Question: When did Columbia tear apart in reentry?

Space Shuttle Challenger disaster

Space Shuttle ''Challenger'' disaster


On January 28, 1986, the NASA shuttle orbiter mission STS-51-L and the tenth flight of Space ShuttleChallenger (OV-99) broke apart 73 seconds into its flight, killing all seven crew members, which consisted of five NASA astronauts and two payload specialists. The spacecraft disintegrated over the Atlantic Ocean, off the coast of Cape Canaveral, Florida, at 11:39a.m. EST (16:39 UTC). The disintegration of the vehicle began after a joint in its right solid rocket booster (SRB) failed at liftoff. The failure was caused by the failure of O-ring seals used in the joint that were not designed to handle the unusually cold conditions that existed at this launch. The seals' failure caused a breach in the SRB joint, allowing pressurized burning gas from within the solid rocket motor to reach the outside and impinge upon the adjacent SRB aft field joint attachment hardware and external fuel tank. This led to the separation of the right-hand SRB's aft field joint 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,[1][2] and the impact of the crew compartment at terminal velocity with the ocean surface was too violent to be survivable.[3]
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,[4] with the agency violating its own safety rules. NASA managers had known since 1977 that contractor Morton-Thiokol's design of the SRBs contained a potentially catastrophic flaw in the O-rings, but they had failed to address this problem properly. NASA managers also disregarded warnings 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.
Approximately 17percent of Americans witnessed the launch live because of the presence of Payload Specialist Christa McAuliffe, who would have been the first teacher in space. Media coverage of the accident was extensive: one study reported that 85percent of Americans surveyed had heard the news within an hour of the accident.[5] The Challenger disaster has been used as a case study in many discussions of engineering safety and workplace ethics.
O-ring concerns

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.)[6] The seals of all of the SRB joints were required to contain the hot, high-pressure gases produced by the burning solid propellant inside, thus forcing them 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.[7] 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.[8]
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.[9]
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.[9]
After the 1984 launch of STS-41-D, flown by Discovery, the first occurrence of hot gas "blow-by" was discovered beyond the primary O-ring. In the post-flight analysis, Thiokol engineers found that the amount of blow-by was relatively small and had not impinged upon the secondary O-ring, and concluded that for future flights, the damage was an acceptable risk. However, after the Challenger disaster, Thiokol engineer Brian Russell identified this event as the first "big red flag" regarding O-ring safety.[10]
By 1985, with seven of nine shuttle launches that year using boosters displaying O-ring erosion and/or hot gas blow-by,[11] Marshall and Thiokol realized that they had a potentially catastrophic problem on their hands. Perhaps most concerning was the launch of STS-51-B in April 1985, flown by Challenger, in which the worst O-ring damage to date was discovered in post-flight analysis. The primary O-ring of the left nozzle had been eroded so extensively that it had failed to seal, and for the first time hot gases had eroded the secondary O-ring.[12] They began the process of redesigning the joint with three inches (76mm) 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".[9] 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
Delays
Challenger was originally set to launch from KSC in Florida at 14:42 Eastern Standard Time (EST) on January 22, 1986. Delays in the previous mission, STS-61-C, caused the launch date to be moved to January 23 and then to January 24. The 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.[13]
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.[14] Then, a stripped bolt prevented the closeout crew from removing a closing fixture from the orbiter's hatch.[15] 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.[16] While the crew waited for winds to die down, the launch window expired, forcing yet another scrub.
Thiokol–NASA conference call
Forecasts for January 28 predicted an unusually cold morning, with temperatures close to −1°C (30°F), the minimum temperature permitted for launch. The Shuttle 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.[17][18]
By mid-1985 Thiokol engineers worried that others did not share their concerns about the low temperature effects on the boosters. Bob Ebeling in October 1985 wrote a memo—titled "Help!" so others would read it—of concerns regarding low temperatures and O-rings. After the weather forecast, NASA personnel remembered Thiokol's warnings and contacted the company. When a Thiokol manager asked Ebeling about the possibility of a launch at 18°F (−8°C), he answered "[W]e're only qualified to 40° [40°F or 4°C]... 'what business does anyone even have thinking about 18°, we're in no-man's land.'" After his team agreed that a launch risked disaster, Thiokol immediately called NASA recommending a postponement until temperatures rose in the afternoon. NASA manager Jud Lovingood responded that Thiokol could not make the recommendation without providing a safe temperature. The company prepared for a teleconference two hours later during which it would have to justify a no-launch recommendation.[17][18]
At the 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 Ebeling and Roger Boisjoly) reiterated 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.[18] They argued that they did not have enough data to determine whether the joints would properly seal if the O-rings were colder than 54°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 could destroy the Orbiter and kill 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?"[18] NASA believed that Thiokol's hastily prepared presentation's quality was too poor to support such a statement on flight safety.[17] 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.
NASA claimed that it 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, additionally viewed the large amount of ice present on the pad as a constraint to launch.
According to Ebeling, a second conference call was scheduled with only NASA & Thiokol management, excluding the engineers. For reasons that are unclear, Thiokol management disregarded its own engineers' warnings and now recommended that the launch proceed as scheduled;[18][19] NASA did not ask why.[17] Ebeling told his wife that night that Challenger would blow up.[20]
Ken Iliff, a former NASA Chief Scientist who had worked on the Space Shuttle Program since its first mission (and the X-15 program before that), stated in 2004, "Violating a couple of mission rules was the primary cause of the Challenger accident."[21]
Ice

