John W. Young was originally assigned to command this mission,[2] which would have been his seventh spaceflight, but was reassigned to an administrative position and was replaced by Loren J. Shriver in 1988.

On launch day, the countdown was briefly halted at T−31 seconds when Discovery's computers failed to shut down a fuel valve line on ground support equipment.

It was designed to operate above the Earth's turbulent and obscuring atmosphere to observe celestial objects at ultraviolet, visible and near-infrared wavelengths.

Discovery's reentry from its higher-than-usual orbit required a deorbit burn of 4 minutes and 58 seconds, the longest in Shuttle history up to that time.

The array eventually came free and unfurled through ground control while McCandless and Sullivan were pre-breathing inside the partially depressurized airlock.

Also included were the Ascent Particle Monitor (APM) to detect particulate matter in the payload bay; a Protein Crystal Growth (PCG) experiment to provide data on growing protein crystals in microgravity, Radiation Monitoring Equipment III (RME III) to measure gamma ray levels in the crew cabin; Investigations into Polymer Membrane Processing (IPMP) to determine porosity control in the microgravity environment, and an Air Force Maui Optical Site (AMOS) experiment.

[8] The mission marked the 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 (IDRD) experiment.

[11] NASA began a tradition of playing music to astronauts during the Project Gemini, which was first used to wake up a flight crew during Apollo 15.