhammad as having banned the "permanent presence of infidels in Arabia".[49] In 1996, bin Laden issued a fatwā calling for American troops to leave Saudi Arabia. In 1998, al-Qaeda wrote, "for over seven years the United States has been occupying the lands of Islam in the holiest of places, the Arabian Peninsula, plundering its riches, dictating to its rulers, humiliating its people, terrorizing its neighbors, and turning its bases in the Peninsula into a spearhead through which to fight the neighboring Muslim peoples."[50]
In a December 1999 interview, bin Laden said he felt that Americans were "too near to Mecca", and considered this a provocation to the entire Muslim world.[51] One analysis of suicide terrorism suggested that without U.S. troops in Saudi Arabia, al-Qaeda likely would not have been able to get people to commit to suicide missions.[52]
In the 1998 fatwā, al-Qaeda identified the Iraq sanctions as a reason to kill Americans, condemning the "protracted blockade"[50] among other actions that constitute a declaration of war against "Allah, his messenger, and Muslims."[50] The fatwā declared that "the ruling to kill the Americans and their allies – civilians and military – is an individual duty for every Muslim who can do it in any country in which it is possible to do it, in order to liberate the al-Aqsa Mosque and the holy mosque of Mecca from their grip, and in order for their [the Americans'] armies to move out of all the lands of Islam, defeated and unable to threaten any Muslim."[11][53]
Bin Laden claimed, in 2004, that the idea of destroying the towers had first occurred to him in 1982, when he witnessed Israel's bombardment of high-rise apartment buildings during the 1982 Lebanon War.[54][55] Some analysts, including Mearsheimer and Walt, also claim that one motivation for the attacks was U.S. support of Israel.[45][51] In 2004 and 2010, bin Laden again connected the September 11 attacks with U.S. support of Israel, although most of the letter expressed bin Laden's disdain with President Bush and bin Laden's hope to "destroy and bankrupt" the U.S.[56][57]
In addition to those cited by bin Laden and al-Qaeda, analysts have suggested other motives, including western support of Islamist and non-Islamist authoritarian regimes in Saudi Arabia, Iran, Egypt, Iraq, Pakistan and northern Africa, and the presence of western troops in some of these countries.[58] Other authors suggest the "humiliation" resulting from the Islamic world falling behind the Western world – this discrepancy rendered especially visible by the globalization trend[59][60] and a desire to provoke the U.S. into a broader war against the Islamic world in the hope of motivating more allies to support al-Qaeda.
Others have argued that 9/11 was a strategic move with the objective of provoking America into a war that would incite a pan-Islamic revolution.[61][62]
Planning of the attacks
Main article: Planning of the September 11 attacks

ground zero and surrounding area as seen from directly above depicting where the two planes impacted the towers

 Map showing the attacks on the World Trade Center (the planes are not drawn to scale)
The idea for the attacks came from Khalid Sheikh Mohammed, who first presented it to Osama bin Laden in 1996.[63] At that time, bin Laden and al-Qaeda were in a period of transition, having just relocated back to Afghanistan from Sudan.[64] The 1998 African Embassy bombings and bin Laden's 1998 fatwā marked a turning point, as bin Laden became intent on attacking the United States.[64]
In late 1998 or early 1999, bin Laden gave approval for Mohammed to go forward with organizing the plot. A series of meetings occurred in early 1999, involving Mohammed, bin Laden, and his deputy Mohammed Atef.[64] Atef provided operational support for the plot, including target selections and helping arrange travel for the hijackers.[64] Bin Laden overruled Mohammed, rejecting some potential targets such as the U.S. Bank Tower in Los Angeles because, "there was not enough time to prepare for such an operation".[65][66]



 Diagram showing the attacks on the World Trade Center
Bin Laden provided leadership and financial support for the plot, and was involved in selecting participants.[67] Bin Laden initially selected Nawaf al-Hazmi and Khalid al-Mihdhar, both experienced jihadists who had fought in Bosnia. Hazmi and Mihdhar arrived in the United States in mid-January 2000. In spring 2000, Hazmi and Mihdhar took flying lessons in San Diego, California, but both spoke little English, did poorly with flying lessons, and eventually served as secondary – or "muscle" – hijackers.[68][69]
In late 1999, a group of men from Hamburg, Germany, arrived in Afghanistan, including Mohamed Atta, Marwan al-Shehhi, Ziad Jarrah, and Ramzi bin al-Shibh.[70] Bin Laden selected these men because they were educated, could speak English, and had experience living in the West.[71] New recruits were routinely screened for special skills and al-Qaeda leaders consequently discovered that Hani Hanjour already had a commercial pilot's license.[72]
Hanjour arrived in San Diego on December 8, 2000, joining Hazmi.[73] They soon left for Arizona, where Hanjour took refresher training. Marwan al-Shehhi arrived at the end of May 2000, while Atta arrived on June 3, 2000, and Jarrah arrived on June 27, 2000. Bin al-Shibh applied several times for a visa to the United States, but as a Yemeni, he was rejected out of concerns he would overstay his visa and remain as an illegal immigrant. Bin al-Shibh stayed in Hamburg, providing coordination between Atta and Mohammed. The three Hamburg cell members all took pilot training in South Florida.
In spring 2001, the secondary hijackers began arriving in the United States.[74] In July 2001, Atta met with bin al-Shibh in Spain, where they coordinated details of the plot, including final target selection. Bin al-Shibh also passed along bin Laden's wish for the attacks to be carried out as soon as possible.[75]
Attacks
Further information: Timeline for the day of the September 11 attacks



 Flight paths of the four planes used on September 11
Early on the morning of September 11, 2001, 19 hijackers took control of four commercial airliners (two Boeing 757 and two Boeing 767) en route to California (three headed to LAX in Los Angeles, and one to San Francisco) after takeoffs from Boston, Massachusetts; Newark, New Jersey; and Washington, D.C.[76] Large planes with long flights were selected for hijacking because they would be heavily fueled.[77]
The four flights were:
American Airlines Flight 11: Left Boston's Logan Airport at 7:59 a.m. en route to Los Angeles with a crew of 11 and 76 passengers, not including five hijackers. The hijackers flew the plane into the North Tower of the World Trade Center at 8:46 a.m.
United Airlines Flight 175: Left Logan Airport at 8:14 a.m. en route to Los Angeles with a crew of nine and 51 passengers, not including five hijackers. The hijackers flew the plane into the South Tower of the World Trade Center at 9:03 a.m.
American Airlines Flight 77: Left Washington Dulles International Airport in Virginia at 8:20 a.m. en route to Los Angeles with a crew of six and 53 passengers, not including five hijackers. The hijackers flew the plane into the Pentagon at 9:37 a.m.
United Airlines Flight 93: Left Newark International Airport at 8:42 a.m. en route to San Francisco, with a crew of seven and 33 passengers, not including four hijackers. As passengers attempted to subdue the hijackers, the aircraft crashed into the ground near Shanksville, Pennsylvania, at 10:03 a.m.
Media coverage was intense during the attacks and aftermath, beginning moments after the first crash into the World Trade Center.[78]
Events



 Plume of September 11 attack seen from space by NASA.[79]
At 8:46 a.m., five hijackers crashed American Airlines Flight 11 into the northern facade of the World Trade Center's North Tower (1 WTC), and at 9:03 a.m., another five hijackers crashed United Airlines Flight 175 into the southern facade of the South Tower (2 WTC).[80][81] Five hijackers flew American Airlines Flight 77 into the Pentagon at 9:37 a.m.[82]
A fourth flight, United Airlines Flight 93, under the control of four hijackers, crashed near Shanksville, Pennsylvania, southeast of Pittsburgh, at 10:03 a.m. after the passengers fought the hijackers. Flight 93's target is believed to have been either the Capitol or the White House.[77] Flight 93's cockpit voice recorder revealed crew and passengers tried to seize control of the plane from the hijackers after learning through phone calls that Flights 11, 77, and 175 had been crashed into buildings that morning.[83] Once it became evident to the hijackers that the passengers might regain control of the plane, the hijackers rolled the plane and intentionally crashed it.[84][85]



 The north face of Two World Trade Center (south tower) immediately after being struck by United Airlines Flight 175
Some passengers and crew members who called from the aircraft using the cabin airphone service and mobile phones provided details: several hijackers were aboard each plane; they used mace, tear gas, or pepper spray to overcome attendants; and some people aboard had been stabbed.[86][87][88][89][90][91][92] Reports indicated hijackers stabbed and killed pilots, flight attendants, and one or more passengers.[76][93] In their final report, the 9/11 Commission found the hijackers had recently purchased multi-function hand tools and assorted knives and blades.[94][95] A flight attendant on Flight 11, a passenger on Flight 175, and passengers on Flight 93 said the hijackers had bombs, but one of the passengers said he thought the bombs were fake. The FBI found no traces of explosives at the crash sites, and the 9/11 Commission concluded that the bombs were probably fake.[76]
Three buildings in the World Trade Center complex collapsed due to fire-induced structural failure.[96] The South Tower collapsed at 9:59 a.m. after burning for 56 minutes in a fire caused by the impact of United Airlines Flight 175 and the explosion of its fuel.[96] The North Tower collapsed at 10:28 a.m. after burning for 102 minutes.[96] When the North Tower collapsed, debris fell on the nearby 7 World Trade Center building (7 WTC), damaging it and starting fires. These fires burned for hours, compromising the building's structural integrity, and 7 WTC collapsed at 5:21 p.m.[97][98] The Pentagon sustained major damage.


