The term 'moon lander' refers to the Apollo Lunar MODULE (LEM), a spacecraft designed by the United States for the Apollo program to carry two astronauts from lunar orbit to the surface of the Moon and back. The LEM was composed of two parts: the descent MODULE, which housed the crew and equipment during landing, and the ascent MODULE, which provided propulsion for the return trip to lunar orbit. The LEM was the first manned spacecraft to land on the Moon and was used in all six Apollo missions that landed on the Moon. The LEM was also known as the Lunar Excursion MODULE (MODULE).