The Upper Atmospheric Research Satellite was designed to study the physical and chemical processes occurring in the Earth's upper atmosphere (between 15 and 100 km).

The vehicle provided measurements of atmospheric internal structure (trace constituents, physical dynamics, radiative emission, thermal structure, density) and measurements of the external influences acting upon the upper atmosphere (solar radiation, tropospheric conditions, electric fields). The specific UARS mission objectives were to study energy input and loss in the upper atmosphere, global photochemistry of the upper atmosphere, dynamics of the upper atmosphere, coupling among these processes, and coupling between the upper and lower atmosphere. The spacecraft was 3-axis stabilized via reaction wheels, torque rods to 36 arc seconds. Attitude knowledge to 20 arc seconds used star trackers, Earth sensors, an inertial reference unit, and Sun sensors. The single solar array was 1.5 x 3.3 meters and generated 1.6 kW, recharging 3 x 50 A-hr batteries. The hydrazine propulsion system provided for orbit insertion and maintenance. S-band communications was via low gain antennas and a gimbaled high gain antenna through TDRSS. The payload included:

• Cryogenic Limb Array Etalon Spectrometer (CLEAS).
• Improved Stratospheric and Mesospheric Sounder (ISAMS).
• Microwave Limb Sounder (MLS).
• Halogen Occultation Experiment (HALOE).
• High Resolution Doppler Imager (HRDI).
• Wind Imaging Interferometer (WINDII).
• Solar-Stellar Irradiance Comparison Experiment (SOLSTICE).
• Solar Ultraviolet Spectral Irradiance Monitor (SUSIM).
• Particle Environment Monitor (PEM).
• Active Cavity Radiometer Irradiance Monitor (ACRIM II).

Design Life: 3 years. Typical orbit: 585 km circular, 57 deg inclination. Length: 9.80 m (32.10 ft). Maximum Diameter: 4.60 m (15.00 ft). Mass: 6,795 kg (14,980 lb).

• 1991 September 12 - UARS - Launch Site: Cape Canaveral. Launch Complex: LC39A. Launch Vehicle: Shuttle. Mass: 6,795 kg (14,980 lb). Perigee: 574 km (356 mi). Apogee: 582 km (361 mi). Inclination: 57.00 deg. Period: 96.20 min.
  Upper Atmospheric Research Satellite; deployed from STS 48 9/15/91. Spacecraft engaged in research and exploration of the upper atmosphere or outer space (US Cat B).