Space Shuttle Challenger Crew
Flight of the space shuttle challenger on mission 51L, the 25th flight of the space shuttle program began at 11:38 AM eastern standard time on January 28, 1986, it ended 73 seconds later in a structural breakup of the external tank and orbiter, in which the 7 crew members perished.
The Start (Building The Rocket Ship)[]
The delivery and assembly of 51l launch vehicle components began months prior to launch. The solid rocket booster segments were transported by rail to the Kennedy Space Center. The SRB's were inspected and partially assembled at the rotation, processing, and storage facility. The segments were then moved to the vehicle assembly building or VAB where they were stacked on the mobile launch platform. The external tank arrived at KSC by Barge, and was moved into the VAB where it was checked out and mated with the stacked solid rocket boosters. After orbiter checkout, challenger was rolled into the VAB, and mated with the assembled external tank and SRB's. The STS-51L vehicle was transported from the VAB to the launch pad on December 22, 1985. At a crawler speed at approximately 1 MPH, the journey takes about six hours. The launch was rescheduled several times, resulting in the final countdown on January 28, 1986. The weather was forecast to be clear and cold with temperatures dropping into the low 20s overnight. The fueling of the external tank began at 1:25 AM. Ice had accumulated on the launch pad during the night, several water systems were opened slightly and allowed to flow into drains, the drains froze and caused overflows, high wind gusts spread water over large areas and ice formed. The air temperature at launch was 35 degrees fahrenheit, this was 15 degrees colder than any previous launch.
The crew of Space Shuttle Challenger consisted of 7 people.
- Francis R. Scobee - Mission Commander - Michael J. Smith - Pilot - Gregory B. Jarvis - Payload Specialist 1 - Christa McAuliffe - Payload Specialist 2 - Judith A. Resnik - Mission Specialist 1 - Ellison S. Onizuka - Mission Specialist 2 - Ronald E. McNair - Mission Specialist 3
The Challenger cargo included two satellites in the cargo bay and equipment in the crew compartment for experiments that would be carried out during the mission. The payloads flown on Space Shuttle Challenger Mission 51-L included:
- Tracking Data Relay Satellite-2 (TDRS-2): a NASA communications satellite that was to have been placed in a geosynchronous orbit with the aid of a booster called the Inertial Upper Stage. The satellite would have supported communications with the Space Shuttle and up to 23 other spacecraft.
- Spartan satellite that would be deployed into orbit carrying special instruments for the observation of Halley's Comet. Spartan satellite was to have been deployed into low Earth orbit using the remote manipulator system. Halley's Comet Experiment Deployable, a free-flying module designed to observe tail and coma of Halleys comet with two ultraviolet spectrometers and two cameras.
The Lift-off[]
At t-minus 7 minutes and 30 seconds, the ground launch sequencer began retracting the crew access arm, the arm can be put back in place within 15 to 20 seconds if an emergency arises and the crew must evacuate the pad. At t-minus 3 minutes and 15 seconds, gimbal checks of the orbiter main engines were performed, all three engines move in a pre-programmed pattern to verify ascent flight control. The gimbal sequence ends with the engines with their start positions. At t-minus 2 minutes and 55 seconds, external tank liquid oxygen pressurization began and main engine purging was completed, at t-minus 2 minutes and 50 seconds, retraction of the gaseous oxygen vent hood began. The ground launch sequencer verified its full retraction at t-minus 37 seconds. Sound suppression water was started at t-minus 16 seconds. At t-minus 8 seconds, hydrogen igniters were turned on to burn off any free hydrogen. 6.6 seconds before launch, challengers liquid-fueled main engines were ignited in sequence, and run up to full thrust. Thrust from the main engines bends the shuttle stack, when it returned at vertical, the Solid Rocket Boosters ignited. At t-minus 0, the hold down bolts were explosively released. After the initial pre-release twang motion, structural forces on the assembly dissipated through vibration at a rate of three cycles per second during the first few seconds of flight. Roll maneuver was initiated at 7.724 seconds. The maneuver was completed at 21.124 seconds. The main engines were throttled back to 65 percent at 35.379 seconds for about 16 seconds in order to alleviate loads during maximum dynamic pressure. The engines were then throttled up to 104 percent at 51.919 seconds. During the flight, telemetry data gave no indication of problems. The solid rocket boosters continued in flight, and were destroyed by the range safety officer 110 seconds after launch.