The Thiokol engineers had also argued that the low overnight temperatures of 18°F (−8°C) the evening prior to launch would almost certainly result in SRB temperatures below their redline of 39°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 9°F (−13°C). This was believed to be the result of supercooled air blowing on the joint from the liquid oxygen (LOX) tank vent. It was much lower than the air temperature and far below the design specifications for the O-rings. The low 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.
The temperature on the day of the launch was far lower than had been the case with previous launches: below freezing at 28.0 to 28.9°F (−2.2 to −1.7°C); previously, the coldest launch had been at 54°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. 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 cleared to launch at 11:38am EST.[19]

January 28 launch and failure

Liftoff and initial ascent



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.[22] All times are given in seconds after launch and correspond to the telemetry time-codes from the closest instrumented event to each described event.[23]
The Space Shuttle main engines (SSMEs) were ignited at T -6.6 seconds. The SSMEs were liquid-fueled and could be safely shut down (and the launch aborted if necessary) until the Solid Rocket Boosters ignited at T=0 (which was at 11:38:00.010 EST) and the hold-down bolts were released with explosives, freeing the vehicle from the pad. At lift off, the three SSMEs were at 100% of their original rated performance, and began throttling up to 104% under computer control. 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.[23] 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.[24]

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 attached 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 temperature had dropped below the glass transition temperature of the O-rings. Above the glass transition temperature, the O-rings display properties of elasticity and flexibility, while below the glass transition temperature, they become rigid and brittle. 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. Aluminum oxides from the burned solid propellant sealed the damaged joint, temporarily replacing the O-ring seal before flame passed 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, per normal operating procedure. At T+35.379, the SSMEs throttled back further to the planned 65%. Five seconds later, at about 19,000 feet (5,800m), 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

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.[25]
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 SRB 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 passing 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.[22]
At T+64.660, the plume suddenly changed shape, indicating that a leak had begun in the liquid hydrogen (LH2) 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 LH2 tank began to drop at T+66.764, indicating the effect of the leak.[22]
At this stage the situation still seemed normal both to the crew 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, "Roger, go at throttle up"; this was the last communication from Challenger on the air-to-ground loop.[22]
Vehicle breakup


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."[26] 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 rammed the hydrogen tank into the LOX 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. The external tank at this point suffered a complete structural failure, the LH2 and LOX tanks rupturing, mixing, and igniting, creating a fireball that enveloped the whole stack.[27]
The breakup of the vehicle began at T+73.162 seconds and at an altitude of 48,000 feet (15km).[28] 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 ripped apart by abnormal aerodynamic forces (contrary to popular belief, the orbiter did not explode as the force of the external tank breakup was well within its structural limits). 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-thick (12.7mm) 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.[24]
The more robustly constructed crew cabin also survived the breakup of the launch vehicle, as it was designed to survive 20psi (140kPa) while the estimated pressure it had been subjected to during orbiter breakup was only about 4–5psi (28–34kPa). 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.[24] Twenty-five seconds after the breakup of the vehicle, the altitude of the crew compartment peaked at a height of 65,000 feet (20km).[28] The cabin was stabilized during descent by the large mass of electrical wires trailing behind it. At T+76.437 the nose caps and drogue parachutes of the SRBs separated, as designed, and the drogue of the right-hand SRB was seen by a tracking camera, bearing the frustum and its location aids.[29]
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 was destroyed a few seconds later, "we all knew exactly what happened."[18]
Post-breakup flight controller dialogue

