Bluford also served on the crew of STS-39, which launched from Kennedy Space Center on April 28, 1991, aboard the Orbiter "Discovery". The crew gathered aurora, Earth-limb, celestial, and Shuttle environment data with the AFP-675 payload. This payload consisted of the Cryogenic Infrared Radiance Instrumentation for Shuttle (CIRRIS-1A) experiment, Far Ultraviolet Camera experiment (FAR UV), the Uniformly Redundant Array (URA), the Quadrupole Ion Neutral Mass Spectrometer (QINMS), and the Horizon Ultraviolet Program (HUP) experiment. The crew also deployed and retrieved the SPAS-II which carried the Infrared Background Signature Survey (IBSS) experiment. The crew also operated the Space Test Payload-1 (STP-1) and deployed a classified payload from the Multi-Purpose Experiment Canister (MPEC). After completing 134 orbits of the Earth and 199 hours in space, "Discovery" landed at the Kennedy Space Center on May 6, 1991.