The Apollo Lunar Module (LM) was the lander portion of the Apollo spacecraft built for the US Apollo program by Grumman to carry a crew of two from lunar orbit to the surface and back. Six such craft successfully landed on the Moon between 1969–1972.
The LM, consisting of an Ascent stage and Descent stage, was ferried to lunar orbit by its companion Command/Service Module, a separate spacecraft approximately twice as massive, which took the astronauts home to Earth. After completing its mission, the LM was discarded. In one sense it was the world's first true spacecraft in that it was capable of operation only in outer space, structurally and aerodynamically incapable of flight through the Earth's atmosphere.
Though initially unpopular and plagued with several delays in its development, the LM eventually became the most reliable component of the Apollo/Saturn system, the only one never to suffer any failure that significantly impacted a mission, and in at least one instance (LM-7 Aquarius) greatly exceeded its design requirements.