The lunar module (LM) was the part of the Apollo spacecraft that carried Apollo astronauts down to the Moon's surface. Its relatively flimsy aluminium construction was made possible by the low lunar gravity (only one-sixth Earth's). Its odd-looking design was a functional one - there was no need for streamlining because it flew only in airless space. The LM was made up of two parts: the lower, descent module and the upper, ascent module. Each had its own rocket engine. The astronauts entered the ascent module from the CSM through a docking hatch. Another hatch opened onto a platform for lunar EVA. The descent module's engine was used for retrobraking as the LM descended to the lunar surface. Four landing legs, fitted with shock absorbers cushioned the touchdown. After lunar EVA, the astronauts lifted off in the ascent stage, using the descent stage as a launch pad. The astronauts rendezvoused with the CSM in lunar orbit, transferred to it, and then jettisoned the LM.