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+oxygen 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. Moments 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.[30] The SRBs were close to the end of their scheduled burn (110 seconds after launch) and had nearly exhausted their propellants when the destruct command was sent, so very little, if any, explosive force was generated by this event.
Public affairs officer Steve Nesbitt reported: "Flight controllers here are looking very carefully at the situation. Obviously a major malfunction. We have no downlink."[22]
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.[31]
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 the recovery forces to see what can be done at this point."[22]
Cause and time of death

The crew cabin, made of reinforced aluminum, was a particularly robust section of the orbiter.[32] 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 10 seconds the cabin was in free fall. The forces involved at this stage were probably insufficient to cause major injury.
At least some of the crew were probably 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.[33] These were those of Judith Resnik, mission specialist Ellison Onizuka, and pilot Michael J. Smith.[34] The location of Smith's activation switch, on the back side of his seat, likely indicated that either Resnik or Onizuka activated it for him.  Mike Mullane writes: "There had been nothing in our training concerning the activation of a PEAP in the event of an in-flight emergency. The fact that Judy or El had done so for Mike Smith made them heroic in my mind."[34] Investigators found their remaining unused air supply consistent with the expected consumption during the 2-minute-and-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.[35]
Whether the crew members 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, they may have been conscious for the entire fall until impact. Recovery of the cabin found that the middeck floor had not suffered buckling or tearing, as would result from a rapid decompression, thus providing some evidence that the depressurization may have not happened all at once.
NASA routinely trained shuttle crews for splashdown events, but the cabin hit the ocean surface at roughly 207mph (333km/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, and far greater than almost any automobile, aircraft, or train accident. The crew would have been torn from their seats and killed instantly by the extreme impact force.[28]
On July 28, 1986, NASA's Associate Administrator for Space Flight, former astronaut Richard H. Truly, released a report on the deaths of the crew from the director of Space and Life Sciences at the Johnson Space Center, Joseph P. Kerwin. A medical doctor and former astronaut, Kerwin was a veteran of the 1973 Skylab 2 mission. 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.[28]

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, "I not only flew with Dick Scobee, we owned a plane together, and I know Scob did everything he could to save his crew. Scob fought for any and every edge to survive. He flew that ship without wings all the way down ... they were alive."[32]
Prospect of crew escape

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 for the two-man crews 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.) The multi-deck design of the crew cabin precluded use of such ejection seats for larger crews. Providing some sort of launch escape system had been considered, but deemed impractical due to "limited utility, technical complexity and excessive cost in dollars, weight or schedule delays."[30]
After the loss of Challenger, the question was re-opened, and NASA considered several different options, including ejector seats, tractor rockets and emergency egress through the bottom of the orbiter. 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, but this system would not have been usable in the Challenger situation.[36]
Aftermath
Tributes


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.[37][38] 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.'[39]



Three days later, Reagan and his wife Nancy traveled to the Johnson Space Center to speak at a memorial service honoring the crew members, 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.[40]

It was attended by 6,000 NASA employees and 4,000 guests,[41][42] as well as by the families of the crew.[43] 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.[41][42] All activities were broadcast live by the national television networks.[41]
President Reagan would further mention the Challenger crew members at the beginning of his State of the Union address on February 4.
The astronauts' names are among those of several astronauts and cosmonauts who have died in the line of duty, listed on the Space Mirror Memorial at the Kennedy Space Center Visitor Complex in Merritt Island, Florida.
Recovery of debris and crew

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 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.[44]
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."[44] This phase of operations lasted until February 7. In order to discourage scavengers, NASA did not disclose the exact location of the debris field and insisted on secrecy, utilizing code names such as "Target 67" to refer the crew cabin and "Tom O'Malley" to refer to any crew remains.[45] RadioShack stores in the Cape Canaveral area were soon completely sold out of radios that could tune into the frequency used by Coast Guard vessels.[45] 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 486 square nautical miles (1,670km2), and took place at water depths between 70 feet (21m) and 1,200 feet (370m).[46] On March 7, divers from the USS Preserver identified what might be the crew compartment on the ocean floor.[47][48] 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.[49] The crew cabin was severely crushed and fragmented from the extreme impact forces; one member of the search team described it as "largely a pile of rubble with wires protruding from it". The largest intact section was the rear wall containing the two payload bay windows and the airlock. All windows in the cabin had been destroyed, with only small bits of glass still attached to the frames. Impact forces appeared to be greatest on the left side, indicating that it had struck the water in a nose-down, left-end-first position.

