Space Shuttle Challenger

 

Space Shuttle Challenger (NASA Orbiter Vehicle Designation: OV-099) was NASA's second Space Shuttle orbiter to be put into service, Columbia having been the first. The shuttle was built by Rockwell International's Space Transportation Systems Division in Downey, California. Its maiden flight was on April 4, 1983, and it completed nine missions before breaking apart 73 seconds after the launch of its tenth mission, STS-51-L on January 28, 1986, resulting in the death of all seven crew members. It was the first of two shuttles (the other being Columbia) to be destroyed. The accident led to a two-and-a-half year grounding of the shuttle fleet, with missions resuming in 1988 with the launch of Space Shuttle Discovery on STS-26. Challenger itself was replaced by the Space Shuttle Endeavour, which first launched in May 1992 and was constructed from structural spares that had been ordered by NASA as part of the construction contracts for Discovery and Atlantis.

 

History

Challenger was named after HMS Challenger, a British corvette that was the command ship for the Challenger Expedition, a pioneering global marine research expedition undertaken from 1872 through 1876.^[2] The Apollo 17 lunar module that landed on the Moon in 1972 was also named Challenger.^[2]

  Construction

 

Because of the low production of orbiters, the Space Shuttle program decided to build a vehicle as a Structural Test Article, STA-099, that could later be converted to a flight vehicle. The contract for STA-099 was awarded to North American Rockwell on July 26, 1972, and its construction was completed in February 1978.^[3] After STA-099's rollout, it was promptly sent to Lockheed, where it would spend over 11 months in vibration tests designed to simulate entire shuttle flights, from launch to landing.^[4] In order to prevent damage during structural testing, qualification tests were performed to a factor of safety of 1.2 times the design limit loads. The qualification tests were used to validate computational models, and compliance with the required 1.4 factor of safety was shown by analysis.^[5]

NASA planned to refi the prototype orbiter Enterprise (OV-101), used for flight testing, as the second operational orbiter. However, design changes made during construction of the first orbiter, Columbia (OV-102), would have required extensive rework. Because STA-099's qualification testing prevented damage, NASA found that rebuilding STA-099 as OV-099 would be less expensive than refitting Enterprise. Work on converting STA-099 into Challenger began in January 1979, starting with just the crew module as the rest of the orbiter was still used by Lockheed. STA-099 returned to Palmdale in November 1979, and the original crew module was replaced with the newly-constructed model. Work continued on the conversion until 1982.^[6]

Challenger (and the orbiters built after it) had fewer tiles in its Thermal Protection System than Columbia, though it still made heavy use of LRSI tiles on the cabin and main fuselage compared to the later orbiters. Most of the tiles on the payload bay doors, upper wing surfaces, and rear fuselage surfaces were replaced with DuPont white Nomex felt insulation. These modifications as well as an overall lighter structure allowed Challenger to carry 2,500 lb (1,100 kg) more payload than Columbia. Challenger's fuselage and wings were also stronger than Columbia's despite being lighter.^[7] The hatch and vertical stabilizer tile patterns were also different from that of the other orbiters. Challenger was also the first orbiter to have a head-up display system for use in the descent phase of a mission, and the first to feature Phase I main engines rated for 104% maximum thrust.