An innovative approach to satellite ocean altimetry is proposed that combines modern advances in navigation and communications. By combining the Global Positioning System (GPS), for real time orbit determination, spread spectrum precision ranging and solid state microwave phased array antenna methods. a system is formed called the GPS Enabled Spread Spectrum Altimeter (GESSA). Using the precision orbit information on-board the satellite, the spread spectrum ranging system can be optimally controlled. The electronically steered phased array antenna allows for variable altimeter swath widths. In addition to providing 2 cm accuracy altimetry. the spread spectrum ranging enables a single frequency approach to ionospheric calibration that eliminates the need for a second frequency radar on board the satellite which traditional incurred significant cost penalties. The GESSA approach is well suited to small spacecraft missions while matching or exceeding the state-of-the-art in spaceborne ocean altimetry and at a considerable savings.On a world-wide basis, there are now many maturing satellite companies that are specializing in very small satellite missions which will be customized to specific client needs. GESSA will have application for the maritime industry. by exploiting ocean altimetry capability in open ocean topographic measurement from which circulation anomalies of fronts and eddies can be located. Such oceanic topographic information is very useful in the fishing industry and to offshore platform operations. In addition, the altimetry sensitivity to sea state and sea ice offers an important space business opportunity for the real time measurement of sea roughness and navigation hazards information development with a fee based dissemination service to maritime users. The attractiveness of such space business opportunities depends critically upon demonstrated GESSA accuracy and affordability of the relevant space instrument system. Once the GESSA system is actually demonstrated, there will be a great demand for such instruments, and their oceanographic data products will enjoy a global market demand.
Keywords: Phase_I, NASA, Abstract, FY94