Inside the twisted debris of the crew cabin were the bodies of the astronauts, which after weeks of immersion in salt water and exposure to scavenging marine life were in a "semi-liquefied state that bore little resemblance to anything living", although according to John Devlin, the skipper of the USS Preserver, they "were not as badly mangled as you'd see in some aircraft accidents". Lt. Cmdr James Simpson of the Coast Guard reported finding a helmet with ears and a scalp in it.[50] Judith Resnik was the first to be removed followed by Christa McAuliffe, with more remains retrieved over several hours. Due to the hazardous nature of the recovery operation (the cabin was filled with large pieces of protruding jagged metal), the Navy divers protested that they would not go on with the work unless the cabin was hauled onto the ship's deck.
During the recovery of 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, it was seen floating on the ocean's surface. It sank as a team prepared to pull it from the water. Determined not to end the recovery operations without retrieving Jarvis, astronaut Robert Crippen rented a fishing boat at his own expense and went searching for the body. On April 15, near the end of the salvage operations, the Navy divers found Jarvis. His body had settled to the sea floor, 101.2 feet (30.8m) below the surface, some 0.7 nautical miles (1.3km; 0.81mi) from the final resting place of the crew compartment. The body was recovered and brought to the surface before being processed with the other crew members and then prepared for release to Jarvis's family.[51]
Navy pathologists performed autopsies on the crew members, but due to the poor condition of the bodies, the exact cause of death could not be determined for any of them. The crew transfer took place on April 29, 1986, three months and one day after the accident. Seven hearses carried the crew's 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 crew's remains were aboard the jet, they were flown to Dover Air Force Base in Delaware to be processed and then released to their relatives.
It had been suggested early in the investigation that the accident was caused by inadvertent detonation of the Range Safety destruct charges on the external tank, but the charges were recovered mostly intact and a quick overview of telemetry data immediately ruled out that theory.
The three shuttle main engines were found largely intact and still attached to the thrust assembly despite extensive damage from impact with the ocean, marine life, and immersion in salt water. They had considerable heat damage due to a LOX-rich shutdown caused by the drop in hydrogen fuel pressure as the external tank began to fail. The memory units from Engines 1 and 2 were recovered, cleaned, and their contents analyzed, which confirmed normal engine operation until LH2 starvation began starting at T+72 seconds. Loss of fuel pressure and rising combustion chamber temperatures caused the computers to shut off the engines. Since there was no evidence of abnormal SSME behavior until 72 seconds (only one second or so before the breakup of Challenger ), the engines were ruled out as a contributing factor in the accident.
Other recovered orbiter components showed no indication of pre-breakup malfunction. Recovered parts of the TDRSS satellite also did not disclose any abnormalities other than damage caused by vehicle breakup, impact, and immersion in salt water. The solid rocket motor boost stage for the payload had not ignited either and was quickly ruled out as a cause of the accident.
The solid rocket booster debris had no signs of explosion (other than the Range Safety charges splitting the casings open), or propellant debonding/cracking. There was no question about the RSO manually destroying the SRBs following vehicle breakup, so the idea of the destruct charges accidentally detonating was ruled out. Premature separation of the SRBs from the stack or inadvertent activation of the recovery system was also considered, but telemetry data quickly disproved that idea. Nor was there any evidence of in-flight structural failure since visual and telemetry evidence showed that the SRBs remained structurally intact up to and beyond vehicle breakup. The aft field joint on the right SRB did show extensive burn damage.
Telemetry proved that the right SRB, after the failure of the lower struts, had come loose and struck the external tank. The exact point where the struts broke could not be determined from film of the launch, nor were the struts or the adjacent section of the external tank recovered during salvage operations. Based on the location of the rupture in the right SRB, the P12 strut most likely failed first. The SRB's nose cone also exhibited some impact damage from this behavior (for comparison, the left SRB nose cone had no damage at all) and the intertank region had signs of impact damage as well. In addition, the orbiter's right wing had impact and burn damage from the right SRB colliding with it following vehicle breakup.
Most of the initially considered failure modes were soon ruled out and 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.[44] The recovery operation was able to pull 15 short tons (14t) of debris from the ocean; this means that 55% of Challenger, 5% of the crew cabin and 65% of the satellite cargo are still missing.[52] 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.[53] Under 18 U.S.C. it is against the law to be in possession of Challenger debris, and any newly discovered pieces must be turned over to NASA.[54]
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.[55]
A soccer ball from the personal effects locker of Mission Specialist Ellison Onizuka was also recovered intact from the wreckage, and was later flown to the International Space Station aboard Soyuz Expedition 49 by American astronaut Robert S. Kimbrough. It is currently on display at Clear Lake High School in Houston.[56]
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

