TECHNOLOGY MATURATION ACHIEVED THROUGH THE NASA TROPICS MISSION

Abstract

The Time-Resolved Observations of Precipitation structure and storm Intensity with a Constellation of Smallsats (TROPICS) mission was selected by NASA as part of the Earth Venture--Instrument (EVI-3) program. TROPICS comprises a constellation of six CubeSats in three low-Earth low-inclination orbital planes. Each CubeSat will host a high performance millimeterwave radiometer to provide temperature profiles using seven channels near the 118.75 GHz oxygen absorption line, water vapor profiles using three channels near the 183 GHz water vapor absorption line, imagery in a single channel near 90 GHz for precipitation measurements (when combined with higher resolution water vapor channels), and a single channel at 205 GHz that is more sensitive to precipitation-sized ice particles. Spatial resolution at nadir ranges from approximately 15 km for the G-band channels to 30 km for the W-band channels. The Pathfinder (Qualification Unit) was launched on June 30, 2021, and the six constellation flight units are scheduled to launch in the first half of 2022. The TROPICS program has matured several key technologies for small satellite remote sensing using microwave radiometers, including self-calibrating millimeterwave receivers, low-power radiometer systems, low-loss antenna assembly, and compact mechanical scanner. This paper summarizes the key receiver and antenna technologies, proven by the successful Pathfinder mission and slated for further use in the constellation mission [4].