"This program began after the conclusion of the Apollo and Skylab programs, and was intended for as many as 50 missions a year. The first prototype of this program was launched in 1977 from the back of a 747 and functioned solely as a glider. The first official mission of this program was flown by the orbiter Columbia in 1981, and the final mission of this program, Atlantis, was
launched in 2011. This program lost two craft during its duration, Challenger in 1986, and Columbia in 2003. For 10 points, name this NASA program which had orbiters named Discovery and Endeavour."
A) Apollo
B) Skylab
C) Space Shuttle
D) Gemini