This photograph depicts the Solar X-Ray Imager (SXI) being installed in the X-Ray Calibration Facility (XRCF) vacuum chamber for testing at the Marshall Space Flight Center (MSFC). The XRCF vacuum chamber simulates a space environment with low temperature and pressure. The x-ray images from SXI on the Geostationary Operational Environmental Satellite-12 (GOES-12) will be used by the National Oceanic and Atmospheric Administration (NOAA) and U.S. Air Force to forecast the intensity and speed of solar disturbances that could destroy satellite electronics or disrupt long-distance radio communications. The SXI will observe solar flares, coronal mass ejections, coronal holes, and active regions in the x-ray region of the electromagnetic spectrum. These features are the dominant sources of disturbances in space weather. The imager instrument consists of a telescope assembly with a 6.3-inch (16-centimeter) diameter grazing incidence mirror and a detector system. The imager was developed, tested, and calibrated by MSFC, in conjunction with the NASA Goddard Space Flight Center and U.S. Air Force.