The NASA Lunar Module was designed to land two astronauts on the moon and then launch them from its surface. It consisted of two main sections: the lower Descent Stage, which had landing gear, propellant tanks, and a descent engine that could be throttled for a soft landing, and the upper ascent stage, which served as the crew compartment and contained thrusters, a computer, and controls for maneuvering the vehicle. When it was time to return to Earth, both astronauts climbed the ladder and reentered the LM, and the descent stage then served as the launch pad for the ascent stage, which carried the astronauts and lunar samples to a rendezvous with the waiting Command Module. Because there was no air on the moon, the LM was not aerodynamically streamlined. With its legs folded, the Lunar Module was stored inside the cone-shaped Lunar Module Spacecraft Adapter of the Saturn V.