The primary payload was the third and final component of the Tracking and Data Relay Satellite (TDRS) constellation in geosynchronous orbit. The three on-orbit satellites were stationed over the equator at about 22,300 miles above Earth; two of them 130 degrees apart and a third located between them as an on-orbit spare.
On Flight Day 1, one of three cryogenic hydrogen tanks which supply the fuel cells that produce electricity exhibited erratic pressure fluctuations. It was deactivated while engineers studied the problem, and the crew was told to conserve electrical power. The tank was reactivated on Flight Day 3, March 15, and operated successfully.
Landing occurred March 18, 1989, on orbit 80, one orbit earlier than planned, in order to avoid possible excessive wind buildup expected at the landing site. Touchdown was on Runway 22 at Edwards AFB, CA, at 9:35 a.m. EST. Total mission elapsed time was 4 days, 23 hours, and 39 minutes.
Payload and Experiments. The Tracking and Data Relay Satellite (TDRS-D), which became TDRS-4 in space, and its attached Inertial Upper Stage (IUS), were deployed from the payload bay less than six hours after launch, at 3:12 a.m. EST. First-stage orbit burn of the IUS took place an hour later, and the second burn to circularize the orbit occurred at 12 hours, 30 minutes, mission elapsed time. It was stationed at 41 degrees west longitude.
There were eight secondary payloads, including two Shuttle Student Involvement Program experiments. One student experiment, using four live rats with tiny pieces of bone removed, was to test whether the environmental effects of space flight inhibit bone healing. The other student experiment was to fly 32 chicken eggs to determine the effects of space flight on fertilized chicken embryos.
One experiment, mounted in the payload bay, was only termed "partially successful." The Space Station Heat Pipe Advanced Radiator Element, a potential cooling system for Space Station Freedom, operated continuously for less than 30 minutes under powered electrical loads. The failure was blamed on faulty design of the equipment, especially the manifold section.
All other experiments operated successfully. Crystals were obtained from all the proteins in the Protein Crystal Growth experiment. The Chromosomes and Plant Cell Division in Space (CHROMEX), a life sciences experiment, was designed to show the effects of microgravity on root development. The IMAX (70 mm) camera was used to film a variety of scenes, including the effects of floods, hurricanes, fires and volcanic eruptions on Earth.
Primary payload, Tracking and Data Relay Satellite-4 (TDRS-4) attached to an Inertial Upper Stage (IUS), became third TDRS deployed. After deployment, IUS propelled satellite to geosynchronous orbit. Secondary payloads: Orbiter Experiments Autonomous Supporting Instrumentation System-1 (OASIS-1); Space Station Heat Pipe Advanced Radiator Experiment (SHARE); Protein Crystal Growth (PCG); Chromosomes and Plant Cell Division (CHROMEX); two Shuttle Student Involvement Program (SSIP) experiments; and Air Force experiment using orbiter as calibration target for ground-based experiment for Air Force Maui Optical Site (AMOS) in Hawaii. Crew also photographed Earth with a hand-held IMAX camera.