File:Pentagon Security Camera 1.ogv
Play media


 Security camera footage of Flight 77 hitting the Pentagon.[99] The plane hits the Pentagon approximately 86 seconds after the beginning of this recording.
At 9:40 a.m., the FAA grounded all aircraft within the continental U.S., and aircraft already in flight were told to land immediately. All international civilian aircraft were either turned back or redirected to airports in Canada or Mexico, and all international flights were banned from landing on U.S. soil for three days.[100] The attacks created widespread confusion among news organizations and air traffic controllers. Among the unconfirmed and often contradictory news reports aired throughout the day, one of the most prevalent said a car bomb had been detonated at the U.S. State Department's headquarters in Washington, D.C.[101] Another jet—Delta Air Lines Flight 1989—was suspected of having been hijacked, but the aircraft responded to controllers and landed safely in Cleveland, Ohio.[102]
In a September[verification needed] 2002 interview, Khalid Sheikh Mohammed and Ramzi bin al-Shibh, who are believed to have organized the attacks, said Flight 93's intended target was the United States Capitol, not the White House.[103] During the planning stage of the attacks, Mohamed Atta, the hijacker and pilot of Flight 11, thought the White House might be too tough a target and sought an assessment from Hani Hanjour, who would later hijack and pilot Flight 77.[104] Mohammed said al-Qaeda initially planned to target nuclear installations rather than the World Trade Center and the Pentagon, but decided against it, fearing things could "get out of control".[105] Final decisions on targets, according to Mohammed, were left in the hands of the pilots.[104]
Casualties
Main articles: Casualties of the September 11 attacks and New York City Fire Department casualties of the September 11 attacks



 The remains of 6 World Trade Center, 7 World Trade Center, and 1 World Trade Center on September 17, 2001
The attacks resulted in the deaths of 2,996 people, including the 19 hijackers and 2,977 victims.[106] The victims included 246 on the four planes (from which there were no survivors), 2,606 in New York City in the towers and on the ground, and 125 at the Pentagon.[107][108] Nearly all of the victims were civilians; 55 military personnel were among those killed at the Pentagon.[109]
More than 90% of the workers and visitors who died in the towers had been at or above the points of impact.[110] In the North Tower, 1,355 people at or above the point of impact were trapped and died of smoke inhalation, fell or jumped from the tower to escape the smoke and flames, or were killed in the building's eventual collapse. The destruction of all three staircases in the tower when Flight 11 hit made it impossible for anyone above the impact zone to escape. 107 people below the point of impact died as well.[110]
In the South Tower, one stairwell (A), was left intact after Flight 175 hit, allowing 14 people located on the floors of impact (including one man who saw the plane coming at him) and four more from the floors above to escape. 911 operators who received calls from individuals inside the tower were not well informed of the situation as it rapidly unfolded and as a result, told callers not to descend the tower on their own.[111] 630 people died in that tower, fewer than half the number killed in the North Tower.[110] Casualties in the South Tower were significantly reduced by some occupants deciding to start evacuating as soon as the North Tower was struck.[112]



 Urban Search and Rescue Task Force German Shepherd dog works to uncover survivors at the site of the collapsed World Trade Center after the September 11, 2001 attacks.
At least 200 people fell or jumped to their deaths from the burning towers (as exemplified in the photograph The Falling Man), landing on the streets and rooftops of adjacent buildings hundreds of feet below.[113] Some occupants of each tower above the point of impact made their way toward the roof in hope of helicopter rescue, but the roof access doors were locked. No plan existed for helicopter rescues, and the combination of roof equipment and thick smoke and intense heat prevented helicopters from approaching.[114] A total of 411 emergency workers died as they tried to rescue people and fight fires. The New York City Fire Department (FDNY) lost 340 firefighters, a chaplain, and two paramedics.[115] The New York City Police Department (NYPD) lost 23 officers.[116] The Port Authority Police Department lost 37 officers.[117] Eight emergency medical technicians (EMTs) and paramedics from private emergency medical services units were killed.[118][119]
Cantor Fitzgerald L.P., an investment bank on the 101st–105th floors of the North Tower, lost 658 employees, considerably more than any other employer.[120] Marsh Inc., located immediately below Cantor Fitzgerald on floors 93–100, lost 358 employees,[121][122] and 175 employees of Aon Corporation were also killed.[123] The National Institute of Standards and Technology (NIST) estimated that about 17,400 civilians were in the World Trade Center complex at the time of the attacks. Turnstile counts from the Port Authority suggest 14,154 people were typically in the Twin Towers by 8:45 a.m.[124][125] The vast majority of people below the impact zone safely evacuated the buildings.[126]
After New York, New Jersey lost the most state citizens, with the city of Hoboken sustaining the most deaths.[127] More than 90 countries lost citizens in the attacks on the World Trade Center.[128] Two people were added to the official death toll after dying from health conditions linked to exposure to dust from the collapse of the World Trade Center.[129][130]
Deaths (+ hijackers)

New York City
World Trade Center 2,606[107][131]
American 11 87 + 5[132]
United 175 60 + 5[133]
Arlington
Pentagon 125[134]
American 77 59 + 5[135]
Near Shanksville
United 93 40 + 4[136]
Total
2,977 + 19
Weeks after the attack, the death toll was estimated to be over 6,000, more than twice the number of deaths eventually confirmed.[137] The city was only able to identify remains for about 1,600 of the World Trade Center victims. The medical examiner's office collected "about 10,000 unidentified bone and tissue fragments that cannot be matched to the list of the dead".[138] Bone fragments were still being found in 2006 by workers who were preparing to demolish the damaged Deutsche Bank Building. In 2010, a team of anthropologists and archaeologists searched for human remains and personal items at the Fresh Kills Landfill, where seventy-two more human remains were recovered, bringing the total found to 1,845. DNA profiling continues in an attempt to identify additional victims.[139][140][141] The remains are being held in storage in Memorial Park, outside the New York City Medical Examiner’s facilities. It is expected that the remains will be moved in 2013 to a repository behind a wall at the 9/11 museum. In July 2011, a team of scientists at the Office of Chief Medical Examiner was still trying to identify remains, in the hope that improved technology will allow them to identify other victims.[141] On September 16, 2013, the 1,638th victim was identified. There are still 1,115 victims that have not been identified.[142]
Damage
Further information: Lost artworks § Works destroyed in the September 11 attacks



 World Trade Center site (Ground Zero) with an overlay showing the original building locations.


 The Pentagon was damaged by fire and partly collapsed.
Along with the 110-floor Twin Towers, numerous other buildings at the World Trade Center site were destroyed or badly damaged, including WTC buildings 3 through 7 and St. Nicholas Greek Orthodox Church.[143] The North Tower, South Tower, the Marriott Hotel (3 WTC), and 7 WTC were completely destroyed. The U.S. Customs House (6 World Trade Center), 4 World Trade Center, 5 World Trade Center, and both pedestrian bridges connecting buildings were severely damaged. The Deutsche Bank Building on 130 Liberty Street was partially damaged and demolished some years later, starting in 2007.[144][145] The two buildings of the World Financial Center also suffered damage.[144]
The Deutsche Bank Building across Liberty Street from the World Trade Center complex was later condemned as being uninhabitable because of toxic conditions inside the office tower, and was deconstructed.[146][147] The Borough of Manhattan Community College's Fiterman Hall at 30 West Broadway was condemned due to extensive damage in the attacks, and is being rebuilt.[148] Other neighboring buildings including 90 West Street and the Verizon Building suffered major damage but have been restored.[149] World Financial Center buildings, One Liberty Plaza, the Millenium Hilton, and 90 Church Street had moderate damage and have since been restored.[150] Communications equipment on top of the North Tower was also destroyed, but media stations were quickly able to reroute signals and resume broadcasts.[143][151]
The Pentagon was severely damaged by the impact of American Airlines Flight 77 and ensuing fires, causing one section of the building to collapse.[152] As it approached the Pentagon, the airplane's wings knocked over light poles and its right engine smashed into a power generator before crashing into the western side of the building, killing all 53 passengers, 5 hijackers, and 6 crew.[153][154] The plane hit the Pentagon at the first-floor level. The front part of the fuselage disintegrated on impact, while the mid and tail sections kept moving for another fraction of a second.[155] Debris from the tail section penetrated furthest into the building, breaking through 310 feet (94 m) of the three outermost of the building's five rings.[155][156]
Rescue efforts
Main article: Rescue and recovery effort after the September 11 attacks

An injured victim is being loaded into a paramedic van with the burning Pentagon in the background

 An injured victim of the Pentagon attack is evacuated.
The New York City Fire Department deployed 200 units (half of the department) to the site. Their efforts were supplemented by numerous off-duty firefighters and emergency medical technicians.[157][158][159] The New York City Police Department sent Emergency Service Units and other police personnel, and deployed its aviation unit. Once on the scene, the FDNY, NYPD, and Port Authority police did not coordinate efforts and performed redundant searches for civilians.[157][160] As conditions deteriorated, the NYPD aviation unit relayed information to police commanders, who issued orders for its personnel to evacuate the towers; most NYPD officers were able to safely evacuate before the buildings collapsed.[160][161] With separate command posts set up and incompatible radio communications between the agencies, warnings were not passed along to FDNY commanders.
After the first tower collapsed, FDNY commanders issued evacuation warnings; however, due to technical difficulties with malfunctioning radio repeater systems, many firefighters never heard the evacuation orders. 9-1-1 dispatchers also received information from callers that was not passed along to commanders on the scene.[158] Within hours of the attack, a substantial search and rescue operation was launched. After months of around-the-clock operations, the World Trade Center site was cleared by the end of May 2002.[162]
Aftermath
Immediate response

Three high-level politicians and a General, all displaying grim facial expressions, flank the main speaker.

