Deployed Gamma Ray Observatory (GRO) on flight day three. GRO high-gain antenna failed to deploy on command, manually deployed by Ross and Apt during EVA.
Fifth dedicated Spacelab mission, Spacelab Life Sciences-1, and first dedicated solely to life sciences, using the habitable module. Mission featured most detailed and interrelated physiological measurements in space since 1973-1974 Skylab missions.
Upper Atmosphere Research Satellite (UARS), deployed on the third day of the mission. The 14,500-pound observatory made the most extensive study ever conducted of the Earth's troposphere.
