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Precision GPS ephemerides and baselinesThe required knowledge of the Global Positioning System (GPS) satellite position accuracy can vary depending on a particular application. Application to relative positioning of receiver locations on the ground to infer Earth's tectonic plate motion requires the most accurate knowledge of the GPS satellite orbits. Research directed towards improving and evaluating the accuracy of GPS satellite orbits was conducted at the University of Texas Center for Space Research (CSR). Understanding and modeling the forces acting on the satellites was a major focus of the research. Other aspects of orbit determination, such as the reference frame, time system, measurement modeling, and parameterization, were also investigated. Gravitational forces were modeled by truncated versions of extant gravity fields such as, Goddard Earth Model (GEM-L2), GEM-T1, TEG-2, and third body perturbations due to the Sun and Moon. Nongravitational forces considered were the solar radiation pressure, and perturbations due to thermal venting and thermal imbalance. At the GPS satellite orbit accuracy level required for crustal dynamic applications, models for the nongravitational perturbation play a critical role, since the gravitational forces are well understood and are modeled adequately for GPS satellite orbits.
Document ID
19920010486
Acquisition Source
Legacy CDMS
Document Type
Contractor Report (CR)
Date Acquired
September 6, 2013
Publication Date
February 25, 1992
Subject Category
Astronomy
Report/Patent Number
NASA-CR-189924
NAS 1.26:189924
Accession Number
92N19728
Funding Number(s)
CONTRACT_GRANT: NAG5-940
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.

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