 Eight hours after the attacks, Donald Rumsfeld, then U.S. Secretary of Defense, declares "The Pentagon is functioning."
Further information: Airport security repercussions due to the September 11 attacks, Closings and cancellations following the September 11 attacks, Aftermath of the September 11 attacks, Reactions to the September 11 attacks, U.S. government response to the September 11 attacks and U.S. military response during the September 11 attacks
At 8:32 a.m., Federal Aviation Administration (FAA) officials were notified Flight 11 had been hijacked and they in turn notified the North American Aerospace Defense Command (NORAD). NORAD scrambled two F-15s from Otis Air National Guard Base in Massachusetts and they were airborne by 8:53 a.m.[163] Because of slow and confused communication from FAA officials, NORAD had 9 minutes' notice that Flight 11 had been hijacked, and no notice about any of the other flights before they crashed.[163] After both of the Twin Towers had already been hit, more fighters were scrambled from Langley Air Force Base in Virginia at 9:30 a.m.[163] At 10:20 a.m. Vice President Dick Cheney issued orders to shoot down any commercial aircraft that could be positively identified as being hijacked. However, these instructions were not relayed in time for the fighters to take action.[163][164][165][166] Some fighters took to the air without live ammunition, knowing that to prevent the hijackers from striking their intended targets, the pilots might have to intercept and crash their fighters into the hijacked planes, possibly ejecting at the last moment.[167]
For the first time in U.S. history, SCATANA was invoked, closing all airspace and immediately grounding all non-emergency civilian aircraft in the United States, Canada, and several other countries,[168] thus stranding tens of thousands of passengers across the world.[169] The Federal Aviation Administration closed American airspace to all international flights, causing about five hundred flights to be turned back or redirected to other countries. Canada received 226 of the diverted flights and launched Operation Yellow Ribbon to deal with the large numbers of grounded planes and stranded passengers.[170]
The 9/11 attacks had immediate effects upon the American people.[171] Police and rescue workers from around the country took leaves of absence, traveling to New York City to help recover bodies from the twisted remnants of the Twin Towers.[172] Blood donations across the U.S. surged in the weeks after 9/11.[173][174]
The deaths of adults who were killed in the attacks or died in rescue operations resulted in over 3,000 children losing a parent.[175] Subsequent studies documented children's reactions to these actual losses and to feared losses of life, the protective environment in the aftermath of the attacks, and effects on surviving caregivers.[176][177][178]
Domestic reactions













At a joint session of Congress, President Bush pledges to defend America's freedom against the fear of terrorism, September 20, 2001 (audio only).
Following the attacks, President Bush's approval rating soared to 90%.[179] On September 20, 2001, he addressed the nation and a joint session of the United States Congress regarding the events of September 11 and the subsequent nine days of rescue and recovery efforts, and described his intended response to the attacks. New York City mayor Rudy Giuliani's highly visible role won him high praise in New York and nationally.[180]
Many relief funds were immediately set up to assist victims of the attacks, with the task of providing financial assistance to the survivors of the attacks and to the families of victims. By the deadline for victim's compensation on September 11, 2003, 2,833 applications had been received from the families of those who were killed.[181]




Statement by President Bush in his Address to the Nation







George W. Bush's address to the people of the United States, September 11, 2001, 8:30 pm EDT.

Problems playing this file? See media help.
Contingency plans for the continuity of government and the evacuation of leaders were implemented almost immediately after the attacks.[169] However, Congress was not told that the United States had been under a continuity of government status until February 2002.[182]
In the largest restructuring of the U.S. government in contemporary history, the United States enacted the Homeland Security Act of 2002, creating the Department of Homeland Security. Congress also passed the USA PATRIOT Act, saying it would help detect and prosecute terrorism and other crimes.[183] Civil liberties groups have criticized the PATRIOT Act, saying it allows law enforcement to invade the privacy of citizens and that it eliminates judicial oversight of law enforcement and domestic intelligence.[184][185][186] In an effort to effectively combat future acts of terrorism, the National Security Agency (NSA) was given broad powers. NSA commenced warrantless surveillance of telecommunications which was sometimes criticized since it permitted the agency "to eavesdrop on telephone and e-mail communications between the United States and people overseas without a warrant".[187] In response to requests by various intelligence agencies, the United States Foreign Intelligence Surveillance Court permitted an expansion of powers by the US Government in seeking, obtaining, and sharing information on US citizens as well as non-US people from around the world.[188]
Hate crimes
Numerous incidents of harassment and hate crimes against Muslims and South Asians were reported in the days following the 9/11 attacks.[189][190][191] Sikhs were also targeted because Sikh males usually wear turbans, which are stereotypically associated with Muslims. There were reports of attacks on mosques and other religious buildings (including the firebombing of a Hindu temple), and assaults on people, including one murder: Balbir Singh Sodhi, a Sikh mistaken for a Muslim, was fatally shot on September 15, 2001, in Mesa, Arizona.[191]
According to an academic study, people perceived to be Middle Eastern were as likely to be victims of hate crimes as followers of Islam during this time. The study also found a similar increase in hate crimes against people who may have been perceived as Muslims, Arabs, and others thought to be of Middle Eastern origin.[192] A report by the South Asian American advocacy group known as South Asian Americans Leading Together, documented media coverage of 645 bias incidents against Americans of South Asian or Middle Eastern descent between September 11 and 17. Various crimes such as vandalism, arson, assault, shootings, harassment, and threats in numerous places were documented.[193][194]
Muslim American response
Muslim organizations in the United States were swift to condemn the attacks and called "upon Muslim Americans to come forward with their skills and resources to help alleviate the sufferings of the affected people and their families".[195] These organizations included the Islamic Society of North America, American Muslim Alliance, American Muslim Council, Council on American-Islamic Relations, Islamic Circle of North America, and the Shari'a Scholars Association of North America. Along with monetary donations, many Islamic organizations launched blood drives and provided medical assistance, food, and shelter for victims.[196][197][198]
International reactions
Main article: Reactions to the September 11 attacks



Vladimir Putin and his wife attending a commemoration service for the victims of the September 11 attacks, November 16, 2001
The attacks were denounced by mass media and governments worldwide. Across the globe, nations offered pro-American support and solidarity.[199] Leaders in most Middle Eastern countries, and Afghanistan, condemned the attacks. Iraq was a notable exception, with an immediate official statement that, "the American cowboys are reaping the fruit of their crimes against humanity".[200] While the government of Saudi Arabia officially condemned the attacks, privately many Saudis favored bin Laden's cause.[201][202] As in the United States, the aftermath of the attacks saw tensions increase in other countries between Muslims and non-Muslims.[203]
United Nations Security Council Resolution 1368 condemned the attacks, and expressed readiness to take all necessary steps to respond and combat all forms of terrorism in accordance with their Charter.[204] Numerous countries introduced anti-terrorism legislation and froze bank accounts they suspected of al-Qaeda ties.[205][206] Law enforcement and intelligence agencies in a number of countries arrested alleged terrorists.[207][208]
British Prime Minister Tony Blair said Britain stood "shoulder to shoulder" with the United States.[209] A few days later, Blair flew to Washington to affirm British solidarity with the United States. In a speech to Congress, nine days after the attacks, which Blair attended as a guest, President Bush declared "America has no truer friend than Great Britain."[210] Subsequently, Prime Minister Blair embarked on two months of diplomacy to rally international support for military action; he held 54 meetings with world leaders and travelled more than 40,000 miles (60,000 km).[211]
Tens of thousands of people attempted to flee Afghanistan following the attacks, fearing a response by the United States. Pakistan, already home to many Afghan refugees from previous conflicts, closed its border with Afghanistan on September 17, 2001. Approximately one month after the attacks, the United States led a broad coalition of international forces to overthrow the Taliban regime from Afghanistan for their harboring of al-Qaeda.[212] Though Pakistani authorities were initially reluctant to align themselves with the United States against the Taliban, they permitted the coalition access to their military bases, and arrested and handed over to the U.S. over 600 suspected al-Qaeda members.[213][214]
The U.S. set up the Guantanamo Bay detention camp to hold inmates they defined as "illegal enemy combatants". The legitimacy of these detentions has been questioned by the European Union and human rights organizations.[215][216][217]
Military operations
See also: War on Terror
At 2:40 p.m. in the afternoon of September 11, Secretary of Defense Donald Rumsfeld was issuing rapid orders to his aides to look for evidence of Iraqi involvement. According to notes taken by senior policy official Stephen Cambone, Rumsfeld asked for, "Best info fast. Judge whether good enough hit S.H." (Saddam Hussein) "at same time. Not only UBL" (Osama bin Laden).[218] Cambone's notes quoted Rumsfeld as saying, "Need to move swiftly – Near term target needs – go massive – sweep it all up. Things related and not."[219][220]

A line of soldiers carrying equipment on their backs walking toward a transport helicopter in desert terrain

