Upper Atmospheric Research Satellite. UARS was designed to study the physical and chemical processes occurring in the Earth's upper atmosphere (between 15 and 100 km). The vehicle provides 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 are to study 1) energy input and loss in the upper atmosphere, 2) global photochemistry of the upper atmosphere, 3) dynamics of the upper atmosphere, 4) coupling among these processes, 5) coupling between the upper and lower atmosphere. Spacecraft: 3-axis stabilised via reaction wheels, torque rods to 36 arc seconds. Attitude knowledge to 20 arc seconds using star trackers, Earth sensors, IRU, Sun sensors. Single solar array is 1.5 x 3.3 meters and generates 1.6 kW.3 50 A-hr batteries. Hydrazine propulsion system for orbit insertion and maintenance. S-band communications via low gain antennas and gimballed high gain antenna through TDRSS. Payload: 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. Total Length: 9.8 m. Maximum Diameter: 4.6 m. Total Mass: 6,795 kg.
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).