The primary payload was the United States Microgravity Laboratory-I (USML-1), a manned Spacelab module with a connecting tunnel to the orbiter crew compartment. USML-1 was a national effort to advance microgravity research in a broad number of disciplines. The 13 day mission, the first Extended Duration Orbiter flight and the longest space shuttle mission to date, also provided new information on the effects of long-term human stay in space. Experiments conducted were: Crystal Growth Furnace (CGF), Drop Physics Module (DPM), Surface Tension Driven Convection Experiment (STDCE), Zeolite Crystal Growth (ZCG), Protein Crystal Growth (PCG), Glovebox Facility (GBX), Space Acceleration Measurement System (SAMS), Generic Bioprocessing Apparatus (GBA), Astroculture-1 (ASC), Extended Duration Orbiter Medical Project (EDOMP), and Solid Surface Combustion Experiment (SSCE).
Secondary experiments included Investigation in Polymer Membrane Processing (IPMP), Shuttle Amateur Radio Experiment II (SAREX-II), and Ultraviolet Plume Instrument (UVPI).