Following Apollo 8’s successful orbit of the Moon late in 1968, the next mission linked the Command/Service Module (CSM) and Lunar Module (LM) together as a complete Apollo system. The LM had not been ready in time for the preceding flight, but on 3 March 1969 it took off on a ten-day low Earth orbit, propelled into space by a Saturn V SA-504 rocket booster. The mission was significant in that it was the first manned flight of an LM, the first docking took place and it featured the first two-man spacewalk. The mission was able to test various procedures, backpack life support systems, docking manoeuvers & the LM engines in preparation for the eventual Moon landing of Apollo 11. Apollo 9 thus proved that orbital rendezvous was feasible, something essential for a Moon landing.