STS-38 was the seventh dedicated Department of Defense mission. Primary payloads on this flight were classified.
Life Sciences experiments performed 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 Atlantis was originally set to land on November 19, but was delayed one day due to unacceptable weather conditions at the planned landing site, Edwards Air Force Base. The location was changed and Atlantis, and its crew touched down at KSC on November 20, 1990.