U.S. soldiers in Afghanistan
The NATO council declared the attacks on the United States were an attack on all NATO nations which satisfied Article 5 of the NATO charter. This marked the first invocation of Article 5, which had been written during the Cold War with an attack by the Soviet Union in mind.[221] Australian Prime Minister John Howard who was in Washington D.C. during the attacks invoked Article IV of the ANZUS treaty.[222] The Bush administration announced a War on Terror, with the stated goals of bringing bin Laden and al-Qaeda to justice and preventing the emergence of other terrorist networks. These goals would be accomplished by imposing economic and military sanctions against states harboring terrorists, and increasing global surveillance and intelligence sharing.
On September 14, 2001, the U.S. Congress passed the Authorization for Use of Military Force Against Terrorists. Still in effect, it grants the President the authority to use all "necessary and appropriate force" against those whom he determined "planned, authorized, committed or aided" the September 11th attacks, or who harbored said persons or groups.
On October 7, 2001, the War in Afghanistan began when U.S. and British forces initiated aerial bombing campaigns targeting Taliban and al-Qaeda camps, then later invaded Afghanistan with ground troops of the Special Forces. The overthrow of the Taliban rule of Afghanistan by a U.S.-led coalition was the second-biggest operation of the U.S. Global War on Terrorism outside of the United States, and the largest directly connected to terrorism. Conflict in Afghanistan between the Taliban insurgency and the International Security Assistance Force is ongoing. The Philippines and Indonesia, among other nations with their own internal conflicts with Islamic terrorism, also increased their military readiness.[223][224]
Effects
Health issues
Main article: Health effects arising from the September 11 attacks



 Survivors were covered in dust after the collapse of the towers.
Hundreds of thousands of tons of toxic debris containing more than 2,500 contaminants, including known carcinogens, were spread across Lower Manhattan due to the collapse of the Twin Towers.[225][226] Exposure to the toxins in the debris is alleged to have contributed to fatal or debilitating illnesses among people who were at ground zero.[227][228] The Bush administration ordered the Environmental Protection Agency (EPA) to issue reassuring statements regarding air quality in the aftermath of the attacks, citing national security, but the EPA did not determine that air quality had returned to pre-September 11 levels until June 2002.[229]
Health effects extended to residents, students, and office workers of Lower Manhattan and nearby Chinatown.[230] Several deaths have been linked to the toxic dust, and the victims' names were included in the World Trade Center memorial.[231] Approximately 18,000 people have been estimated to have developed illnesses as a result of the toxic dust.[232] There is also scientific speculation that exposure to various toxic products in the air may have negative effects on fetal development. A notable children's environmental health center is currently analyzing the children whose mothers were pregnant during the WTC collapse, and were living or working nearby.[233] A study of rescue workers released in April 2010 found that all those studied had impaired lung functions, and that 30–40% were reporting little or no improvement in persistent symptoms that started within the first year of the attack.[234]
Years after the attacks, legal disputes over the costs of illnesses related to the attacks were still in the court system. On October 17, 2006, a federal judge rejected New York City's refusal to pay for health costs for rescue workers, allowing for the possibility of numerous suits against the city.[235] Government officials have been faulted for urging the public to return to lower Manhattan in the weeks shortly after the attacks. Christine Todd Whitman, administrator of the EPA in the aftermath of the attacks, was heavily criticized by a U.S. District Judge for incorrectly saying that the area was environmentally safe.[236] Mayor Giuliani was criticized for urging financial industry personnel to return quickly to the greater Wall Street area.[237]
The United States Congress passed the James L. Zadroga 9/11 Health and Compensation Act on December 22, 2010, and President Barack Obama signed the act into law on January 2, 2011. It allocated $4.2 billion to create the World Trade Center Health Program, which provides testing and treatment for people suffering from long-term health problems related to the 9/11 attacks.[238][239] The WTC Health Program replaced preexisting 9/11-related health programs such as the Medical Monitoring and Treatment Program and the WTC Environmental Health Center program.[239]
Weather
The average diurnal temperature range throughout the United States increased markedly in the three days following the attacks. Some research suggests that the absence of contrails caused by the grounding of all planes in the United States immediately thereafter was responsible for some of this increase.[240]
Economic



 The 9/11 attacks had a major effect on the economy of New York City.
Main article: Economic effects arising from the September 11 attacks
The attacks had a significant economic impact on United States and world markets.[241] The stock exchanges did not open on September 11 and remained closed until September 17. Reopening, the Dow Jones Industrial Average (DJIA) fell 684 points, or 7.1%, to 8921, a record-setting one-day point decline.[242] By the end of the week, the DJIA had fallen 1,369.7 points (14.3%), at the time its largest one-week point drop in history.[243] In 2001 dollars, U.S. stocks lost $1.4 trillion in valuation for the week.[243]
In New York City, about 430,000 job-months and $2.8 billion dollars in wages were lost in the three months after the attacks. The economic effects were mainly on the economy's export sectors.[244] The city's GDP was estimated to have declined by $27.3 billion for the last three months of 2001 and all of 2002. The U.S. government provided $11.2 billion in immediate assistance to the Government of New York City in September 2001, and $10.5 billion in early 2002 for economic development and infrastructure needs.[245] Also hurt were small businesses in Lower Manhattan near the World Trade Center, 18,000 of which were destroyed or displaced, resulting in lost jobs and their consequent wages. Assistance was provided by Small Business Administration loans, federal government Community Development Block Grants, and Economic Injury Disaster Loans.[245] Some 31,900,000 square feet (2,960,000 m2) of Lower Manhattan office space was damaged or destroyed.[246] Many wondered whether these jobs would return, and if the damaged tax base would recover.[247] Studies of the economic effects of 9/11 show the Manhattan office real-estate market and office employment were less affected than first feared, because of the financial services industry's need for face-to-face interaction.[248][249]
North American air space was closed for several days after the attacks and air travel decreased upon its reopening, leading to a nearly 20% cutback in air travel capacity, and exacerbating financial problems in the struggling U.S. airline industry.[250]
The September 11 attacks also indirectly led to the U.S. wars in Afghanistan and Iraq,[251] as well as additional homeland security spending, totaling at least $5 trillion.[252]

Cultural
Further information: List of cultural references to the September 11 attacks and List of entertainment affected by the September 11 attacks
The impact of 9/11 extends beyond geopolitics into society and culture in general. Immediate responses to 9/11 included greater focus on home life and time spent with family, higher church attendance, and increased expressions of patriotism such as the flying of flags.[253] The radio industry responded by removing certain songs from playlists, and the attacks have subsequently been used as background, narrative or thematic elements in film, television, music and literature. Already-running television shows as well as programs developed after 9/11 have reflected post-9/11 cultural concerns.[254] 9/11 conspiracy theories have become social phenomena, despite negligible support for such views from expert scientists, engineers, and historians.[255] 9/11 has also had a major impact on the religious faith of many individuals; for some it strengthened, to find consolation to cope with the loss of loved ones and overcome their grief; others started to question their faith or lost it entirely, because they couldn't reconcile it with their view of religion.[256][257]
The culture of America succeeding the attacks is noted for heightened security and an increased demand thereof, as well as paranoia and anxiety regarding future terrorist attacks that includes most of the nation. Psychologists have also confirmed that there has been an increased amount of national anxiety in commercial air travel.[258]
Government policies toward terrorism
As a result of the attacks, many governments across the world passed legislation to combat terrorism.[259] In Germany, where several of the 9/11 terrorists had resided and taken advantage of that country's liberal asylum policies, two major anti-terrorism packages were enacted. The first removed legal loopholes that permitted terrorists to live and raise money in Germany. The second addressed the effectiveness and communication of intelligence and law enforcement.[260] Canada passed the Canadian Anti-Terrorism Act, that nation's first anti-terrorism law.[261] The United Kingdom passed the Anti-terrorism, Crime and Security Act 2001 and the Prevention of Terrorism Act 2005.[262][263] New Zealand enacted the Terrorism Suppression Act 2002.[264]
In the United States, the Department of Homeland Security was created to coordinate domestic anti-terrorism efforts. The USA Patriot Act gave the federal government greater powers, including the authority to detain foreign terror suspects for a week without charge, to monitor telephone communications, e-mail, and Internet use by terror suspects, and to prosecute suspected terrorists without time restrictions. The Federal Aviation Administration ordered that airplane cockpits be reinforced to prevent terrorists gaining control of planes, and assigned sky marshals to flights. Further, the Aviation and Transportation Security Act made the federal government, rather than airports, responsible for airport security. The law created a federal security force to inspect passengers and luggage, causing long delays and concern over passenger privacy.[265]
Investigations
FBI

A head shot of a man in his thirties looking expressionless toward the camera

Mohamed Atta, an Egyptian national, was the ringleader of the hijackers.
Immediately after the attacks, the Federal Bureau of Investigation started PENTTBOM, the largest criminal inquiry in the history of the United States. At its height, more than half of the FBI's agents worked on the investigation and followed a half-million leads.[266] The FBI concluded that there was "clear and irrefutable" evidence linking al-Qaeda and bin Laden to the attacks.[267] The FBI was quickly able to identify the hijackers, including leader Mohamed Atta, when his luggage was discovered at Boston's Logan Airport. Atta had been forced to check two of his three bags due to space limitations on the 19-seat commuter flight he took to Boston.[268] Due to a new policy instituted to prevent flight delays, the luggage failed to make it aboard American Airlines Flight 11 as planned. The luggage contained the hijackers' names, assignments and al-Qaeda connections. "It had all these Arab-language (sic) papers that amounted to the Rosetta stone of the investigation", said one FBI agent.[269]
Within hours of the attacks, the FBI released the names and in many cases the personal details of the suspected pilots and hijackers.[270][271] By midday, the U.S. National Security Agency and German intelligence agencies had intercepted communications pointing to Osama bin Laden.[272][273] On September 27, 2001, the FBI released photos of the 19 hijackers, along with information about possible nationalities and aliases.[274] Fifteen of the men were from Saudi Arabia, two from the United Arab Emirates, one (Atta) from Egypt, and one from Lebanon.[275]
Origins of the 19 hijackers

