The primary payload on STS-34 was the Galileo/Jupiter spacecraft and attached Inertial Upper Stage (IUS) deployed six hours and 30 minutes into flight. IUS stages fired, placing Galileo on trajectory for a six-year trip to Jupiter. The STS-34 crewmembers were Commander Donald E. Williams, Pilot Michael J. McCulley, and Mission Specialists Franklin R. Chang-Diaz, Shannon W. Lucid, and Ellen S. Baker.
Life sciences payloads included the Growth Hormone Concentration and Distribution (GHCD). The objective of the GHCD experiment was to characterize the effect of microgravity on indoleacetic acid, a plant growth hormone. Ground studies had established that a gravitational stimulus causes rapid hormonal changes in the plant. As indoleacetic acid concentration increases in the lower part of the stem, the stem reorients and grows upward. An understanding of this effect was expected to lead to finding the gravity-detecting device in the plants.
Detailed Supplementary Objectives (DSOs) were also performed on this mission. ADSO is a NASA-sponsored investigation that is performed by Space Shuttle crewmembers, who also 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.
Additional payloads included Shuttle Solar Backscatter Ultraviolet experiment, Polymer Morphology experiment, Sensor Technology experiment, Mesoscale Lightning Experiment, Air Force Maui Optical Site experiment, IMAX camera and a Shuttle Student Involvement Program experiment that investigated ice crystal formation in zero gravity.
Space Shuttle Atlantis landed on October 23, 1989, at Edwards Air Force Base in California after a successful five-day mission.