GeoSTAR: Developing a Microwave Sounder for Geostationary Weather Satellites

The Geostationary Synthetic Thinned Aperture Radiometer (GeoSTAR) is a new concept for a microwave sounder, intended to be deployed on NOAA's next generation of geostationary weather satellites, the GOES-R series. A ground based prototype has been developed at the Jet Propulsion Laboratory, under NASA Instrument Incubator Program (IIP) sponsorship, and is now undergoing tests and performance characterization. With the aperture synthesis approach used by GeoSTAR it is possible to achieve very high spatial resolutions even in the crucial 50-GHz temperature sounding band without having to deploy the impractically large parabolic reflector antenna that is required with the conventional approach. GeoSTAR will finally, after many years of searching for a solution, make it possible to add a microwave sounder to the GOES instrument suite - a capability that is crucial for monitoring cloudy regions and severe storms. The technology and system design required for GeoSTAR are rapidly maturing, and it is expected that a space demonstration mission can be developed before the first GOES-R launch. GeoSTAR will be ready for operational deployment 2-3 years after that. The prototype developed under IIP implements a small version of the temperature sounding component of GeoSTAR, is fully functional as a sounder and has all of the features and capabilities of an operational system with the exception of spatial resolution. It therefore represents a complete proof of concept as well as significant risk reduction for a space implementation. Further technology risk reduction, with particular focus on the 183-GHz water vapor sounding band, is also under way.