Nationality
Number

Saudi Arabia

15
United Arab Emirates

2
Egypt

1
Lebanon

1
CIA
The Inspector General of the Central Intelligence Agency (CIA) conducted an internal review of the agency's pre-9/11 performance and was harshly critical of senior CIA officials for not doing everything possible to confront terrorism. He criticized their failure to stop two of the 9/11 hijackers, Nawaf al-Hazmi and Khalid al-Mihdhar, as they entered the United States and their failure to share information on the two men with the FBI.[276] In May 2007, senators from both major U.S. political parties drafted legislation to make the review public. One of the backers, Senator Ron Wyden said, "The American people have a right to know what the Central Intelligence Agency was doing in those critical months before 9/11."[277]
9/11 Commission
Main articles: 9/11 Commission and 9/11 Commission Report
The National Commission on Terrorist Attacks Upon the United States (9/11 Commission), chaired by Thomas Kean and Lee H. Hamilton, was formed in late 2002 to prepare a thorough account of the circumstances surrounding the attacks, including preparedness for and the immediate response to the attacks.[278] On July 22, 2004, the Commission issued the 9/11 Commission Report. The report detailed the events of 9/11, found the attacks were carried out by members of al-Qaeda, and examined how security and intelligence agencies were inadequately coordinated to prevent the attacks. Formed from an independent bipartisan group of mostly former Senators, Representatives, and Governors, the commissioners explained, "We believe the 9/11 attacks revealed four kinds of failures: in imagination, policy, capabilities, and management".[279] The Commission made numerous recommendations on how to prevent future attacks, and in 2011 was dismayed that several of its recommendations had yet to be implemented.[280]
Main article: Criticism of the 9/11 Commission
After the report was issued, Hamilton and Kean wrote a book, Without Precedent: The Inside Story of the 9/11 Commission, that said the Commission was "set up to fail". Hamilton cited a short deadline, small budget, widespread political resistance, deception from government agencies, and denial of access to documents and witnesses.[281] Critics of the Commission's findings cite conflicts of interest among its members, actions taken by the CIA to impede the investigation and other misinformation provided by federal agencies, the use of unreliable evidence, a limited scope, and the redaction of a 28-page section from the final report.
Collapse of the World Trade Center
Main articles: Collapse of the World Trade Center and 7 World Trade Center § 9/11 and collapse



 The exterior support columns from the lower level of the south tower remained standing after the building collapsed.
The U.S. National Institute of Standards and Technology (NIST) investigated the collapses of the Twin Towers and 7 WTC. The investigations examined why the buildings collapsed and what fire protection measures were in place, and evaluated how fire protection systems might be improved in future construction.[282] The investigation into the collapse of 1 WTC and 2 WTC was concluded in October 2005 and that of 7 WTC was completed in August 2008.[283]
NIST found that the fireproofing on the Twin Towers' steel infrastructures was blown off by the initial impact of the planes and that, had this not occurred, the towers likely would have remained standing.[284] A 2007 study of the north tower's collapse published by researchers of Purdue University determined that, since the plane's impact had stripped off much of the structure's thermal insulation, the heat from a typical office fire would have softened and weakened the exposed girders and columns enough to initiate the collapse regardless of the number of columns cut or damaged by the impact.[285][286]
The director of the original investigation stated that, "the towers really did amazingly well. The terrorist aircraft didn’t bring the buildings down; it was the fire which followed. It was proven that you could take out two thirds of the columns in a tower and the building would still stand."[287] The fires weakened the trusses supporting the floors, making the floors sag. The sagging floors pulled on the exterior steel columns causing the exterior columns to bow inward. With the damage to the core columns, the buckling exterior columns could no longer support the buildings, causing them to collapse. Additionally, the report found the towers' stairwells were not adequately reinforced to provide adequate emergency escape for people above the impact zones.[288] NIST concluded that uncontrolled fires in 7 WTC caused floor beams and girders to heat and subsequently "caused a critical support column to fail, initiating a fire-induced progressive collapse that brought the building down".[283]
Reconstruction



 Rebuilt One World Trade Center nearing completion in July 2013
Further information: World Trade Center site and One World Trade Center
On the day of the attacks, New York City mayor Rudy Giuliani proclaimed, "We will rebuild. We're going to come out of this stronger than before, politically stronger, economically stronger. The skyline will be made whole again."[289]
The damaged section of the Pentagon was rebuilt and occupied within a year of the attacks.[290] The temporary World Trade Center PATH station opened in late 2003 and construction of the new 7 World Trade Center was completed in 2006. Work on rebuilding the main World Trade Center site was delayed until late 2006 when leaseholder Larry Silverstein and the Port Authority of New York and New Jersey agreed on financing.[291] One World Trade Center is currently under construction at the site and on May 20, 2013, One World Trade Center became the tallest building in the Western Hemisphere at 1,776 ft (541 m) with the installation of the spire that rests atop the building.[292]
On the World Trade Center site, three more office towers are expected to be built one block east of where the original towers stood. Construction has begun on all three of these towers; they are expected to be completed after One World Trade Center.[293]

Memorials



 The Tribute in Light on September 11, 2011, on the tenth anniversary of the attacks, seen from New Jersey. The building lit up in red, white, and blue is the new One World Trade Center under construction.
Main article: Memorials and services for the September 11 attacks
In the days immediately following the attacks, many memorials and vigils were held around the world. In addition, people posted photographs of the dead and missing all around Ground Zero. A witness described being unable to "get away from faces of innocent victims who were killed. Their pictures are everywhere, on phone booths, street lights, walls of subway stations. Everything reminded me of a huge funeral, people quiet and sad, but also very nice. Before, New York gave me a cold feeling; now people were reaching out to help each other.”[294]
One of the first memorials was the Tribute in Light, an installation of 88 searchlights at the footprints of the World Trade Center towers.[295] In New York, the World Trade Center Site Memorial Competition was held to design an appropriate memorial on the site.[296] The winning design, Reflecting Absence, was selected in August 2006, and consists of a pair of reflecting pools in the footprints of the towers, surrounded by a list of the victims' names in an underground memorial space.[297] Plans for a museum on the site have been put on hold, following the abandonment of the International Freedom Center in reaction to complaints from the families of many victims.[298]
The Pentagon Memorial was completed and opened to the public on the seventh anniversary of the attacks in 2008.[299][300] It consists of a landscaped park with 184 benches facing the Pentagon.[301] When the Pentagon was repaired in 2001–2002, a private chapel and indoor memorial were included, located at the spot where Flight 77 crashed into the building.[302]
In Shanksville, a permanent Flight 93 National Memorial is planned to include a sculpted grove of trees forming a circle around the crash site, bisected by the plane's path, while wind chimes will bear the names of the victims.[303] A temporary memorial is located 500 yards (457 m) from the crash site.[304] New York City firefighters donated a cross made of steel from the World Trade Center and mounted on top of a platform shaped like the Pentagon.[305] It was installed outside the firehouse on August 25, 2008.[306] Many other permanent memorials are elsewhere. Scholarships and charities have been established by the victims' families, and by many other organizations and private figures.[307]
On every anniversary, in New York City, the names of the victims who died there are read out against a background of somber music. The President of the United States attends a memorial service at the Pentagon,[308] and asks Americans to observe Patriot Day with a moment of silence. Smaller services are held in Shanksville, Pennsylvania, which are usually attended by the President's spouse.

See also
Book icon Book: September 11 attacks

Federal Express Flight 705 – 1994 cockpit attack
Southwest Airlines Flight 1763 – August 2000 cockpit attack
Bojinka plot – plot by Ramzi Yousef and Khalid Shaikh Mohammed, foiled in 1995, to attack multiple airliners and crash a plane into the CIA headquarters


