This program began after the conclusion of the Apollo and Skylab programs, with the first prototype launched in 1977 functioning solely as a glider. The orbiter Columbia flew the first official mission in 1981, and the final mission of this program, Atlantis, launched in 2011. Despite its achievements, this program faced tragedies with the loss of Challenger in 1986 and Columbia in 2003. For 10 points, name this NASA program with orbiters named Discovery and Endeavour.
a) Mercury Program
b) Apollo Program
c) Space Shuttle Program
d) Skylab Program