Development of wind measurement systems for future space missions

Abstract

An essential physical quantity for the understanding of planetary systems is dynamics; that is, atmospheric winds. Relatively few wind measurement missions have been conducted in past decades, but there is a current renewed interest. This manuscript is concerned with optical remote sensing methods, but in-situ approaches, such as mass spectrometers on satellites are also briefly included. The optical methods are based on Doppler shifts of atmospheric emission or absorption features. This survey considers three classes of optical spectroscopic systems, the Fabry–Perot Spectrometer (FPS), the Doppler Michelson Interferometer (DMI) and the Spatial Heterodyne Spectrometer (SHS). The FPS is a quadratic system, in which the change of wavelength corresponding to a change of off-axis angle inside the instrument goes as the square of the angle. The DMI is a fourth-order system, allowing higher values of solid angle of acceptance and the same is true for the SHS. Approaches additional to the optical methods, mass spectrometers, sub-millimetre wave radiometry, gas cell absorption technology and lidar are briefly described. Examples of results from past missions are presented and possible directions for future missions described.