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Citations
Notes
1.Jump up ^ 9/11 is pronounced "nine eleven". The slash is not part of the pronunciation. The name is frequently used in British English as well as American English although the dating conventions differ.
References
1.^ Jump up to: a b c "Bin Laden claims responsibility for 9/11". CBC News. October 29, 2004. Retrieved September 1, 2011. "Al-Qaeda leader Osama bin Laden appeared in a new message aired on an Arabic TV station Friday night, for the first time claiming direct responsibility for the 2001 attacks against the United States."
2.Jump up ^ "How much did the September 11 terrorist attack cost America?". 2004. Institute for the Analysis of Global Security. Retrieved April 30, 2014.
3.Jump up ^ Inside 9/11: Zero Hour, National Geographic Channel documentary, 2005.
4.Jump up ^ "Deadliest Days in Law Enforcement History". National Law Enforcement Officers Memorial Fund. Retrieved April 9, 2014.
5.Jump up ^ Congress. Congressional Record, Vol. 148, Pt. 7, May 23, 2002 to June 12, 2002. Government Printing Office. p. 9909. Retrieved April 9, 2014.
6.Jump up ^ "1 World Trade Center (Freedom Tower)". Lower Manhattan Development Corporation. Retrieved September 11, 2013.
7.Jump up ^ One World Trade Center
8.Jump up ^ "Al-Qaeda's origins and links". BBC News. July 20, 2004. Retrieved September 3, 2011.
9.Jump up ^ Gunaratna (2002), pp. 23–33.
10.Jump up ^ "Bin Laden's fatwā (1996)". PBS. Archived from the original on 2001-10-31. Retrieved May 29, 2014.
11.^ Jump up to: a b c d "Al Qaeda's Second Fatwa". PBS NewsHour. Public Broadcasting Service. Archived from the original on 2013-11-28. Retrieved May 29, 2014.
12.Jump up ^ "Pakistan inquiry orders Bin Laden family to remain". BBC. July 6, 2011. Retrieved September 3, 2011.
13.^ Jump up to: a b "Full transcript of bin Ladin's speech". Al Jazeera. November 2, 2004. Archived from the original on 2007-04-10. Retrieved September 3, 2011.
14.Jump up ^ "Pakistan to Demand Taliban Give Up Bin Laden as Iran Seals Afghan Border". Fox News Channel. September 16, 2001. Retrieved September 3, 2011.
15.Jump up ^ "Bin Laden on tape: Attacks 'benefited Islam greatly'". CNN. December 14, 2001. Archived from the original on 2007-12-27. Retrieved November 24, 2013. "Reveling in the details of the fatal attacks, bin Laden brags in Arabic that he knew about them beforehand and says the destruction went beyond his hopes. He says the attacks "benefited Islam greatly"."
16.Jump up ^ "Transcript: Bin Laden video excerpts". BBC News. December 27, 2001. Retrieved September 3, 2011.
17.Jump up ^ Michael, Maggie (October 29, 2004). "Bin Laden, in statement to U.S. people, says he ordered Sept. 11 attacks". SignOnSanDiego.com. Associated Press. Retrieved September 3, 2011.
18.Jump up ^ "Al-Jazeera: Bin Laden tape obtained in Pakistan". MSNBC. October 30, 2004. Retrieved September 3, 2011.
19.Jump up ^ "Bin Laden 9/11 planning video aired". CBC News. September 7, 2006. Archived from the original on 2007-10-13. Retrieved September 3, 2011.
20.Jump up ^ Clewley, Robin (September 27, 2001). "How Osama Cracked FBI's Top 10". Wired. Archived from the original on 2008-05-26. Retrieved May 29, 2014.
21.Jump up ^ "USAMA BIN LADEN". FBI Ten Most Wanted Fugitive. Federal Bureau of Investigation. Retrieved September 10, 2011.
22.Jump up ^ Baker, Peter; Cooper, Helene (May 1, 2011). "Bin Laden Is Dead, President Obama Says". New York Times. Retrieved September 3, 2011.
23.Jump up ^ Cooper, Helene (May 1, 2011). "Obama Announces Killing of Osama bin Laden". New York Times. Retrieved September 3, 2011.
24.Jump up ^ "'We left out nuclear targets, for now'". The Guardian (London). March 4, 2003. Archived from the original on 2008-03-02. Retrieved September 3, 2011. "Yosri Fouda of the Arabic television channel al-Jazeera is the only journalist to have interviewed Khalid Sheikh Mohammed, the al-Qaeda military commander arrested at the weekend. Here he describes the two-day encounter with him and his fellow organiser of September 11, Ramzi bin al- Shibh: [...] Summoning every thread of experience and courage, I looked Khalid in the eye and asked: ‘Did you do it?’ The reference to September 11 was implicit. Khalid responded with little fanfare: ‘I am the head of the al-Qaeda military committee,’ he began, ‘and Ramzi is the coordinator of the Holy Tuesday operation. And yes, we did it.’"
25.Jump up ^ Leonard, Tom; Spillius, Alex (October 10, 2008). "Alleged 9/11 mastermind wants to confess to plot". London: Telegraph. Retrieved September 3, 2011.
26.^ Jump up to: a b "September 11 suspect 'confesses'". Al Jazeera. March 15, 2007. Retrieved September 3, 2011.
27.Jump up ^ 9/11 Commission Report (2004), p. 147.
28.Jump up ^ "White House power grabs". The Washington Times. August 26, 2009. Retrieved September 3, 2011.
29.Jump up ^ Van Voris, Bob; Hurtado, Patricia (April 4, 2011). "Khalid Sheikh Mohammed Terror Indictment Unsealed, Dismissed". BusinessWeek. Retrieved September 3, 2011.
30.Jump up ^ Shannon, Elaine; Weisskopf, Michael (March 24, 2003). "Khalid Sheikh Mohammed Names Names". TIME. Retrieved September 3, 2011.
31.Jump up ^ Nichols, Michelle (May 8, 2008). "US judge orders CIA to turn over 'torture' memo-ACLU". Reuters. Retrieved September 3, 2011.
32.Jump up ^ "Key 9/11 suspect 'admits guilt'". BBC News. March 15, 2007. Retrieved April 10, 2012.
33.Jump up ^ "Substitution for Testimony of Khalid Sheikh Mohammed" (PDF). United States District Court for the Eastern District of Virginia. United States Department of Justice. 2006. p. 24. Retrieved September 3, 2011.
34.Jump up ^ "Spain jails 18 al-Qaeda operatives". The Age (Melbourne). September 27, 2005. Retrieved September 3, 2011.
35.Jump up ^ Naughton, Philippe (June 1, 2006). "Spanish court quashes 9/11 conviction". The Times. Retrieved September 3, 2011.
36.Jump up ^ Summers and Swan (2011), p. 489n.
37.Jump up ^ Youssef, Maamoun (May 24, 2006). "Bin Laden: Moussaoui Not Linked to 9/11". Washington Post. Associated Press.
38.Jump up ^ Summers and Swan (2011), p. 542n.
39.Jump up ^ "The Hamburg connection". BBC News. August 19, 2005.
40.Jump up ^ "Chapter of the 9/11 Commission Report detailing the history of the Hamburg Cell". 9/11 Commission.
41.Jump up ^ Gunarathna, pp. 61–62.
42.Jump up ^ Plotz, David (2001) What Does Osama Bin Laden Want?, Slate
43.Jump up ^ Plotz, David (2001) What Does Osama Bin Laden Want?, Slate
Bergen (2001), p. 3.
Yusufzai, Rahimullah (September 26, 2001). "Face to face with Osama". The Guardian (London). Archived from the original on 2008-01-19. Retrieved September 3, 2011.
"US pulls out of Saudi Arabia". BBC News. April 29, 2003. Retrieved September 3, 2011.
"Saga of Dr. Zawahri Sheds Light On the Roots of al Qaeda Terror". Wall Street Journal. July 2, 2002. Retrieved September 3, 2011.
"Tenth Public Hearing, Testimony of Louis Freeh". 9/11 Commission. April 13, 2004. Retrieved September 3, 2011.
"Jihad Against Jews and Crusaders: World Islamic Front Statement". Federation of American Scientists. February 23, 1998. Retrieved September 3, 2011.
44.Jump up ^ bin Laden, Osama (November 24, 2002). "Full text: bin Laden's 'letter to America'". The Observer. Retrieved September 3, 2011.
45.^ Jump up to: a b Mearsheimer (2007), p. 67.
Kushner (2003), p. 389.
Murdico (2003), p. 64.
Kelley (2006), p. 207.
Ibrahim (2007), p. 276.
Berner (2007), p. 80.
46.Jump up ^ "Full transcript of bin Ladin's speech". aljazeera. Retrieved April 10, 2012.
bin Laden, Osama (November 24, 2002). "Full text: bin Laden's 'letter to America'". The Observer. Retrieved September 3, 2011.
47.Jump up ^ "Full transcript of bin Laden's "Letter to America"". The Guardian. November 24, 2002. Retrieved September 3, 2011.
48.Jump up ^ bin Laden, Osama. "Full transcript of bin Ladin's speech". Al Jazeera. Retrieved April 10, 2012. "So I shall talk to you about the story behind those events and shall tell you truthfully about the moments in which the decision was taken, for you to consider"
49.Jump up ^ Bergen (2001), p. 3.
50.^ Jump up to: a b c "1998 Al Qaeda fatwā". Fas.org. February 23, 1998. Retrieved September 3, 2011.
51.^ Jump up to: a b Yusufzai, Rahimullah (September 26, 2001). "Face to face with Osama". The Guardian (London). Retrieved September 3, 2011.
52.Jump up ^ Pape, Robert A. (2005). Dying to Win: The Strategic Logic of Suicide Terrorism. New York: Random House. ISBN 0-8129-7338-0.
53.Jump up ^ See also the 1998 Al-Qaeda fatwā: "The ruling to kill the Americans and their allies – civilians and military – is an individual duty for every Muslim who can do it in any country in which it is possible to do it, in order to liberate the al-Aqsa Mosque and the holy mosque [Mecca] from their grip, and in order for their armies to move out of all the lands of Islam, defeated and unable to threaten any Muslim." Quoted from "Al Qaeda's Second Fatwa". PBS NewsHour. Public Broadcasting Service. Archived from the original on 2013-11-28. Retrieved May 29, 2014.
54.Jump up ^ Summers and Swan (2011), pp. 211, 506n.
55.Jump up ^ Lawrence (2005), p. 239.
56.Jump up ^ online here)
