Shuttle-C

thumb|right|An artist's conception of a Shuttle-C launching at night thumb|Shuttle-C in space with its cargo bay doors open The Shuttle-C was a study by NASA to turn the Space Shuttle launch stack into a dedicated uncrewed cargo launcher. The Space Shuttle external tank and Space Shuttle Solid Rocket Boosters (SRBs) would be combined with a cargo module to take the place of the Shuttle orbiter and include the main engines. Various Shuttle-C concepts were investigated between 1984 and 1995.

The Shuttle-C concept would theoretically cut development costs for a heavy launch vehicle by re-using technology developed for the shuttle program. End-of-life and Space Shuttle hardware would also have been used. One proposal even involved converting Columbia or Enterprise into a single-use cargo launcher. Before the loss of Space Shuttle Challenger, NASA had expected about 24 shuttle flights a year. In the aftermath of the Challenger incident, it became clear that this launch rate was not feasible for a variety of reasons. With the Shuttle-C, it was thought that the lower maintenance and safety requirements for the uncrewed vehicle would allow a higher flight rate. thumb|Shuttle-C with ILREC Piloted Lander (launch shroud not visible) The Shuttle-C would have been the main crew launch vehicle for the ILREC Piloted Lander in the International Lunar Resources Exploration Program.