Spacelab-J—a joint NASA and National Space Development Agency of Japan (NASDA) mission using a crewed Spacelab module—conducted microgravity investigations in materials and life sciences. The international crew, consisting of the first Japanese astronaut to fly aboard the Shuttle, the first African-American woman to fly in space and, contrary to normal NASA policy, the first married couple to fly on the same space mission (Lee and Davis), was divided into red and blue teams for around the clock operations. Spacelab-J included 24 materials science and 20 life sciences experiments, of which 35 were sponsored by NASDA, 7 by NASA and 2 collaborative efforts. The Payload Crew Training Manager was Homer Hickam, who also worked during the mission as a Crew Interface Coordinator to talk to the crew during their science experiments and relay any concerns from the scientists on the ground.

Ever since female space travelers became the norm during the 1980s, NASA instituted rules stipulating that husband/wife couples would not be launched together out of concern over disrupting in-flight morale. However, Mark Lee and Jan Davis had secretly married a few weeks before the launch of STS-47 and NASA was forced to waive this rule as it would not have been possible to cancel the mission or reassign crews at this point.

The first married couple in space created months of speculation and jibes from the media about the possibility of them having sexual relations in orbit, but NASA officials were not amused and vehemently shot down the rumors, noting among other things the lack of privacy in the cramped Shuttle cabin and the physics of zero gravity making intercourse difficult if not impossible. Davis and Lee, who later divorced, refused to answer queries about them engaging in intimate activities during the mission.

Materials science investigations covered such fields as biotechnology, electronic materials, fluid dynamics and transport phenomena, glasses and ceramics, metals and alloys, and acceleration measurements. Life sciences included experiments on human health, cell separation and biology, developmental biology, animal and human physiology and behavior, space radiation, and biological rhythms. Test subjects included the crew, Japanese koi fish (carp), cultured animal and plant cells, chicken embryos, fruit flies, fungi, plant seeds, frogs and frog eggs, and oriental hornets.

Twelve Get Away Special (GAS) canisters (10 with experiments, 2 with ballast) were carried in the payload bay. Middeck experiments were: Israeli Space Agency Investigation About Hornets (ISAIAH), Solid Surface Combustion Experiment (SSCE), Shuttle Amateur Radio Experiment (SAREX II), Air Force Maui Optical Site (AMOS), and Ultraviolet Plume Imager (UVPI).