57.Jump up ^ In his taped broadcast from January 2010, Bin Laden said "Our attacks against you [the United States] will continue as long as U.S. support for Israel continues. ... The message sent to you with the attempt by the hero Nigerian Umar Farouk Abdulmutallab is a confirmation of our previous message conveyed by the heroes of September 11". Quoted from "Bin Laden: Attacks on U.S. to go on as long as it supports Israel", in Haaretz.com
58.Jump up ^ Rockmore, Tom (April 21, 2011). Before and After 9/11: A Philosophical Examination of Globalization, Terror. ISBN 978-1-4411-1892-9. Retrieved September 11, 2011.
59.Jump up ^ Bernard Lewis, 2004. In Bernard Lewis's 2004 book The Crisis of Islam: Holy War and Unholy Terror, he argues that animosity toward the West is best understood with the decline of the once powerful Ottoman empire, compounded by the import of western ideas — Arab socialism, Arab liberalism and Arab secularism. During the past three centuries, according to this interpretation, the Islamic world has lost its dominance and its leadership, and has fallen behind both the modern West and the rapidly modernizing Orient. The resulting, widening gap poses increasingly acute problems, both practical and emotional, for which the rulers, thinkers, and rebels of Islam have not yet found effective answers.
60.Jump up ^ In an essay titled "The spirit of terrorism", Jean Baudrillard described 9/11 as the first global event that "questions the very process of globalization". Baudrillard. "The spirit of terrorism". Retrieved June 26, 2011.
61.Jump up ^ In an essay entitled "Somebody Else's Civil War", Michael Scott Doran argues the attacks are best understood as part of a religious conflict within the Muslim world and that Bin Laden's followers "consider themselves an island of true believers surrounded by a sea of iniquity". Hoping that U.S. retaliation would unite the faithful against the West, bin Laden sought to spark revolutions in Arab nations and elsewhere. Doran argues the Osama bin Laden videos attempt to provoke a visceral reaction in the Middle East and ensure that Muslim citizens would react as violently as possible to an increase in U.S. involvement in their region. ("Somebody Else's Civil War". Foreign Affairs. Retrieved December 5, 2009. Reprinted in Hoge, James F.; Rose, Gideon (2005). Understanding the War on Terror. New York: Norton. pp. 72–75. ISBN 978-0-87609-347-4.)
62.Jump up ^ In The Osama bin Laden I Know, Peter Bergen argues the attacks were part of a plan to cause the United States to increase its military and cultural presence in the Middle East, thereby forcing Muslims to confront the idea of a non-Muslim government and to eventually establish conservative Islamic governments in the region.(Bergen (2006), p. 229.)
63.Jump up ^ "Suspect 'reveals 9/11 planning'". BBC News. September 22, 2003. Retrieved September 3, 2011.
64.^ Jump up to: a b c d 9/11 Commission Report, Chapter 5, pp ??
65.Jump up ^ Lichtblau, Eric (March 20, 2003). "Bin Laden Chose 9/11 Targets, Al Qaeda Leader Says". New York Times. Retrieved September 3, 2011.
66.Jump up ^ Wright (2006), p. 308.
67.Jump up ^ Bergen (2006), p. 283.
68.Jump up ^ Wright (2006), pp. 309–315.
69.Jump up ^ McDermott (2005), pp. 191–2.
70.Jump up ^ Bernstein, Richard (September 10, 2002). "On Path to the U.S. Skies, Plot Leader Met bin Laden". New York Times. Retrieved September 3, 2011.
71.Jump up ^ Wright (2006), pp. 304–7.
72.Jump up ^ Wright (2006), p. 302.
73.Jump up ^ "9/11 commission staff statement No. 16". 9/11 Commission. June 16, 2004. Retrieved September 11, 2012.
74.Jump up ^ "Staff Monograph on 9/11 and Terrorist Travel" (PDF). 9/11 Commission. 2004. Retrieved September 3, 2011.
75.Jump up ^ Irujo, Jose Maria (March 21, 2004). "Atta recibió en Tarragona joyas para que los miembros del 'comando' del 11-S se hiciesen pasar por ricos saudíes" (in Spanish). El Pais. Retrieved April 10, 2012.
76.^ Jump up to: a b c 9/11 Commission Report, pp. 4–14.
77.^ Jump up to: a b "The Attack Looms". 9/11 Commission Report. National Commission on Terrorist Attacks Upon the United States. 2004. Retrieved September 1, 2011.
78.Jump up ^ See, for example, news coverage by CNN: "Breaking News Videos from CNN.com". CNN.
79.Jump up ^ Jones, Jonathan. "The 9/11 attack seen from space – an image of impotence". The Guardian. Archived from the original on 12 March 2014.
80.Jump up ^ "Flight Path Study – American Airlines Flight 11" (PDF). National Transportation Safety Board. February 19, 2002.
81.Jump up ^ "Flight Path Study – United Airlines Flight 175" (PDF). National Transportation Safety Board. February 19, 2002.
82.Jump up ^ "Flight Path Study – American Airlines Flight 77" (PDF). National Transportation Safety Board. February 19, 2002.
83.Jump up ^ Snyder, David (April 19, 2002). "Families Hear Flight 93's Final Moments". The Washington Post. Retrieved November 12, 2013.
84.Jump up ^ "Text of Flight 93 Recording". Fox News. April 12, 2006. Retrieved November 11, 2013.
85.Jump up ^ "The Flight 93 Story". National Park Service. Retrieved September 21, 2011.
86.Jump up ^ McKinnon, Jim (September 16, 2001). "The phone line from Flight 93 was still open when a GTE operator heard Todd Beamer say: 'Are you guys ready? Let's roll'". Pittsburgh Post-Gazette. Retrieved April 10, 2011.
87.Jump up ^ "Relatives wait for news as rescuers dig". CNN. September 13, 2001. Retrieved November 11, 2013.
88.Jump up ^ Summers and Swan (2011), pp. 58, 463n, 476n.
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279.Jump up ^ "Foresight-and Hindsight". National Commission on Terrorist Attacks Upon the United States. National Commission on Terrorist Attacks Upon the United States. Retrieved September 4, 2011.
280.Jump up ^ Bennett, Brian (August 30, 2011). "Post-9/11 assessment sees major security gaps". Los Angeles Times. Retrieved September 4, 2011.
281.Jump up ^ "9/11: Truth, Lies and Conspiracy Interview: Lee Hamilton". CBC News, Canada. August 21, 2006. Archived from the original on Jan 8, 2007. Retrieved July 28, 2010.
282.Jump up ^ "NIST's World Trade Center Investigation". National Institute of Standards and Technology. U.S. Department of Commerce. December 14, 2007. Retrieved September 4, 2011.
283.^ Jump up to: a b "NIST WTC 7 Investigation Finds Building Fires Caused Collapse". The National Institute of Standards and Technology. Retrieved September 4, 2011.
284.Jump up ^ National Construction Safety Team (September 2005). Executive Summary (PDF). "Final Report on the Collapse of the World Trade Center Towers". National Institute of Standards and Technology (United States Department of Commerce). Retrieved April 10, 2011.
285.Jump up ^ Irfanoglu, A.; Hoffmann, C. M. (2008). "Engineering Perspective of the Collapse of WTC-I". Journal of Performance of Constructed Facilities (American Society of Civil Engineers) 22: 62. doi:10.1061/(ASCE)0887-3828(2008)22:1(62). "As the aircraft debris went through several stories in the tower, much of the thermal insulation on the core columns would have been scoured off. Under such conditions, the ensuing fire would be sufficient to cause instability and initiate collapse. From an engineering perspective, impact damage to the core structure had a negligible effect on the critical thermal load required to initiate collapse in the core structure."
286.Jump up ^ Tally, Steve (June 12, 2007). "Purdue creates scientifically based animation of 9/11 attack". Purdue News Service. Retrieved September 4, 2011. "The aircraft moved through the building as if it were a hot and fast lava flow," Sozen says. "Consequently, much of the fireproofing insulation was ripped off the structure. Even if all of the columns and girders had survived the impact – an unlikely event – the structure would fail as the result of a buckling of the columns. The heat from an ordinary office fire would suffice to soften and weaken the unprotected steel. Evaluation of the effects of the fire on the core column structure, with the insulation removed by the impact, showed that collapse would follow whatever the number of columns cut at the time of the impact."
287.Jump up ^ Sigmund, Pete (September 25, 2002). "Building a Terror-Proof Skyscraper: Experts Debate Feasibility, Options". Retrieved April 11, 2012.
288.Jump up ^ "Translating WTC Recommendations Into Model Building Codes". National Institute of Standards and Technology. October 25, 2007. Archived from the original on 2011-03-10. Retrieved September 4, 2011.
289.Jump up ^ Taylor, Tess (September 26, 2001). "Rebuilding in New York" (68). Architecture Week. Retrieved September 4, 2011.
290.Jump up ^ Oglesby, Christy (September 11, 2002). "Phoenix rises: Pentagon honors 'hard-hat patriots'". CNN. Archived from the original on 2004-12-18. Retrieved May 29, 2014.
291.Jump up ^ Bagli, Charles V. (September 22, 2006). "An Agreement Is Formalized on Rebuilding at Ground Zero". The New York Times. Retrieved September 4, 2011.
292.Jump up ^ Dunlap, David W.; Collins, Glenn (June 28, 2006). "Revised Design for Freedom Tower Unveiled". The New York Times. Retrieved September 4, 2011.
293.Jump up ^ "Lower Manhattan: Current Construction". Lower Manhattan Construction Command Center. Retrieved September 8, 2011.
294.Jump up ^ Sigmund, Pete. "Crews Assist Rescuers in Massive WTC Search". Construction Equipment Guide. Retrieved September 4, 2011.
295.Jump up ^ "Tribute in light to New York victims". BBC News. March 6, 2002. Retrieved April 1, 2012.
