Infrared thermal mapping experiment: The Viking Mars orbiter

Abstract

The Mars infrared thermal mapper (IRTM) will be carried on the scan platform of the orbiter of the Viking 1975 mission. The IRTM is a multichannel radiometer with several detectors in each of six spectral regions. This instrument will measure the reflected solar radiation and surface thermal emission from the area viewed by the orbiter imaging system with nominal 5 km resolution. Extensive additional areas will be covered for which simultaneous imaging will not be available. The spectral channels are selected to be sensitive to surface emissivity variations and provide good temperature resolution over the entire range of Martian temperatures. These observations will allow determination of the surface kinetic temperature and thermal balance, and by coverage of the dark hemisphere, a search for regions with anomalous cooling can be made. Observations of ground frosts or clouds will help to determine their composition, and in the case of extensive H_2O frosts, will allow the local water vapor pressure to be estimated