orbiters were built during the Space Shuttle program. Challenger (OV-099) was the second orbiter constructed after its conversion from a structural test On January 28, 1986, Space Shuttle Challenger broke apart 73 seconds into its flight, killing all seven crew members. The spacecraft disintegrated about 46,000 feet (14 km) above the Atlantic Ocean, off the coast of Cape Canaveral, Florida, at 16:39:13 UTC (11:39:13 a.m. EST, local time at the launch site). It was the first fatal accident involving an American spacecraft while in flight. The missi At T+58.788, a tracking film camera captured the beginnings of a plume near the aft attach strut on the right SRB, right before the vehicle passed through max q at T+59.000. The high aerodynamic forces and wind shear likely broke the unintentional aluminum oxide seal that had replaced eroded O-rings, allowing the flame to burn through the joint. Within one second from when it was first recorded, the plume became well-defined, and the enlarging hole caused a drop in internal pressure in the right SRB. A leak had begun in the liquid hydrogen (LH2) tank of the ET at T+64.660, as indicated by the changing shape of the plume. The SSMEs pivoted to compensate for the booster burn-through, which was creating an unexpected thrust on the vehicle. The pressure in the external LH2 tank began to drop at T+66.764 indicating that the flame had burned from the SRB into the… 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 modul At T+58.788, a tracking film camera captured the beginnings of a plume near the aft attach strut on the right SRB, right before the vehicle passed through max q at T+59.000. The high aerodynamic forces and wind shear likely broke the unintentional aluminum oxide seal that had replaced eroded O-rings, allowing the flame to burn through the joint. Within one second from when it was first recorded, the plume became well-defined, and the enlarging hole caused a drop in internal pressure in the right SRB. A leak had begun in the liquid hydrogen (LH2) tank of the ET at T+64.660, as indicated by the changing shape of the plume. The SSMEs pivoted to compensate for the booster burn-through, which was creating an unexpected thrust on the vehicle. The pressure in the external LH2 tank began to drop at T+66.764 indicating that the flame had burned from the SRB into the tank. The crew and flight controllers made no indication they were aware of the vehicle and flight anomalies. At T+68, the CAPCOM, Richard O. Covey, told the crew, "Challenger, go at throttle up", indicating that the SSMEs had throttled up to 104% thrust. In response to Covey, Scobee said, "Roger, go at throttle up"; this was the last communication from Challenger on the air-to-ground loop. At T+72.284, the right SRB pulled away from the aft strut that attached it to the ET, causing lateral acceleration that was felt by the crew. At the same time, pressure in the LH2 tank began dropping. Pilot Mike Smith said "Uh-oh", which was the last crew comment recorded. At T+73.124, white vapor was seen flowing away from the ET, after which the aft dome of the LH2 tank fell off. The resulting release and ignition of all liquid hydrogen in the tank pushed the LH2 tank forward into the liquid oxygen (LOX) tank with a force equating to roughly 3,000,000 pounds (13 MN), while the right SRB collided with the intertank structure. The failure of the LH2 and LOX tanks resulted in a boiling liquid expanding vapor explosion (BLEVE), with a large part of the liquid evaporating back into gas almost instantly. These events resulted in an abrupt change to the shuttle stack's attitude and direction, which was shrouded from view by the vaporized contents of the now-destroyed ET. As it traveled at Mach 1.92, Challenger took aerodynamic forces it was not designed to withstand and broke into several large pieces: a wing, the (still firing) main engines, the crew cabin and hypergolic fuel leaking from the ruptured reaction control system were among the parts identified exiting the vapor cloud. The disaster unfolded at an altitude of 46,000 feet (14 km). Both SRBs survived the breakup of the 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. Pressurization could have enabled consciousness for the entire fall until impact. The crew cabin hit the ocean surface at 207 mph (333 km/h) approximately 2 minutes and 45 seconds after breakup. The estimated deceleration was 200 g, far exceeding structural limits of the crew compartment or crew survivability levels. The mid-deck floor had not suffered buckling or tearing, as would result from a rapid decompression, but stowed equipment showed damage consistent with decompression, and debris was embedded between the two forward windows that may have caused a loss of pressure. Impact damage to the crew cabin was severe enough that it could not be determined whether the crew cabin had previously been damaged enough to lose pressurization.