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 display cases with shuttle program artifacts. On August 14, 2014, a heavy lift was completed to place "Independence" on top of NASA 905, which had been moved to Space Center Houston from Ellington Field on April 30, 2014. The combined exhibit, named "Independence Plaza", opened to the public on January 23, 2016, at an estimated cost of . Space Shuttle Independence Space Shuttle "Independence, formerly known as Explorer", is a full-scale, high-fidelity replica of the Space Shuttle. It was built by Guard-Lee in Apopka, Florida, installed at Kennedy Space Center Visitor Complex in 1993, and moved to Space Center Houston