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 Columbia disaster crew of two. Less than a year after the accident, President Bush announced the Vision for Space Exploration, calling for the space shuttle fleet to complete the ISS, with retirement by the year 2010 following the completion of the ISS, to be replaced by a newly developed Crew Exploration Vehicle for travel to the Moon and Mars. NASA planned to return the space shuttle to service around September 2004; that date was pushed back to July 2005. On July 26, 2005, at 10:39 am EST, Space Shuttle "Discovery" cleared the tower on the "Return to Flight" mission STS-114, marking the