The Apollo Lunar Module was the lander portion of the Apollo spacecraft built for the US Apollo program by Grumman to achieve the transit from lunar orbit to the surface and back. The module was also known as the LM from the manufacturer designation (often pronounced "lem," from NASA's early name for it, Lunar Excursion Module).The module was designed to carry a crew of two and rested on four landing legs. It consisted of two stages, the descent stage and the ascent stage. The total mass of the module was 15,264 kg, with the majority (10,334 kg) in the descent stage. 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.