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. Ronald McNair was buried in Rest Lawn Memorial Park in Lake City, South Carolina. Christa McAuliffe was buried at Calvary Cemetery in her hometown of Concord, New Hampshire.[57] Gregory Jarvis was cremated, and his ashes scattered in the Pacific Ocean. Unidentified crew remains were buried communally at the Space Shuttle Challenger Memorial in Arlington on May 20, 1986.[58]
Concurrent NASA crises
As a result of the disaster, several National Reconnaissance Office (NRO) satellites that only the shuttle could launch were grounded because of the accident. This is a dilemma the NRO had feared since the 1970s when the shuttle was designated as the United States' primary launch system for all government and commercial payloads.[59][60] Compounding NASA's problems were difficulties with its Titan and Delta rocket programs which suffered other unexpected rocket failures around the time of the Challenger disaster.

On August 28, 1985, a Titan 34D[61] carrying a KH-11 Kennan satellite exploded after liftoff over Vandenberg Air Force Base, when the first stage propellant feed system failed. It was the first failure of a Titan missile since 1978. On April 18, 1986, another Titan 34D-9[61][62] carrying a classified payload,[62] said to be a Big Bird spy satellite, exploded at about 830 feet (250m) 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[61] carrying the GOES-G weather satellite[63] 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 problems in the rockets' designs were solved.
A separate related accident occurred at the Pacific Engineering and Production Company of Nevada (PEPCON) plant in Henderson, Nevada. Due to the shuttle fleet being grounded, excess ammonium perchlorate that was manufactured as rocket fuel was being kept on site. This excess ammonium perchlorate later caught fire and the magnitude of the resulting explosion destroyed the PEPCON facility and the neighboring Kidd & Co marshmallow factory.[64]
Investigation
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."[65] 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.[66][67] "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."[66]
Rogers Commission


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.[68]

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.[9] The report also strongly criticized the decision-making process that led to the launch of Challenger, saying that it was seriously flawed:[19]
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.—Rogers Commission Report Chapter V[19]

Richard Feynman
One of the commission's members was theoretical physicist Richard Feynman. Feynman, who was then seriously ill with cancer, was reluctant to undertake the job. He did so to find the root cause of the disaster, and to speak plainly to the public about his findings.[69] 
Before going to Washington, D.C., Feynman did his own investigation. He became suspicious about the O-rings. “O-rings show scorching in Clovis check,” he scribbled in his notes. “Once a small hole burns through generates a large hole very fast! Few seconds catastrophic failure.”[70] At the start of investigation, fellow members Dr. Sally Ride and General Donald J. Kutyna told Feynman that the O-rings had not been tested at temperatures below 50°F (10°C).[71] During a televised hearing, Feynman 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. While other members of the Commission met with NASA and supplier top management, Feynman sought out the engineers and technicians for the answers.[72] He was critical of flaws in NASA's "safety culture", so much so 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.[72] 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."[73]
U.S. House Committee hearings
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.[74] 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. 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.[74]

