Microwave Observatory of Subcanopy and Subsurface (MOSS) IIP: Final Results and Next Steps

The microwave observatory of subcanopy and subsurface (MOSS) project has been supported under the ESTO IIP to develop technologies for a SAR mission that provides global observations of soil moisture under substantial vegetation canopies and at useful depths. This VHF/UHF polarimetric SAR is designed to provide 7-10 day repeat observations of soil moisture under substantial vegetation canopies and at depths reaching 1-5 meters, at 1 Km resolution. Due to the rapid repeat cycle, the required swath width is 300-400 Km, which must be realized by a 30m long antenna. Conventional array implementations would result in a mass of over 4000 Kg, whereas with the technology proposed and demonstrated in this project, the total antenna mass becomes about 400 kg. This antenna concept is implemented by a dual-stack patch array feed illuminating a 30m mesh reflector to synthesize the required long rectangular apertures and achieve the wide swath. This feed system was designed, and a prototype built and demonstrated. Initially, a scaled version was built and tested, which was also integrated with a scaled reflector antenna for demonstration of the overall antenna system. The full-size low frequency feed was also built and its performance successfully demonstrated. The technology was therefore taken to TRL 5-6 from 3. Other components of this project were the demonstration of the science data and products, which was achieved through a tower-based VHF/UHF radar. Experimental data were generated for deep penetration in the Arizona desert, as well as for forest penetration in a dense forest in Oregon. The soil moisture products were demonstrated and in so doing, a novel integrated inversion-processing algorithm was developed. This presentation will cover the projects accomplishment and suggest some possible next steps to realize this concept as an Earth orbiting mission.