APL Colloquium

February 15, 2002

Colloquium Topic: From Geosat into the ABYSS: Ocean Radar Altimetry at APL

"To catch the moon from the bottom of the sea" is a very high scoring combination in the game of Mah-Jong. The Applied Physics Laboratory is planning to catch the bottom of the sea from the International Space Station (ISS), using an original instrument named ABYSS. It turns out that ABYSS and the ISS are a very high-scoring combination. Sea-bottom topography has been mapped by inverting sea surface slope data from height measurements provided by the Geosat radar altimeter, a 1980's mission designed, built, and operated by APL. ABYSS will measure sea-surface slopes down to one micro-radian, to spatial scales down to 6-km, and with balanced NS and EW slope measurement accuracy. These data will support an order-of-magnitude improvement in bathymetric maps, due primarily to the favorable inclination of the ISS orbit, and to the unique precision and attitude-tolerance of the altimeter. ABYSS relies on new concepts invented and flight-proven at APL. These same concepts also pave the way toward miniaturized dedicated radar altimeter satellites, radar altimeters that can measure the heights of sloping continental ice sheets, and improved ground-penetrating radar.

Colloquium Speaker: R. Keith Raney

R. Keith Raney received his B.S. degree in physics from Harvard University, his M.S. degree in electrical engineering from Purdue University, and a Ph.D. from the University of Michigan. Since 1994, he has been a member of the Ocean Remote Sensing Group in the Space Department of the Applied Physics Laboratory. Dr. Raney is the Project Scientist for the ABYSS altimeter now in Step Two selection competition for a NASA Earth Observing mission. He holds patents on the delay Doppler radar altimeter and an ice sounding radar, and he is the principal inventor for the U.S. patent on the chirp scaling SAR processing algorithm. He is on the Science Advisory Group for the European Space Agency's CryoSat radar altimeter, was Project Scientist for Canada's Radarsat system and was scientific authority for the Canadian Seasat processor, the world's first digital processor for satellite SAR data. Dr. Raney is a Fellow of the IEEE and the Electromagnetics Society, and a recipient of Group Achievement Awards for the Pioneer Venus and Magellan Radar Science Teams, the 1999 Gold Medal of the Canadian Remote Sensing Society, and the Millennium Medal 2000 from the IEEE, among other awards.