Thursday 25 August 2005

G1

PTH0001
GRACE precision orbit determination using accelerometers
Bettadpur, Srinivas¹, Kang, Zhigui¹, Nagel, Peter¹, Pastor, Rick¹, Ries, John¹
1 Center For Space Research, The University Of Texas At Austin, USA
Author email: srinivas@csr.utexas.edu
The twin satellites of the NASA/DLR mission Gravity Recovery And Climate Experiment (GRACE) each carry a SuperSTAR accelerometer built by ONERA. The non-gravitational forces measured by this instrument are critical to the successful extraction of Earth gravity field information from the inter-satellite ranging measurement. In this paper, we assess the progress made towards 2-cm quality precision orbit determination (POD) of GRACE satellites, and the contribution of the accelerometers towards that goal. By comparing the GPS-tracking based dynamic POD with and without the accelerometers, we assess the relative contribution of mismodeling of the gravitational and non-gravitational forces towards POD. Such a comparison also is used to verify the calibration of the GRACE-derived mean Earth gravity field through its application to POD.

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