GeoSTAR - A New Approach for a Geostationary Microwave Sounder

The Geostationary Synthetic Thinned Aperture Radiometer (GeoSTAR) is a microwave atmospheric sounder, with capabilities similar to those of the AMSU-A/B system, and is intended for deployment in geostationary orbit – where it will complement future infrared sounders t o enable all-weather temperature and humidity soundings. It also has the capability of mapping rain rates, and it can be deployed in medium earth orbits as well. GeoSTAR is based on spatialinterferometric principles and uses a stationary array of a large number of individual receivers t o synthesize a large aperture and achieve the required spatial resolution, an approach that has significant advantages over conventional real-aperture systems – such as full-disk scanning with no moving parts. GeoSTAR will implement the same tropospheric sounding channels as AMSU-A (temperature) and AMSU-B (humidity) and will achieve an initial spatial resolution of 25-50 km. Future versions will have significantly higher spatial resolution. The required technology is currently being developed at the Jet Propulsion Laboratory and other collaborating organizations, under NASA’s Instrument Incubator Program, and a ground based demo system will be ready in 2005.