NASA and Air Force response

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.[75]
When the disaster happened, 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,[76] costing over $4 billion (equivalent to $9.1billion today). 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.[75] 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 $10million (equivalent to $22.9million today) 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.[77]
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.[78] Former Challenger flight director Jay Greene became chief of the Safety Division of the directorate.[79]
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.[80] In August 1986, President Reagan also announced that the shuttle would no longer carry commercial satellite payloads.[80] 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".[81] 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.[82]
Media coverage
While the presence of New Hampshire's Christa McAuliffe, a member of the Teacher in Space program, 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.[83] Los Angeles station KNBC also carried the launch with anchor Kent Shocknek describing the tragedy as it happened.[84] Live radio coverage of the launch and explosion was heard on ABC Radio anchored by Vic Ratner and Bob Walker.[85] CBS Radio News carried the launch live but cut out of coverage seconds before the explosion necessitating anchor Christopher Glenn to hastily scramble back on the air to report what had happened.[86]
NBC, CBS, and ABC all broke into regular programming shortly after the accident; NBC's John Palmer announced there had been "a major problem" with the launch. Both Palmer and CBS anchor Dan Rather reacted to cameras catching live video of something descending by parachute into the area where Challenger debris was falling with confusion and speculation that a crew member may have ejected from the shuttle and survived. The shuttle had no individual ejection seats or a crew escape capsule. Mission control identified the parachute as a paramedic parachuting into the area but this was also incorrect based on internal speculation at mission control. The chute was the parachute and nose cone from one of the solid rocket boosters which had been destroyed by the range safety officer after the explosion.[87] Due to McAuliffe's presence on the mission, NASA arranged for many US public schools to view the launch live on NASA TV.[88] As a result, many who were schoolchildren in the US in 1986 had the opportunity to view the launch live. After the accident, 17percent of respondents in one study reported that they had seen the shuttle launch, while 85percent 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.)[89] 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."[90] Children were even more likely than adults to have seen the accident live, since many children—48percent of nine- to thirteen-year-olds, according to a New York Times poll—watched the launch at school.[90]
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 1,467 reporters at Kennedy Space Center and another 1,040 at the Johnson Space Center. The event made headlines in newspapers worldwide.[66]
Use as case study
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.[91] 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.[92] 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."[93] 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.[94][95]
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 below the coldest launch, with the worst damage seen to date, that even a casual observer could have determined that the risk of disaster was severe.[96]
Tufte has also argued that poor presentation of information may have also affected NASA decisions during the last flight of the space shuttle Columbia.[97]
Boisjoly, Wade Robison, a Rochester Institute of Technology professor, and their colleagues have vigorously repudiated Tufte's conclusions about the Morton-Thiokol engineers' role in the loss of Challenger. First, they argue 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."[98][99] They further argue that Tufte "misunderstands thoroughly the argument and evidence the engineers gave."[98] 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."[98]
The Challenger disaster also provided a chance to see how traumatic events affected children's psyches. At least one psychological study has found that memories of the Challenger explosion were similar to memories of experiencing single, unrepeated traumas. The majority of children's memories of Challenger were often clear and consistent, and even things like personal placement such as who they were with or what they were doing when they heard the news were remembered well. In one U.S. study, children's memories were recorded and tested again. Children on the East Coast recalled the event more easily than children on the West Coast, due to the time difference. Children on the East Coast either saw the explosion on TV while in school, or heard people talking about it. On the other side of the country, most children were either on their way to school, or just beginning their morning classes. Researchers found that those children who saw the explosion on TV had a more emotional connection to the event, and thus had an easier time remembering it. After one year the children's memories were tested, and those on the East Coast recalled the event better than their West Coast counterparts. Regardless of where they were when it happened, the Challenger explosion was still an important event that many children easily remembered.[100]
Continuation of the Shuttle program
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[101] 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 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.
Other civilian passenger plans
NASA had intended to send a wide range of civilian passengers into space on subsequent flights. These plans were all scrapped immediately following the Challenger disaster.

NBC News' Cape Canaveral correspondent Jay Barbree was among 40 candidates in NASA's Journalist in Space Program. The first journalist was due to fly on the shuttle Challenger in September 1986. In 1984, prior to establishing the Teacher in Space Program (TISP), NASA created the Space Flight Participant Program whose aim was "to select teachers, journalists, artists, and other people who could bring their unique perspective to the human spaceflight experience as a passenger on the space shuttle." Notable among early potential passengers was Caroll Spinney who, from 1969-2018, played the characters Big Bird and Oscar the Grouch on the children's television show Sesame Street.  In 2014, after the situation was mentioned in the documentary "I Am Big Bird", NASA confirmed the revelation, stating: A review of past documentation shows there were initial conversations with Sesame Street regarding their potential participation on a Challenger flight, but that plan was never approved.Spinney went on to say that the Big Bird costuming was prohibitive in the tight quarters of the NASA space shuttles and they had moved on.[102]
Legacy

The families of the Challenger crew organized the Challenger Center for Space Science Education as a permanent memorial to the crew. Forty-three learning centers and one headquarters office have been established by this non-profit organization[103].
The final episode of the second season of Punky Brewster was notable for centering on the very recent, real-life Space Shuttle Challenger disaster. Punky and her classmates watched the live coverage of the shuttle launch in Mike Fulton's class. After the accident occurred, Punky is traumatized, and finds her dreams to become an astronaut are crushed. She writes a letter to NASA, and is visited by special guest star Buzz Aldrin.[104] Although the episode received high ratings, NBC would, in the following weeks, decide to cancel the show.[105]
On the evening of April 5, 1986, the Rendez-vous Houston concert commemorated and celebrated the crew of the Challenger. It featured a live performance by musician Jean Michel Jarre, a friend of crew member Ron McNair. McNair was supposed to play the saxophone from space during the track "Last Rendez-Vous". It was to have become the first musical piece professionally recorded in space. His substitute for the concert was Houston native Kirk Whalum.
In June 1986, singer-songwriter John Denver, a pilot with a deep interest in going to space himself, released the album One World which included the song Flying For Me, a tribute to the Challenger crew.
Star Trek IV: The Voyage Home was dedicated to the crew of the Challenger. Principal photography for The Voyage Home began four weeks after Challenger and her crew were lost.