Postflight Analyses[]
There was a graphic indicating 3 viewing angles at the vicinity of the launch pad. We now go to camera E-63 at the lower right of the chart. At .678 seconds during the flight, a strong puff of gray smoke can be seen spurting from the vicinity of the aft field joint on the right rocket solid booster. The vaporized material streaming from the joint indicates there was not complete sealing action within the joint. This second view is from camera E-60. The smoke can be seen between the right SRB and External Tank and initially moves in the upward direction. The angle between this view and E-63 is approximately 100 degrees. With E-60 & E-63 side by side, it is clear that when smoke is first visible to camera E-60, it is not visible to E-63, .2 seconds later, it is visible to E-63.
Space Shuttle Challenger exploding
thumb|300px|right|Challenger Disaster
Orbiter Did not explode[]
Challenger itself did not explode, but various structural failures caused the orbiter to break apart. Although the Challenger disintegrated almost without warning, the crew may have briefly been aware that something was wrong. The crew cabin tore lose from the rest of the shuttle and soared through the air. It took almost three minutes for the cabin to fall into the Atlantic Ocean, where it smashed on impact, killing the seven crew members.
Space Shuttle SRB's[]
A full year before Challenger was launched, a major fault was discovered in the design of the solid rocket boosters - the SRB's. These 2 immensely powerful rockets are strapped to the side of the External Tank and accelerate the shuttle clear of the Earth's atmosphere. 2 minutes after launch, the SRB's release from the Shuttle, dropping to the ocean and are collected for reuse. The SRB's were built for NASA by a contractor, Morton Thiokol, Inc.
Shuttle Aftermath[]
All shuttle missions were halted while a special commission appointed by President Reagan determined the cause of the accident and what could be done to prevent such disasters from happening again. It was headed by former secretary of state William Rogers the commission included former astronaut Neil Armstrong and former test pilot Chuck Yeager.
Shuttle Investigation[]
In June 1986, the commission reported that the accident was caused by a failure of O rings in the shuttle's right solid rocket booster. These rubber rings sealed the joint between the two lower segments of the booster. Design flaws in the joint and unusually cold weather during the launch caused the O rings to allow hot gases to leak out of the booster through the joint. Flames from within the booster streamed past the failed seal and quickly expanded the small hole. The flaming gases then burned a hole in the shuttle's external fuel tank. The flames also cut away one of the supporting beams that held the booster to the side of the external tank. The booster tore loose and ruptured the tank. The propellants from the tank formed a giant fireball as structural failures tore the vehicle apart.
The commission said NASA's decision to launch the shuttle was flawed. Top level decision makers had not been informed of problems with the joints and O rings or the possible damaging effects of cold weather. The Commission also concluded that there was a serious flaw in the decision making process leading up to the launch of flight 51-L.
Resuming[]
Shuttle Modifications[]
Shuttle designers made several technical modifications, including an improved O ring design and the addition of a crew bail-out system. Although such a system would not work in all cases, it could save lives of shuttle crew members in certain situations. Procedural changes included stricter safety reviews and more restrictive launching conditions.
Shuttle resumes flight[]
The entire space shuttle program was grounded during the commission's investigation and did not resume flying until shuttle designers made several technical modifications and NASA management implemented stricter regulations regarding quality control and safety. The space shuttle resumed flying on September 29, 1988 with the launch of the redesigned shuttle Discovery on STS-26 mission. In 1991, the shuttle Endeavour joined the fleet to replace the Challenger, again bringing the number of ships to four. All above information came from http://www.aerospaceguide.net/spaceshuttle/challenger_disaster.html
Local newspaper coverage
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