STS-51-L

STS-51-L was the twenty-fifth flight of the American Space Shuttle program, using Space Shuttle Challenger, which lifted off from the Launch Complex 39-B on 28 January 1986 from Kennedy Space Center in Florida. This flight marked the first time an non-government civilian, schoolteacher Christa McAuliffe, had flown aboard the Space Shuttle. The mission ended in disaster with the destruction of Challenger 73 seconds after lift-off and the death of all seven crewmembers. The Rogers Commission determined the cause was due to the failure of an O-ring seal on one of the Solid Rocket Boosters (SRBs).

Planned mission

The tenth mission for Challenger, STS-51-L was scheduled to deploy the second in a series of Tracking and Data Relay Satellites, carry out the first flight of the Shuttle-Pointed Tool for Astronomy (SPARTAN-203)/Halley's Comet Experiment Deployable in order to observe Halley's Comet, and carry out several lessons from space as part of the Teacher in Space Project and Shuttle Student Involvement Program (SSIP). The flight marked the first American orbital mission to involve in-flight fatalities. It was also the first American human spaceflight mission to launch and fail to reach space; the first such mission in the world had been the Soviet Soyuz 18a mission, in which the two crew members had survived. Gregory Jarvis was originally scheduled to fly on the previous shuttle flight (STS-61-C), but was re-assigned to this flight and replaced by Congressman Bill Nelson.^[1]

Crew

Backup crew

Ascent failure

During the ascent phase, 73 seconds after lift-off, the vehicle experienced a catastrophic structural failure resulting in the loss of crew and vehicle. The Rogers Commission later determined the cause of the accident to have been the failure of an O-ring seal on Challenger's right Solid Rocket Booster (SRB). The failure of the seal allowed a flamethrower-like flare to impinge upon one of two aft SRB attach struts, which eventually failed, freeing the booster to pivot about its remaining attachment points. Subsequently, the forward part of the booster cylinder impacted the external tank (ET) intertank area, leading to a structural failure of the ET—the core structural component of the entire stack. A rapid burning of liberated propellants ensued. With the structural "backbone" of the stack compromised and breaking up, the SRBs flew off on their own, as did the orbiter, which rapidly disintegrated due to overwhelming aerodynamic forces. The launch had been approved despite a predicted ambient temperature of 26 °F (−3 °C), well below the qualification limit of major components such as the SRBs, which had been certified for use only at temperatures above 40 °F (4 °C).^[3] Evidence found in the remnants of the crew cabin showed that several of the emergency air supplies (PEAPs) carried by the astronauts had been manually activated, suggesting that forces experienced inside the cabin during breakup of the orbiter were not inherently fatal, and that at least three crew members were alive and capable of conscious action for some period of time following vehicle breakup. "Tracking reported that the vehicle had exploded and impacted the water in an area approximately located at 28.64 degrees north, 80.28 degrees west", Mission Control, Houston.^[4]

Crew fate

On 7 March, divers from the USS Preserver located what they believed to be the crew cabin on the ocean floor. A subsequent dive the following day confirmed that it was the cabin and that the remains of the crew were still inside.^[5] No official investigations into the Challenger Disaster have concluded for certain the cause of death of the astronauts; however it is almost certain the actual disintegration did not kill the entire crew, as 3 of the 4 PEAPs (personal egress air packs) that were recovered had been manually activated, which would only be done during an emergency or loss of cabin pressure (although whether cabin pressure was lost is still in debate but considered likely). However, the PEAPs do not provide a pressurized air flow and would still have resulted in the astronauts losing consciousness within several seconds.^[6] There were media reports alleging that NASA had a secret tape recording of the crew panicking and on board conversation following the disintegration during the 2 minute 45 second free fall before impacting into the sea east of Florida. This was likely fabricated however and no such recording exists: the crew may have been unconscious from loss of cabin pressure, and the astronauts did not wear individual voice recorders.^[7] Also, any such voice recording facility would have been without power, since the breakup of the orbiter immediately separated the crew compartment from the power-generating fuel cells in the back of the vehicle. However, it is certain that the impact of the shuttle with the sea would have killed any still surviving astronauts on board, though they may have died prior to the impact of other causes.

Mission objectives

• Deployment of Tracking Data Relay Satellite-B (TDRS-B) with an Inertial Upper Stage booster
• Flight of Shuttle-Pointed Tool for Astronomy (SPARTAN-203)/Halley's Comet Experiment Deployable
• Fluid Dynamics Experiment (FDE)
• Comet Halley Active Monitoring Program (CHAMP)
• Phase Partitioning Experiment (PPE)
• Three Shuttle Student Involvement Program (SSIP) experiments
• Two lessons for the Teacher in Space Project (TISP)

None of the mission objectives was accomplished.

Mission parameters

• Mass:
  • Orbiter Liftoff: 121,778 kilograms (268,470 lb)
  • Orbiter Landing: 90,584 kilograms (199,700 lb) (planned)
  • Payload: 21,937 kilograms (48,360 lb)
• Perigee: ~285 kilometres (177 mi) (planned)
• Apogee: ~295 kilometres (183 mi) (planned)
• Inclination: 28.45° (planned)
• Period: ~90.4 min (planned)
• Duration: 73 seconds (6 days 0 hours 34 minutes planned)

Mission insignia

The STS-51-L crew members designed the mission patch seen above to represent their participation in NASA's mission aboard Challenger, depicted launching from Florida and soaring into space to carry out a variety of goals. Among the prescribed duties of the five astronauts and two payload specialists (represented by the seven stars of the US flag) was observation and photography of Halley's Comet, backdropped against the U.S. flag in the insignia. Surnames of the crew members encircle the scene, with the payload specialists being recognized below. Surname of the first teacher in space, Christa McAuliffe, is followed by a symbolic apple.

See also

• STS-51-L Mission timeline
• Space Shuttle Columbia disaster
• Space Shuttle program

References

External links

• Report of the Presidential Commission on the Space Shuttle Challenger Accident