Space Shuttle Challenger disaster



The first Space Shuttle Disaster was Challenger which was lost during an explosion as it took off from Cape Canaveral on January 28, 1986, killing all seven people on board. NASA suspended shuttle flights for two years.

The Space Shuttle Challenger Mission (Flight STS-51L) was the 25th Space Shuttle mission and the 10th launch of the Space Shuttle Challenger.

It was launched from Pad 39B at Kennedy Space Center in Florida at 11:38am EST. This mission was highly publicized because it was the first time a school teacher was allowed to travel in space. Christa McAuliffe, a high school teacher from New Hampshire was to be the the first civilian in space. She was selected from  more than 11,000 applicants.

The crew of Space Shuttle Challenger consisted of 7 astronauts:

- 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.

Space Shuttle Challenger Mission 51 L History

Shuttle Mission 51-L was originally scheduled for July, 1985. The astronaut crew were assigned in January 1985, however, the launch was rescheduled to late November 1985 due to changes in payloads. The November launch date slipped due to delays.

The launch was re-scheduled for January 22, however, the date slipped to January 23, then January 24, due to delays in mission 61-C. Launch was reset for January 25 because of bad weather at the transoceanic abort landing (TAL) site in Dakar, Senegal. To utilize Casablanca (not equipped for night landings) as alternate TAL site, T-zero was moved to a morning lift-off time. The launch was postponed another day when launch processing was unable to meet the new morning lift-off time. Prediction of unacceptable weather at the Kennedy Space Center (KSC) led to the launch being rescheduled for 9:37 a.m. EST, January 27.

The launch was delayed 24 hours again when the ground servicing equipment hatch closing fixture could not be removed from the orbiter hatch. The fixture was sawed off and an attaching bolt drilled out before closeout was completed. During the delay, cross winds exceeded return-to-launch-site limits at KSC's Shuttle Landing Facility. The launch on January 28 was delayed two hours when a hardware interface module in the launch processing system, which monitors the fire detection system, failed during liquid hydrogen tanking procedures.

After several launch delays, NASA officials overruled the concerns of the engineers and ordered a lift off on a cold morning, at 11:38:00 a.m. EST on January 28, 1986. The mission ended in tragedy. Challenger disintegrated into a ball of fire. The accident occurred 73 seconds into flight, at an altitude of 46,000 feet (14, 020 meters) and at about twice the speed of sound.

Cause of the Disaster

The main cause of the explosion was the failure of the aft joint seal in the right SRB due to the cold weather. A combustion gas leak through the right Solid Rocket Motor aft field joint initiated at or shortly after ignition eventually weakened and/or penetrated the External Tank initiating vehicle structural break-up and loss of the Space Shuttle Challenger during STS Mission 51-L.

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.

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.