The
Apollo Lunar Module (
LM), originally designated the
Lunar Excursion Module (
LEM), was the
lander portion of the
Apollo spacecraft built for the
US Apollo program by
Grumman Aircraft to carry a crew of two from lunar orbit to the surface and back. Designed for
lunar orbit rendezvous, it consisted of an ascent stage and descent stage, and was ferried to lunar orbit by its companion
Command and Service Module (CSM), a separate spacecraft of approximately twice its mass, which also took the astronauts home to Earth. After completing its mission, the LM was discarded. It was capable of operation only in outer space; structurally and aerodynamically it was incapable of flight through the Earth's atmosphere. The Lunar Module was the first, and to date only, manned spacecraft to operate exclusively in the airless vacuum of space.