A unpainted decorative oval in the Brumidi Corridors of the United States Capitol was finished with a portrait depicting the crew by Charles Schmidt in 1987.[106] The scene was painted on canvas and then applied to the wall.[106]
In 1988, seven craters on the far side of the moon, within the Apollo Basin, were named after the fallen astronauts by the IAU.[107]
In Huntsville, Alabama, home of Marshall Space Flight Center, Challenger Elementary School, Challenger Middle School, and the Ronald E. 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 1 astronauts and the final Space Shuttle Columbia crew.) Streets in a neighborhood established in the late-1980s in nearby Decatur are named in memory of each of the Challenger crew members (Onizuka excluded), as well as the three deceased Apollo 1 astronauts. Julian Harris Elementary School is located on McAuliffe Drive, and its mascot is the Challengers.

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.[108] The unit was established in 1992.[109]
In San Antonio, Texas, Scobee Elementary School opened in 1987, the year after the disaster. Students at the school are referred to as "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[110] and Christa McAuliffe Elementary School in Sammamish, Washington.[111] and Dick Scobee Elementary in Auburn, Washington. In San Diego, California, the next-opened public middle school in the San Diego Unified School District was named Challenger Middle School.[112] 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. 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. 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. Another school was opened in Chicago, IL as the Sharon Christa McAuliffe Elementary school.[113] 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.[114] In Boise, ID, Boise High School has a memorial to the Challenger astrounauts. In 1986 in Webster, Texas, the "Challenger Seven Memorial Park" was also dedicated in remembrance of the event.[115] Their Spirits Circle the Earth was installed in Columbus, Ohio, in 1987.
In Port Saint John, Florida within Brevard County the same county that the Kennedy Space Center resides in is the Challenger 7 Elementary School which is named in memory of the seven crew members of STS-51-L.[116] There is also a middle school in neighboring Rockledge, McNair Magnet School, named after astronaut Ronald McNair.[117] 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 Christa McAuliffe. There are also schools in Denver, Colorado; Riverside, California; Saratoga, California; Lowell, Massachusetts; Houston, Texas; 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.[118][119][120] The draw bridge over the barge canal on State Rd.3 on Merritt Island, Florida, is named the Christa McAuliffe Memorial Bridge.[121] In Oxnard, Ca, McAuliffe Elementary School is named after Christa McAuliffe, and bears tribute to the crew of the Challenger flight in its logo, with an image of the Shuttle and the motto "We Meet The Challenge." They crew and mission are also tributed by the schools mascot, The Challengers, and their saying "We Reach for the Stars."[122]
The 1996 science fiction television series Space Cases is set on a spaceship known as the Christa, named in honor of Christa McAuliffe, described in the series as "an Earth teacher who died during the early days of space exploration."
In 1997, playwright Jane Anderson wrote a play inspired by the Challenger incident entitled Defying Gravity.[123]
In 2004, President George W. Bush conferred posthumous Congressional Space Medals of Honor to all 14 crew members lost in the Challenger and Columbia accidents.[124]
In 2009, Allan J. McDonald, former director of the Space Shuttle Solid Motor Rocket Project for Morton-Thiokol, Inc. published his book Truth, Lies, and O-Rings: Inside the Space Shuttle Challenger Disaster. Up to that point, no one directly involved in the decision to launch Challenger had published a memoir about the experience.[125]
In June 14, 2011, Christian electronic/dance pop singer Adam Young, through his electronica project, released a song about the Challenger incident on his third studio album All Things Bright and Beautiful.
In December 2013, Beyoncé released a song titled "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."[126] The song raised controversy, with former NASA astronauts and families labelling Knowles' sample as "insensitive."[127] Hardeep Phull of the New York Post described the sample's presence as "tasteless,"[128] and Keith Cowing of NASA Watch suggested that the usage of the clip ranged from "negligence" to "repugnant."[129] 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."[126][129] 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."[130]
On June 16, 2015, post-metal band Vattnet Viskar released a full-length album titled Settler which was largely inspired by the Challenger accident and Christa McAuliffe in particular. The album was released in Europe on June 29. Guitarist Chris Alfieri stated in a June 17, 2015 interview with Decibel Magazine that, "Christa was from Concord, New Hampshire, the town that I live in. One of my first memories is the Challenger mission's demise, so it's a personal thing for me. But the album isn't about the explosion, it's about everything else. Pushing to become something else, something better. A transformation, and touching the divine."[131]

