Schweickart flew as Lunar Module Pilot on Apollo 9, the first crewed flight of the complete Apollo spacecraft in Earth orbit. With James McDivitt and David Scott, he helped test the lunar module, docking procedures, rendezvous — open definition operations, and spacesuit systems that had to work before NASA could attempt a lunar landing. His EVA — open definition tested the portable life support system that later Moonwalkers would depend on.

Illness limited some of Schweickart's planned EVA work, but Apollo 9 still proved the lunar module could operate with a crew. After Apollo, he worked on Skylab backup and rescue planning, then moved into technology, government, and public-interest work. He later co-founded the B612 Foundation, advocating for detection and prevention of asteroid impact hazards.

Schweickart's background fit the broader pattern of the early astronaut corps: technical training, operational discipline, and a career built around difficult work before spaceflight. His formal education included Massachusetts Institute of Technology (B.S. Aeronautical Engineering, 1956), and Massachusetts Institute of Technology (M.S. Aeronautics and Astronautics, 1963). His service background is recorded as United States Air Force and Massachusetts Air National Guard, Fighter pilot and engineer before NASA selection. His personal record also sits alongside a family life recorded as two marriages, four children, a reminder that these careers unfolded within ordinary lives as well as national history.

Schweickart's flown space career centered on Apollo 9, where he served as Lunar Module Pilot. First crewed flight of the complete Apollo spacecraft: command module, service module — open definition, and lunar module. The crew tested lunar module operations, docking, rendezvous, and a spacesuit-supported EVA in Earth orbit. The EVA record adds another layer to the mission: About 1 hour, 17 minutes outside the lunar module during Apollo 9 spacesuit and EVA testing.