Launch from Cape Canaveral (KSC); landing on Edwards AFB. Launch scheduled for April 18, 1990, then April 12, then April 10, 1990, following Flight Readiness Review (FRR). First time date set at FRR was earlier than that shown on previous planning schedules. Launch April 10, 1990 scrubbed at T-4 minutes due to faulty valve in auxiliary power unit (APU) number one. APU replaced and payload batteries recharged. Countdown briefly halted at T-31 seconds when computer software failed to shut down a fuel valve line on ground support equipment. Engineers ordered valve to shut and countdown continued.

Primary payload Hubble Space Telescope, deployed in a 380-statute-mile orbit; several secondary payloads: (ICBC, APM, AMOS Protein Crystal Growth (PCG) and more). The later very successful Hubble Telescope did not work well, because of mirror-problems; therefore a repair-mission was planned (STS-61).

The record height (needed to deploy Hubble) permitted the crew to photograph earth's large scale geographic features not apparent from lower orbits. Motion pictures were recorded by two IMAX cameras, and the results appeared in the IMAX film Destiny in Space. Experiment activity included a biomedical technology study, advanced materials research; particle contamination and ionizing radiation measurements; and student science project studying zero gravity effects on electronic arcs.