Description & Facts: "Crew and Challenger Tribute" Space Shuttle Challenger (NASA Orbiter Vehicle Designation: OV-099) was NASA's second Space Shuttle orbiter to be put into service, Columbia being the first. 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. (For more on the Challenger disaster, see Space Shuttle Challenger disaster.) 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 1992. History Challenger was named after HMS Challenger, a British corvette which carried out a pioneering global marine research expedition in the 1870s. Construction Because of the low production of Orbiters, the Space Shuttle program decided to build a vehicle as a Static Test Article, STA-099, that could later be converted to a flight vehicle. 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. NASA planned to refit the prototype orbiter Enterprise (OV-101), used for flight testing, as the second operational