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An improved model of the Earth's gravitational field: GEM-T1Goddard Earth Model T1 (GEM-T1), which was developed from an analysis of direct satellite tracking observations, is the first in a new series of such models. GEM-T1 is complete to degree and order 36. It was developed using consistent reference parameters and extensive earth and ocean tidal models. It was simultaneously solved for gravitational and tidal terms, earth orientation parameters, and the orbital parameters of 580 individual satellite arcs. The solution used only satellite tracking data acquired on 17 different satellites and is predominantly based upon the precise laser data taken by third generation systems. In all, 800,000 observations were used. A major improvement in field accuracy was obtained. For marine geodetic applications, long wavelength geoidal modeling is twice as good as in earlier satellite-only GEM models. Orbit determination accuracy has also been substantially advanced over a wide range of satellites that have been tested.
Document ID
19870020534
Acquisition Source
Legacy CDMS
Document Type
Technical Memorandum (TM)
Authors
Marsh, J. G. (NASA Goddard Space Flight Center Greenbelt, MD, United States)
Lerch, F. J. (NASA Goddard Space Flight Center Greenbelt, MD, United States)
Christodoulidis, D. C. (NASA Goddard Space Flight Center Greenbelt, MD, United States)
Putney, B. H. (NASA Goddard Space Flight Center Greenbelt, MD, United States)
Felsentreger, T. L. (NASA Goddard Space Flight Center Greenbelt, MD, United States)
Sanchez, B. V. (NASA Goddard Space Flight Center Greenbelt, MD, United States)
Smith, D. E. (NASA Goddard Space Flight Center Greenbelt, MD, United States)
Klosko, S. M. (NASA Goddard Space Flight Center Greenbelt, MD, United States)
Martin, T. V. (NASA Goddard Space Flight Center Greenbelt, MD, United States)
Pavlis, E. C. (NASA Goddard Space Flight Center Greenbelt, MD, United States)
Date Acquired
September 5, 2013
Publication Date
July 1, 1987
Subject Category
Geophysics
Report/Patent Number
NAS 1.15:4019
REPT-87B0451
NASA-TM-4019
Accession Number
87N29967
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.

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