The primary payload on this flight was classified.
Non-classified life sciences experiments performed during the STS-28 mission were those classified as Detailed Supplementary Objectives (DSOs). A DSO is a NASA-sponsored investigation performed by Space Shuttle crewmembers, who serve as the test subjects. These studies are designed to require 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.
During the flight, the crew shut down a thruster in the reaction control system (RCS) because of indications of a leak. Also, a RCS heater malfunctioned.
The Shuttle Atlantis landed at Edwards Air Force Base on August 13, 1989.