Title: Progress in GeoSTAR technology development and risk reduction for PATH
Primary Author: Lambrigtsen, Bjorn
Organization: Jet Propulsion Laboratory
Co-Author(s): Bjorn Lambrigtsen, Todd Gaier, Alan Tanner, Pekka Kangaslahti, Shannon Brown, Boon Lim, Christopher Ruf

A synthetic-aperture microwave sounder was first proposed for the NASA New Millennium EO-3 mission in 1999, which resulted in a Phase A mission study. Between 2003 and 2006 a proof-of-concept ground based instrument was developed under IIP-03. That resulted in successful demonstration of the aperture synthesis concept as well as the development of key technology, such as 50-GHz miniature receivers and antenna feedhorns with low mutual coupling. In 2007 the National Research Council recommended in its ‘decadal survey’ of earth science missions that NASA undertake to develop the Precipitation and All-weather Temperature and Humidity (PATH) mission. A whitepaper had been submitted based on the GeoSTAR concept, and the NRC recommended that the PATH mission be implemented with an ‘array radiometer’. GeoSTAR is therefore viewed as the baseline payload for PATH. A second technology development effort has been under way since 2008 under IIP-07 with focus on risk reduction for the PATH mission. Key technology items not addressed under the first IIP effort, primarily related to the 183-GHz frequency band and high-speed chip-based correlators, are being developed under this effort. We report on significant progress in this development and its relevance to the PATH mission.