Space Shuttle landing at Edwards, the orbiter was flown back to the KSC on the Shuttle Carrier Aircraft, a specially modified Boeing 747. The first orbiter, "Enterprise", was built in 1976, used in Approach and Landing Tests and had no orbital capability. Four fully operational orbiters were initially built: "Columbia", "Challenger", "Discovery", and "Atlantis". Of these, two were lost in mission accidents: "Challenger" in 1986 and "Columbia" in 2003, with a total of fourteen astronauts killed. A fifth operational (and sixth in total) orbiter, "Endeavour", was built in 1991 to replace "Challenger". The Space Shuttle was retired from service upon the conclusion
Space Shuttle Independence Space Center outside Houston, Texas. The replica shuttle was stripped of the name "Explorer" as part of the dismantling process. Upon arriving in the Houston area by barge on June 1, 2012, the shuttle was taken to the Johnson Space Center dock on Clear Lake, and preparations were made to move the shuttle to Space Center Houston during the early morning hours. As with Florida, several light poles along NASA Parkway were taken down and trees trimmed back to allow passage. The shuttle was moved by another 144-wheel trailer down the closed highway to the visitor center. Johnson Space Center