STS-61-A was the 22nd mission of NASA's Space Shuttle program. It was a scientific Spacelab mission, funded and directed by West Germany – hence the non-NASA designation of D-1. STS-61-A was the ninth and last successful flight of Space Shuttle Challenger before the STS-51-L disaster. STS-61-A holds the current record for the largest crew—eight people—aboard any single spacecraft for the entire period from launch to landing.