On July 23, 2015, Australian post-rock band We Lost the Sea released an album titled Departure Songs. Each song on the album was focused around human sacrifice for the greater good, or for the progress of the human race itself. The album features a song titled "Challenger" which is split into two parts: "Flight" and "Swan Song".[132] The song samples audio from NASA, a William S. Burroughs lecture, reactions of people witnessing the disaster and Ronald Reagan's national address.[133]
On June 27, 2015, the "Forever Remembered" exhibit at the Kennedy Space Center Visitor Complex, Florida, opened and includes a display of a section of Challenger's recovered fuselage to memorialize and honor the fallen astronauts. The exhibit was opened by NASA Administrator Charles Bolden along with family members of the crew.[134]
On August 7, 2015 English singer-songwriter Frank Turner released his sixth album Positive Songs for Negative People which includes the song "Silent Key".[135]
The mountain range Challenger Colles on Pluto was named in honor of the victims of the Challenger disaster.
The Challenger Columbia Stadium in League City, Texas is named in honor of the victims of both the Challenger disaster as well as the Columbia disaster in 2003.
A tree for each astronaut was planted in NASA's Astronaut Memorial Grove at the Johnson Space Center in Houston, Texas, not far from the Saturn V building, along with trees for each astronaut from the Apollo 1 and Columbia disasters.[136] Tours of the space center pause briefly near the grove for a moment of silence, and the trees can be seen from nearby NASA Road 1.
Video documentation
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. As of March 15, 2014, eight other motion picture recordings of the event have become publicly available:
a professional black-and-white NASA video recording closely showing the breakup and the subsequent remote detonation of one of the booster rockets.[137]
a video recording by Jack Moss from the front yard of his house in Winter Haven, Florida, 80 miles (130km) from Cape Canaveral[138]
a video recording by Ishbel and Hugh Searle on a plane leaving from Orlando International Airport, 50 miles (80km) from Cape Canaveral, was posted by their daughter Victoria Searle on January 30, 2011 along with an interview taken on the couple two days earlier.[139]
a Super 8 mm film recorded by then-19-year-old Jeffrey Ault of Orange City, Florida, at the Kennedy Space Center, 10 miles (16km) from the launch[140]
a video recording by Lawrence Hebert of Electric Sky Films, filmed at the Kennedy Space Center 10 miles from the launch, uncovered in March 2012[141]
a video recording by Steven Virostek uncovered in May 2012[142]
a video recording by Michael and Frances VanKulick of Melbourne, Florida was made public in 2014.[143]
Film
An ABC television movie titled Challenger was broadcast on February 24, 1990. It starred Barry Bostwick as Scobee, Brian Kerwin as Smith, Joe Morton as McNair, Keone Young as Onizuka, Julie Fulton as Resnik, Richard Jenkins as Jarvis and Karen Allen as McAuliffe.[144][145][146]
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.[147][148]
Other media
In the Sega Saturn version of the video game The House of the Dead, the words "Challenger, go at throttle up", spoken by Richard O. Covey from the mission control room only seconds before the explosion, can be heard in the soundtrack of Stage 2, several times.[149] History Channel released a documentary titled Days That Shaped America;[150] the first episode was about the disaster and it was aired on 28 January 2018.[151]
See also

Criticism of the Space Shuttle program
Engineering disasters
List of spaceflight-related accidents and incidents
PEPCON disaster

Notes



This article incorporates from websites or documents ofthe National Aeronautics and Space Administration.




Feynman, Richard P. (1986)  (html)
Jensen, Claus. (1996) No Downlink: A Dramatic Narrative about the Challenger Accident and Our Time. New York: Farrar, Straus, Giroux. ISBN0-374-12036-6.
McConnell, Malcolm. (1987) Challenger: A Major Malfunction. Garden City, NY: Doubleday. ISBN0-385-23877-0.

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Vaughan, Diane. (1996) The Challenger Launch Decision: Risky Technology, Culture and Deviance at NASA. Chicago: University of Chicago Press. ISBN0-226-85176-1.
Wallace, Brendan & Ross, Alastair (2006) Beyond Human Error. Florida: CRC Press. ISBN978-0-8493-2718-6



Further reading




 – compiled by 
. The Boston Globe. January 28, 2011.
 AmericanRhetoric.com
 – video of shuttle launch and Reagan's address – YouTube
, An Emmy Award-winning documentary about flight STS-51-L and what caused the Challenger explosion




CBS Radio news Bulletin of the Challenger Disaster anchored by Christopher Glenn from January 28, 1986
 (mp3),
 (mp3),
 (mp3),
 (mp3).
 – NPR (January 28 and 29, 2016)
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