The Apollo Vehicle, briefly referred to as the Lunar Excursion Module (LEM), was a spacecraft used by the United States during the Apollo program for lunar landings. It was designed and built by Grumman Aircraft Engineering Corporation and was the first crewed spacecraft to land on the Moon. The LEM was a two-stage vehicle, consisting of an ascent stage and a descent stage. The ascent stage was used to return the astronauts from the lunar surface to the command module in lunar orbit. The descent stage was used to carry the astronauts from the command module to the lunar surface and back.