Stable and rugged etalon for the Dynamics Explorer Fabry-Perot interferometer. 2: Performance

This is the second of two papers which describe the development and performance of the Fabry-Perot etalon flown on the Dynamics Explorer spacecraft. The Dynamics Explorer instrument is designed to measure winds in the upper atmosphere by observing the Doppler shift of various emission features. The etalon remains stable to <5-m/sec equivalent wind over one orbit and <100 m/sec over several months in orbit. This paper discusses the thermal stability considerations for the highly stable etalon including the passive thermal control used in flight and presents a new kinematic etalon mount design which eliminates undesirable thermomechanical coupling between the etalon and its mount. A series of thermal vacuum tests has identified the major causes of thermally induced drift in the etalon transmission. The performance of the flight etalon is discussed.