Global Environmental Monitoring System (GEMS)

Global Environmental Monitoring System (GEMS) is Weather Stream's constellation of CubeSats carrying passive microwave radiometers that observe atmospheric temperature, humidity and precipitation. Optical sensors are limited by cloud and darkness and infrared sensors cannot see through cloud, while regions such as South and Central Asia, Africa and the poles are under-observed. GEMS radiometers work through cloud cover and at night, producing three-dimensional temperature and moisture profiles of the atmosphere that are used to improve numerical weather prediction.

The first satellite, IOD-1 GEMS, a 3U CubeSat with an 8-channel 118 GHz radiometer, was deployed from the International Space Station in July 2019; the company describes it as the first commercial microwave radiometer in orbit. In October 2019 it observed Super Typhoon Hagibis during a gap between government satellites, and its data was used in datasets purchased by the U.S. Air Force and other public agencies. The second-generation GEMS2 radiometer is designed for 24 sounding and imaging channels in the 118 GHz and 183 GHz bands across a swath of about 2,000 km. The first GEMS2 satellite, GEMS2-Amethyst, launched on 30 March 2026 and was listed by the WMO as commissioning in April 2026. Weather Stream plans to expand the constellation towards sub-hourly global revisits. In 2020 Frost & Sullivan selected the company, then named Orbital Micro Systems, for its Global Enabling Technology Leadership Award in Environmental Monitoring Systems for the GEMS constellation.

In September 2024 NOAA awarded Weather Stream a Commercial Weather Data Pilot contract to supply GEMS passive microwave sounder observations for evaluation in numerical weather prediction, climate modelling and disaster preparedness. GEMS data is available in formats including NetCDF, and Weather Stream targets insurance, transportation, energy, mining, agriculture, finance and government users.