UARS (Upper Atmosphere Research Satellite) is a NASA satellite designed to study the physical and chemical processes taking place in Earth's upper atmosphere, between 15 and 100 kilometers. UARS 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 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.