STS-33 was the fifth dedicated Department of Defense mission. Primary payloads on this flight were classified. Among the non-classified activities was the retrieval of the Long Duration Exposure Facility (LDEF), a non-powered space vehicle containing experiments, which was deployed during the STS-41C Shuttle mission.
Life Sciences experiments on this mission included multiple Detailed Supplementary Objectives (DSOs). A DSO is a NASA-sponsored investigation performed by Space Shuttle crewmembers, who serve as the test subjects. These studies required minimal crew time, power and stowage. Biomedical DSOs focus on operational concerns, including space motion sickness, cardiovascular deconditioning, muscle loss, changes in coordination and balance strategies, radiation exposure, pharmacokinetics and changes in the body's biochemistry.
The Shuttle was scheduled to land at Edwards Air Force Base on November 26, but was postponed one day due to strong winds at the landing site. Discovery touched down at Edwards Air Force Base on November 27, 1989. The total duration of the mission was five days, zero hours, and six minutes.