The primary payload on STS-54 was the fifth Tracking and Data Relay Satellite, deployed on day one of the mission. Also carried into orbit was an experiment called the Diffuse X-ray Spectrometer, which collected data on x-ray radiation from diffuse sources in deep space.
Multiple life sciences payloads were flown on STS-54, including the Physiological and Anatomical Rodent Experiment-02 (PARE.02), which also flew on STS-74, and the Chromosome and Plant Cell Division in Space Experiment (CHROMEX-03).
PARE.02 experiments continued the musculoskeletal studies that began during PARE.01, flown on STS-48. Together, these two payloads examined the extent to which short-term exposure to microgravity alters the size, strength and stamina of skeletal muscles normally used to help support the body against the force of gravity.
STS-54 was the third flight of the Chromosome and Plant Cell Division in Space Experiment (CHROMEX-3). CHROMEX payloads fly in the middeck of the Orbiter. The payload consisted of experiments that used the Plant Growth Unit (PGU), which allowed scientists to grow whole plants in orbit. The plants grew for the length of the mission and were analyzed after the mission to determine the effects of microgravity and space flight on their reproductive structures; there was little to no crew interaction with the payload.
Other life sciences experiments performed during the STS-54 mission were those classified as Detailed Supplementary Objectives (DSOs). A DSO is a NASA-sponsored investigation performed by Space Shuttle crewmembers, who serve as the test subjects. These studies are designed to require minimal crew time, power and stowage. Biomedical DSOs focus on operational concerns, including space motion sickness, cardiovascular deconditioning, muscle loss, changes in coordination and balance strategies, radiation exposure, pharmacokinetics and changes in the body's biochemistry.
Middeck payloads flown to test the effects of microgravity included the Commercial General Bioprocessing Apparatus for life sciences research, the Space Acceleration Measurement (SAMS) equipment to measure and record the microgravity acceleration environment of middeck experiments, and the Solid Surface Combustion Experiment to measure the rate of flame spread and temperature of burning filter paper.
On day five of the mission, Mission Specialists Mario Runco and Greg Harbaugh spent nearly five hours in the open cargo bay performing a series of space-walking tasks designed to increase NASA's knowledge of working in space. They tested their abilities to move about freely in the cargo bay, climb into foot restraints without using their hands and simulated carrying large objects in the microgravity environment.
The Space Shuttle Endeavour landed at Kennedy Space Center on January 19, 1993, after a one orbit delay due to ground fog.