《ANALYSIS OF SATELLITE LASER ALTIMETRY RANGE MEASUREMENTS OVER LAND》.pdfVIP

ANALYSIS OF SATELLITE LASER ALTIMETRY RANGE MEASUREMENTS OVER LAND TOPOGRAPHY USING GENERALIZED ATTITUDE PARAMETER EXTRACTION J. R. Ridgway, J.B. Minster Institute of Geophysics and Planetary Physics University of California, San Diego U.S.A. ridgway@spot.ucsd.edu, jbminster@ucsd.edu KEY WORDS: Laser Altimetry, Satellite, Topography, Attitude, Pointing ABSTRACT Two new laser altimeter satellites are being launched by NASA in the near future: the ICESat (Ice, Clouds, Elevation) satellite and the VCL (Vegetation Canopy Lidar) satellite. Although each satellite has a different emphasis (ICESat concentrating on ice sheets and VCL on vegetation), both will fly over land for a large portion of their orbit. The alignment of the laser is set prior to launch; however, forces on lift-off may cause a mis-alignment. Traditionally these “attitude biases” in aircraft are calculated using dedicated roll/pitch maneuvers over a flat surface such as a lake or the ocean. An alternative method to this procedure is the measurement of topography along the satellite ground-track and comparison of the measured profile to a well-known “truth grid”. The residual topographic signal would then be analyzed and related to spacecraft attitude, range and other mis-alignment sources. We propose an attitude extraction approach whereby any given measured profile is related to the truth grid by a laser pointing vector. In addition, there may exist orbit and timing errors. The determination of these parameters involves a search for a minimum in a m