Monitoring the Ocean with Navy Radar Altimeter Lightsats

A system of three radar altimeter LightSats would provide optimum temporal and spatial sampling of the sea surface height signatures of ocean features at mid latitudes and above. Merging this data with satellite infrared images would provide a robust, affordable, all-weather, global ocean monitoring system in support of the Navy Tactical Oceanography mission. The present Navy system for mapping ocean features uses sea surface temperature maps from NOAA satellite radiometers and sea surface height profiles from the Navy GEOSA T radar altimeter satellite. GEOSAT is a 1450-pound, completely redundant satellite with a 207-pound, 165-watt radar altimeter. GEOSAT was developed by JHU/APL and launched in March 1985 on an Atlas-E. A lightsat-compatible radar altimeter instrument has now been developed at APL that achieves full GEOSAT measurement capability In one-half the weight and power (95 pounds and 69 watts), primarily by applying the latest advances in RF and digital components. A form, fit, and function engineering model of the altimeter is being fabricated for performance validation. The conceptual design of GEOSCOUT, a Scout launched version of the GEOSAT satellite, was completed to establish the technical feasibility of the radar altimeter lightsat concept. The spacecraft weight was reduced to 395 pounds and the configuration made Scout-compatible. These weight and volume reductions were made possible by downsizing the instrument, eliminating subsystem redundancy, and by updating subsystem designs. The success of the GEOSCOUT conceptual design has encouraged APL to pursue the next logical step: a combined altimeter/radiometer lightsat. Work on that concept has now begun.