Overview of the TROPICS Flight Segment

The Time-Resolved Observations of Precipitation structure and storm Intensity with a Constellation of Smallsats (TROPICS) mission was selected by NASA in 2016 as part of the Earth Venture Instrument (EVI-3) program and is now in development with planned launch readiness in late 2019. The TROPICS constellation consists of six CubeSats, two in each of three low-Earth orbital planes with a nominal circular orbit of 550 km and inclination of 30°. Each CubeSat hosts a highperformance radiometer payload with twelve microwave channels, providing atmospheric temperature profiles, water vapor profiles, and rain rate. The TROPICS mission will produce rapid-refresh microwave measurements (median refresh rate of approximately 40 minutes for the baseline mission) over the Tropics that will enable observations of the entire tropical storm lifecycle. The radiometer design is similar to two other MIT Lincoln Laboratory (MIT LL) CubeSat programs, MicroMAS and MiRaTA, with improvements to meet enhanced performance requirements and longer mission life. The CubeSat bus is under contract with a commercial vendor who will integrate the MIT LL payload and their bus, and test the complete space vehicle. This paper will describe the mission, present various aspects of the payload and bus design, and describe the assembly, integration and test flow.