The primary payload of the flight was the Atmospheric Laboratory for Applications and Science-2 (ATLAS-2), designed to collect data on the relationship between the sun's energy output and Earth's middle atmosphere and how these factors affect the ozone layer. It included six instruments mounted on a Spacelab pallet in the cargo bay, with the seventh mounted on the wall of the bay in two Get Away Special canisters. Atmospheric instruments included the Atmospheric Trace Molecule Spectroscopy (ATMOS) experiment, the Millimeter Wave Atmospheric Sounder (MAS), and the Shuttle Solar Backscatter Ultraviolet/A (SSBUV/A) spectrometer (on the cargo bay wall). Solar science instruments were the Solar Spectrum Measurement (SOLSPEC) instrument, the Solar Ultraviolet Irradiance Monitor (SUSIM), and the Active Cavity Radiometer (ACR) and Solar Constant (SOLCON) experiments.