[5] The launch was originally set for February 22, 1990, but was postponed repeatedly due to the illness of the crew commander and poor weather conditions.

[2] The first rescheduled launch attempt, set for February 25, 1990, was scrubbed at T−31 seconds due to a range safety computer malfunction.

[13] The mission marked another flight of an 5 kg (11 lb) human skull, which served as the primary element of "Detailed Secondary Objective 469", also known as the "In-flight Radiation Dose Distribution Experiment" (IDRD).

Hundreds of thermo-luminescent dosimeters were mounted in the skull's layers to record radiation levels at multiple depths.

This experiment, which also flew on STS-28 and STS-31, was located in the shuttle's mid-deck lockers on all three flights, recording radiation levels at different orbital inclinations.

About 62 impacts in the shuttle's Thermal Protection System (TPS) tiles were counted by the debris team after the mission.