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| Titel |
Space Gravity Spectroscopy - determination of the Earth’s gravitational field by means of Newton interpolated LEO ephemeris Case studies on dynamic (CHAMP Rapid Science Orbit) and kinematic orbits |
| VerfasserIn |
T. Reubelt, G. Austen, E. W. Grafarend |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1680-7340
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| Digitales Dokument |
URL |
| Erschienen |
In: G1. The new gravity field mission (CHAMP, GRACE, GOCE): from measurements to geophysical interpretation ; Nr. 1 (2003-07-11), S.127-135 |
| Datensatznummer |
250000047
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| Publikation (Nr.) |
 copernicus.org/adgeo-1-127-2003.pdf |
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| Zusammenfassung |
An algorithm for the (kinematic) orbit analysis
of a Low Earth Orbiting (LEO) GPS tracked satellite to determine
the spherical harmonic coefficients of the terrestrial
gravitational field is presented. A contribution to existing
long wavelength gravity field models is expected since the
kinematic orbit of a LEO satellite can nowadays be determined
with very high accuracy in the range of a few centimeters.
To demonstrate the applicability of the proposed
method, first results from the analysis of real CHAMP Rapid
Science (dynamic) Orbits (RSO) and kinematic orbits are
illustrated. In particular, we take advantage of Newton’s
Law of Motion which balances the acceleration vector and
the gradient of the gravitational potential with respect to an
Inertial Frame of Reference (IRF). The satellite’s acceleration
vector is determined by means of the second order functional
of Newton’s Interpolation Formula from relative satellite
ephemeris (baselines) with respect to the IRF. Therefore
the satellite ephemeris, which are normally given in
a Body fixed Frame of Reference (BRF) have to be transformed
into the IRF. Subsequently the Newton interpolated
accelerations have to be reduced for disturbing gravitational
and non-gravitational accelerations in order to obtain the accelerations
caused by the Earth’s gravitational field. For a
first insight in real data processing these reductions have
been neglected. The gradient of the gravitational potential,
conventionally expressed in vector-valued spherical harmonics
and given in a Body Fixed Frame of Reference, must be
transformed from BRF to IRF by means of the polar motion
matrix, the precession-nutation matrices and the Greenwich
Siderial Time Angle (GAST). The resulting linear system of
equations is solved by means of a least squares adjustment
in terms of a Gauss-Markov model in order to estimate the
spherical harmonics coefficients of the Earth’s gravitational
field.
Key words. space gravity spectroscopy, spherical harmonics
series expansion, GPS tracked LEO satellites, kinematic |
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