Development and Flight Qualification of the Millimeterwave Receivers for the NASA TROPICS CubeSat Constellation Mission

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 and is now in development with planned launch readiness in late 2019. 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. Thermal vacuum test results on the qualification unit and first set of flight unites indicate that all technical requirements have been met. NEDTs range from approximately 0.5 to 1.0 K for an 8.333 msec integration time. Spatial resolution at nadir ranges from approximately 15 km for the G-band channels to 30 km for the W-band channels.