The Global Environmental Monitoring System (GEMS) CubeSat Microwave Radiometer Constellation for Weather and Climate Intelligence*

The need for persistent microwave imaging spectrometry of the Earth within 100-200 GHz and with sub-hourly temporal resolution for severe weather monitoring had been identified in 1978 by Staelin et al. in a NASA-sponsored study [1]. The clear need presented in this study has driven the laboratory-level development of large geostationary filled-and synthetic-aperture microwave sounders throughout the past period of more than four decades. However, the recent demonstration of small CubeSat-based imaging microwave spectrometers in this frequency range suggests a new pathway to achieving these goals. The successful launch in April 2019 and subsequent demonstration of the Global Earth Monitoring System (GEMS) GEMS-1 In-orbit Demonstration (IOD) mission using a 118-GHz imaging microwave spectrometer supports this goal. Importantly, however, it enables a scalable constellation framework with the capability to provide temporal Nyquist-sampled microwave imagery of the Earth’s troposphere and lower stratosphere.

GEMS-1 IOD was developed by Orbital Micro Systems in partnership with the University of Colorado’s Center for Environmental Technology and the UK Space Applications Catapult. The GEMS-1 IOD sensor is currently the highest spatial resolution microwave temperature sounding sensor on orbit. The GEMS-1 sensor design, its on-orbit performance, and the pathway to an evolved GEMS constellation capable of meeting and exceeding the severe weather observation requirements set forth over 40 years ago will be discussed.

[1] “High Resolution Passive Microwave Satellites”, D.H. Staelin and P.W. Rosenkranz (eds.), Applications Review Panel Final Report for NASA, MIT Research Laboratory for Electronics, 14 April 1978.