Russell Schweickart served as lunar module pilot for the flight of Apollo 9.
The crew of Apollo 9 demonstrated support facilities for the crew, the spacecraft, and the mission during this Earth orbital flight, with a total of 152 orbits, in preparation for a manned lunar landing flight. It was the first manned flight to use all lunar hardware in Earth orbit, including the Lunar Excursion Module, LEM.
The crew also demonstrated their performance with the LEM. The Apollo 9 astronauts performed selected lunar orbit rendezvous mission activities including transposition, intervehicular crew transfer, and LEM active rendezvous and docking.
They tested human reactions to space and weightlessness.