296.Jump up ^ "About the World Trade Center Site Memorial Competition". World Trade Center Site Memorial Competition. Retrieved September 4, 2011.
297.Jump up ^ "WTC Memorial Construction Begins". CBS News. Associated Press. March 6, 2006. Retrieved September 4, 2011.
298.Jump up ^ Dunlap, David (September 25, 2005). "Governor Bars Freedom Center at Ground Zero". The New York Times. Retrieved September 4, 2011.
299.Jump up ^ Miroff, Nick (September 11, 2008). "Creating a Place Like No Other". The Washington Post (The Washington Post Company). Retrieved September 4, 2011.
300.Jump up ^ Miroff, Nick (September 12, 2008). "A Long-Awaited Opening, Bringing Closure to Many". The Washington Post (The Washington Post Company). Retrieved September 4, 2011.
301.Jump up ^ Dwyer, Timothy (May 26, 2007). "Pentagon Memorial Progress Is Step Forward for Families". The Washington Post. Retrieved September 4, 2011.
302.Jump up ^ "DefenseLINK News Photos – Pentagon's America's Heroes Memorial". Department of Defense. Retrieved September 4, 2011.
303.Jump up ^ "Sept. 11 Flight 93 Memorial Design Chosen". Fox News. Associated Press. September 8, 2005. Retrieved September 4, 2011.
304.Jump up ^ "Flight 93 Memorial Project". Flight 93 Memorial Project / National Park Service. Archived from the original on 2008-04-11. Retrieved September 4, 2011.
305.Jump up ^ Nephin, Dan (August 24, 2008). "Steel cross goes up near flight's 9/11 Pa. crash site". Associated Press. Retrieved September 5, 2011.
306.Jump up ^ Gaskell, Stephanie (August 25, 2008). "Pa. site of 9/11 crash gets WTC beam". New York Daily news. Retrieved September 4, 2011.
307.Jump up ^ Fessenden, Ford (November 18, 2002). "9/11; After the World Gave: Where $2 Billion in Kindness Ended Up". The New York Times. Retrieved September 4, 2011.
308.Jump up ^ Newman, Andy (September 11, 2010). "At a Memorial Ceremony, Loss and Tension". The New York Times.
Bibliography
"Chapter 1.1: 'We Have Some Planes': Inside the Four Flights" (PDF). 9/11 Commission Report. National Commission on Terrorist Attacks Upon the United States. 2004.
Alavosius, Mark P.; Rodriquez, Nischal J. (2005). "Unity of Purpose/Unity of Effort: Private-Sector Preparedness in Times of Terror". Disaster Prevention & Management 14 (5): 666. doi:10.1108/09653560510634098.
"American Airlines Flight 77 FDR Report" (PDF). National Transportation Safety Board. January 31, 2002. Retrieved September 3, 2011.
Averill, Jason D. (2005). Final Reports of the Federal Building and Fire Investigation of the World Trade Center Disaster (PDF). National Institute of Standards and Technology (NIST). Archived from the original on 2009-05-09. Retrieved September 2, 2011.
Bergen, Peter L. (2001). Holy War, Inc.: Inside the Secret World of Osama Bin Laden. Simon and Schuster. ISBN 978-0-7432-3467-2.
Bergen, Peter (2006). The Osama Bin Laden I Know: An Oral History of Al Qaeda's Leader. Simon and Schuster. ISBN 978-0-7432-9592-5.
Berner, Brad (2007). The World According to Al Qaeda. Peacock Books. ISBN 978-81-248-0114-7.
Dwyer, Jim; Flynn, Kevin (2005). 102 Minutes. Times Books. ISBN 978-0-8050-7682-0.
"Final Report on the Collapse of World Trade Center Building 7" (PDF). National Institute of Standards and Technology. November 2008. Retrieved April 11, 2012.
"Flight Path Study – American Airlines Flight 77" (PDF). National Transportation Safety Board. February 19, 2002. Retrieved September 3, 2011.
Fouda, Yosri; Fielding, Nick (2004). Masterminds of Terror: The Truth Behind the Most Devastating Terrorist Attack the World Has Ever Seen. Arcade Publishing. ISBN 978-1-55970-717-6.
Goldberg, Alfred (2007). Pentagon 9/11. Washington, D.C.: Government Printing Office. ISBN 978-0-16-078328-9.
Gunaratna, Ronan (2002). Inside Al Qaeda: global network of terror. Columbia University Press. ISBN 978-0-231-12692-2.
Holmes, Stephen (2006). "Al Qaeda, September 11, 2001". In Diego Gambetta. Making sense of suicide missions. Oxford University Press. ISBN 978-0-19-929797-9.
Ibrahim, Raymond; Osama Bin Laden (2007). The Al Qaeda reader. Random House Digital, Inc. ISBN 978-0-385-51655-6.
Kelley, Christopher (2006). Executing the Constitution: putting the president back into the Constitution. SUNY Press. ISBN 978-0-7914-6727-5.
Keppel, Gilles; Milelli, Jean-Pierre and Ghazaleh, Pascale (2008). Al Qaeda in its own words. Harvard University Press. ISBN 978-0-674-02804-3.
Kushner, Harvey (2003). Encyclopedia of terrorism. SAGE. ISBN 978-0-7619-2408-1.
Lawrence, Bruce; Bruce Lawrence (2005). Messages to the world: the statements of Osama Bin Laden. Verso. ISBN 978-1-84467-045-1. Retrieved May 29, 2014.
McDermott, Terry (2005). Perfect Soldiers: The 9/11 Hijackers. HarperCollins. pp. 191–192. ISBN 978-0-06-058470-2.
"McKinsey Report". FDNY / McKinsey & Company. August 9, 2002. Retrieved September 25, 2011.
Mearsheimer, John J. (2007). The Israel Lobby and U.S. Foreign Policy. Macmillan. ISBN 978-0-374-17772-0.
Murdico, Suzanne (2003). Osama Bin Laden. Rosen Publishing Group. ISBN 978-0-8239-4467-5.
"The Pentagon Building Performance Report" (PDF). American Society of Civil Engineers (ASCE). January 2003. Archived from the original on 2011-07-21. Retrieved September 3, 2011.
Summers, Anthony; Swan, Robbyn (2011). The Eleventh Day: The Full Story of 9/11 and Osama Bin Laden. New York: Ballantine Books. ISBN 1-4000-6659-X.
Sunder, Shyam S. (2005). Final Report on the Collapse of the World Trade Center Towers. National Institute of Standards and Technology (NIST). Retrieved September 2, 2011.
"World Trade Center Building Performance Study – Bankers Trust Building" (PDF). FEMA. May 2002. Retrieved July 12, 2007.
"World Trade Center Building Performance Study – Peripheral Buildings" (PDF). FEMA. May 2002. Retrieved September 3, 2011.
"World Trade Center Building Performance Study" (PDF). Ch. 5 WTC 7 – section 5.5.4. Federal Emergency Management Agency. 2002. Retrieved September 2, 2011.
Wright, Lawrence (2006). The Looming Tower|The Looming Tower: Al-Qaeda and the Road to 9/11. Knopf. ISBN 978-0-375-41486-2.
Further reading
"The 9/11 Commission Report: Final Report of the National Commission on Terrorist Attacks Upon the United States". National Commission O Terrorist Attacks (Cosimo, Inc). July 30, 2010. ISBN 978-1-61640-219-8.
Atkins, Stephen E (2011). The 9/11 Encyclopedia. ABC-CLIO. ISBN 978-1-59884-921-9.
Bolton, M. Kent (2006). U.S. National Security and Foreign Policymaking After 9/11: Present at the Re-creation. Rowman & Littlefield. ISBN 978-0-7425-5900-4.
Caraley, Demetrios (2002). September 11, terrorist attacks, and U.S. foreign policy. Academy of Political Science. ISBN 978-1-884853-01-2.
Chernick, Howard (2005). Resilient city: the economic impact of 9/11. Russell Sage Foundation. ISBN 978-0-87154-170-3.
Damico, Amy M; Quay, Sara E. (2010). September 11 in Popular Culture: A Guide. Greenwood. ISBN 978-0-313-35505-9.
Hampton, Wilborn (2003). September 11, 2001: attack on New York City. Candlewick Press. ISBN 978-0-7636-1949-7.
Langley, Andrew (2006). September 11: Attack on America. Compass Point Books. ISBN 978-0-7565-1620-8.
Neria, Yuval; Gross, Raz; Marshall, Randall D.; Susser, Ezra S. (2006). 9/11: mental health in the wake of terrorist attacks. Cambridge University Press. ISBN 978-0-521-83191-8.
Strasser, Steven; Whitney, Craig R; United States. Congress. Senate. Select Committee on Intelligence, National Commission on Terrorist Attacks upon the United States (2004). The 9/11 investigations: staff reports of the 9/11 Commission: excerpts from the House-Senate joint inquiry report on 9/11: testimony from fourteen key witnesses, including Richard Clarke, George Tenet, and Condoleezza Rice. PublicAffairs. ISBN 978-1-58648-279-4.
External links
General
Find more about September 11 at Wikipedia's sister projects
 Definitions and translations from Wiktionary
 Media from Commons
 Quotations from Wikiquote
 Source texts from Wikisource
 Textbooks from Wikibooks
 Learning resources from Wikiversity
National Commission on Terrorist Attacks Upon the United States official commission website
National September 11th Memorial and Museum – List of victims
September 11, 2001, Documentary Project from the U.S. Library of Congress, Memory.loc.gov
September 11, 2001, Web Archive from the U.S. Library of Congress, Minerva
The September 11th Sourcebooks from The National Security Archive
September 11 Digital Archive: Saving the Histories of September 11, 2001 from the Center for History and New Media and the American Social History Project/Center for Media and Learning
DoD: Khalid Sheikh Mohammed Verbatim Transcript of Combatant Status Review Tribunal Hearing for ISN 10024, From WikiSource
Multimedia
Understanding 9/11 – A Television News Archive at Internet Archive
CNN.com – Video archive, including the first and second planes.
Remembering 9/11 – National Geographic Society
Latest video of Sept 9/11 attack emerges published by International Business Times HK
Time.com – 'Shattered: a remarkable collection of photographs', James Nachtwey
September 11, 2001 Screenshot Archive – Database of 230 screenshots from news sites around the world.
September 11 attacks in the Newseum archive of front page images from 2001-09-12.


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