THE SPACECRAFT
 
          Apollo was a three-part spacecraft: the command
module (CM), the crew's quarters and flight control section;
the service module (SM) for the propulsion and spacecraft
support systems (when together, the two modules are called
CSM); and the lunar module (LM), to take two of the crew to
the lunar surface, support them on the Moon, and return them
to the CSM in lunar orbit.
 
          The flight mode, lunar orbit rendezvous, was
selected in 1962. The boosters for the program were the
Saturn IB for Earth orbit flights and the Saturn V for lunar
flights.