The primary task of STS-61-A was to conduct a series of experiments, almost all related to functions in microgravity, in Spacelab D-1, the third flight of a Spacelab orbital laboratory module. Two other mission assignments were to deploy the Global Low Orbiting Message Relay Satellite (GLOMR) out of a Getaway Special canister in the cargo bay, and to operate five materials processing experiments, which were mounted in the orbiter's payload bay on a separate device called the German Unique Support Structure. The experiments included investigations into fluid physics, with experiments in capillarity, Marangoni convection, diffusion phenomena, and critical points; solidification experiments; single crystal growth; composites; biological studies, including cell functions, developmental processes, and the ability of plants to perceive gravity; medical experiments, including the gravitational perceptions of humans, and their adaptation processes in space; and speed-time interaction studies of people working in space.