Apollo 9 tested the lunar module in Earth orbit before crewed lunar operations began.
Launched on March 3, 1969, Apollo 9 carried James McDivitt, David Scott, and Rusty Schweickart. It was the first crewed flight of a complete Apollo spacecraft with both the command-service module and lunar module. The crew practiced docking, undocking, propulsion burns, and life-support operations.
The lunar module was named Spider, while the command module was called Gumdrop. Schweickart also performed a spacewalk to test the portable life-support system that would support lunar surface activity. Apollo 9’s Earth-orbit tests prepared the hardware for Apollo 10’s lunar-orbit dress rehearsal.