HR: 1340h
AN: SF43A-0787    [Abstracts]
TI: Development of an Interferometric Laser Ranging System for a Follow-On Gravity Mission to GRACE
AU: * Nerem, R S
EM: nerem@colorado.edu
AF: University of Colorado, UCB431, Boulder, CO 80309-0431 United States
AU: Bender, P
EM: pbender@jila.colorado.edu
AF: University of Colorado, UCB431, Boulder, CO 80309-0431 United States
AU: Loomis, B
EM: bryant.loomis@colorado.edu
AF: University of Colorado, UCB431, Boulder, CO 80309-0431 United States
AU: Geiple, J
EM: joshua.geiple@colorado.edu
AF: University of Colorado, UCB431, Boulder, CO 80309-0431 United States
AU: Watkins, M
EM: michael.m.watkins@jpl.nasa.gov
AF: Jet Propulsion Laboratory, 4800 Oak Grove Dr., Pasadena, CA 91109 United States
AU: Folkner, W
EM: william.m.folkner@jpl.nasa.gov
AF: Jet Propulsion Laboratory, 4800 Oak Grove Dr., Pasadena, CA 91109 United States
AU: Stephens, M
EM: mstephens@ball.com
AF: Ball Aerospac Technologies Corp., P.O. Box 1062, Boulder, CO 80301 United States
AU: Delker, T
EM: tdelker@ball.com
AF: Ball Aerospac Technologies Corp., P.O. Box 1062, Boulder, CO 80301 United States
AU: Leitch, J
EM: jleitch@ball.com
AF: Ball Aerospac Technologies Corp., P.O. Box 1062, Boulder, CO 80301 United States
AU: Pierce, R
EM: rpierce@ball.com
AF: Ball Aerospac Technologies Corp., P.O. Box 1062, Boulder, CO 80301 United States
AB: The Gravity Recovery and Climate Experiment (GRACE) has ushered in a new era for satellite measurements of the Earth system. GRACE provides monthly estimates of the time-varying gravity field, which are largely due to the redistribution of water mass in the Earth system, with a spatial resolution of ~500 km and an accuracy of 1 cm equivalent water. This is accomplished via a suite of instruments including a microwave ranging system, precision accelerometers for measuring non-gravitational forces, and a GPS navigation system. These tremendous advances made by GRACE have led to an interest in launching a follow-on mission with even better performance. The spatial resolution can be improved by improving the ranging performance, implementing a drag-free control system, and flying at a lower altitude. This presentation will focus on our effort to develop an interferometric laser ranging system that we expect to perform near the 1 nm/sec level or better over 5 second intervals, which when coupled with other mission improvements, would improve the spatial resolution to ~100 km for 1 cm water equivalent accuracy. We have designed a laser ranging system and are building an engineering model of the instrument, with which we will demonstrate its accuracy in the laboratory over the next few years. The laser system will range directly to the proof masses of the drag-free system, eliminating many of the difficulties associated with post-processing the accelerometer data on GRACE. We will also present the results of an error analysis for the ranging system, how these errors are expected to propagate into the gravity field estimates, and discuss the potential science benefits. In addition, we will show preliminary results from our laboratory tests of the breadboard design.
DE: 1214 Geopotential theory and determination
DE: 1294 Instruments and techniques
SC: Special Focus: Advances in Data Acquisition, Management, Analysis and Display [SF]
MN: 2004 AGU Fall Meeting