The Atmospheric X-ray Emission Telescope (AXET) is designed to image and measure the spatial, temporal, and spectral distributions of x-ray aurorae produced in the upper atmosphere by precipitating energetic electrons. The bremsstrahlung produced x-ray radiation penetrates to stratospheric depths where it can modify ozone, conductivity, and other critical atmospheric parameters. Remote sensing of this radiation from topside will provide vital data on solar-terrestrial relationships and mechanisms that could help trigger tropospheric response to solar activity. The X rays also provide direct information concerning the dynamics of radiation belt processes within the magneto-sphere. AXET is designed to detect sources up to 50 keV and to image them below 25 keV by means of directionally sensitive proportional counters with passive collimators. It will be mount-ed in the space shuttle on a single, fixed platform designed to optimize viewing conditions for the anticipated orbits and as-pects of early Spacelab missions. A more sophisticated instru-ment is proposed for later missions when instrument pointing systems are available. This instrument concept is based on a two-dimensional spatially sensitive multiwire proportional counter with appropriate collimators, and will provide improved sensitivity and resolution.