The Apollo Lunar Module (LEM, LM) was a two-stage vehicle designed by Grumman Corporation for the National Aeronautics and Space Administration (NASA) to ferry two astronauts from lunar orbit to the lunar surface and back. The upper ascent stage consisted of a pressurized crew compartment, equipment areas, and an ascent rocket engine. The lower descent stage had landing gear and contained the descent rocket engine and lunar surface experiments. Six such craft successfully landed on the Moon between 1969-1972. Willis H. Leonard was a senior structural test engineer for Grumman on this project.