The Thermal Emission Imaging System (THEMIS) on NASA’s Mars Odyssey orbiter (launched in 2001) is a multi-spectral thermal infrared imager designed to map surface mineralogy and temperature. In the context of atmospheric studies, THEMIS nadir radiances enable retrievals of column dust optical depth, extending dust-monitoring capabilities beyond those from the Mars Global Surveyor/Thermal Emission Spectrometer (MGS/TES) mission into later Martian years.