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
Bill Nelson active duty from 1968 to 1970, attaining the rank of captain, and he remained in the Army until 1971. Nelson was admitted to the Florida bar in 1968, and began practicing law in Melbourne in 1970. In 1971, he worked as legislative assistant to Governor Reubin Askew. In 1972, Nelson married Grace Cavert. The couple have two adult children: Charles William "Bill Jr." Nelson and Nan Ellen Nelson. In 1986, Nelson became the second sitting member of Congress (and the first member of the House) to travel into space. He went through NASA training with Senator Jake Garn of Utah.