In-Flight Calibration of the Wind Imaging Interferometer (WINDII) on Board the Upper Atmosphere Research Satellite

The Wind Imaging Interferometer (WINDII) was launched on the Upper Atmosphere Research Satellite to measure the Earth's upper-atmospheric wind and temperature. It is a remote-sensing instrument that employs a field-compensated Michelson interferometer to measure the Doppler shift, line width, and emission rate of naturally occurring airglow emission lines. The data analysis uses calibration data that were obtained in the laboratory prior to launch. A calibration package to monitor instrument parameters was built and placed in the instrument. This package consists of a He-Ne laser, spectral lamps, and a tungsten lamp. These sources and their performance during six years of operation in orbit are described. It is shown that the WINDII principle of wind measurement can be assessed fully by the use of in-flight calibration data and that the preflight and in-flight phase calibrations can be related to each other with a precision of the order of 1 ms(-1).