The TROPICS Millimeter-wave Sounder (TMS) is the payload aboard each of a constellation of small satellites (SmallSats) comprising the Time-Resolved Observations of Precipitation structure and storm Intensity with a Constellation of SmallSats (TROPICS) mission. The instrument is a 12-channel passive microwave spectrometer providing imagery near 90 and 205 gigahertz (GHz), temperature sounding near 118 GHz, and moisture sounding near 183 GHz. 

TMS facilitates the study of water droplets (W-band; 92 GHz), brightness temperatures (i.e., radiance, F-band; 114 to 119 GHz), and moisture (G-band; 183 and 204 GHz), and provides frequent temperature and humidity profiles in all weather conditions.