Space Shuttle gliding and landing; it was originally intended to be outfitted for orbital operations after the test program, but it was found more economical to upgrade the structural test article STA-099 into orbiter "Challenger" (OV-099). An additional test article, dubbed "Pathfinder" (OV-098), was built for form and fit tests, and is on display at the Alabama Space and Rocket Center in Huntsville, AL. "Challenger" disintegrated 73 seconds after launch in 1986, and "Endeavour" was built as a replacement from structural spare components. Building "Endeavour" cost about US$1.7 billion. "Columbia" broke apart over Texas during re-entry in 2003. A Space Shuttle launch
Space Shuttle at Edwards Air Force Base, California, or use one of the multiple alternate landing sites around the world. A landing at any site other than Kennedy Space Center meant that after touchdown the Shuttle must be mated to the Shuttle Carrier Aircraft and returned to Cape Canaveral. Space Shuttle "Columbia" (STS-3) once landed at the White Sands Space Harbor, New Mexico; this was viewed as a last resort as NASA scientists believed that the sand could potentially damage the Shuttle's exterior. There were many alternative landing sites that were never used. An example of technical risk analysis for a STS