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 Discovery Mercury astronaut John Glenn, who was 77 at the time, flew with "Discovery" on STS-95 in 1998, making him the oldest person to go into space. Had plans to launch United States Department of Defense payloads from Vandenberg Air Force Base gone ahead, "Discovery" would have become the dedicated US Air Force shuttle. Its first West Coast mission, STS-62-A, was scheduled for 1986, but canceled in the aftermath of "Challenger". "Discovery" was retired after completing its final mission, STS 133 on March 9, 2011. The spacecraft is now on display in Virginia at the Steven F. Udvar-Hazy Center, an annex