On-orbit performance of the WINDII instrument on the Upper Atmosphere Research Satellite (UARS)

The wind imaging interferometer (WINDII) on the Upper Atmosphere Research Satellite (UARS) is a CCD imager which views a selection of airglow emissions at the limb through a field-widened Michelson interferometer. Winds are calculated from the Doppler shifts of the spectral lines, detected as changes in the phase of the fringes. WINDII has been operating in space for almost three years and its performance has been monitored over that time. It continues to function well, though subtle changes have been seen. This paper is a discussion of the endurance of the instrument and of the changes that have occurred during the mission.