Apollo Lunar Module

The Apollo Lunar Module (LM), also known as the Lunar Excursion Module (LEM), 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 (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. 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.

Its development was also plagued with several hurdles which delayed its first unmanned flight by about ten months, and its first manned flight by about three months. Despite this, 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 (Apollo 13's LM-7 Aquarius) greatly exceeded its design requirements by maintaining life support for astronauts after an explosion damaged the Apollo Service Module.