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| Titel |
Improvement of ERS-1 orbits using along-track accelerations from DORIS data on SPOT2 |
| VerfasserIn |
S. Ehlers, P. Moore |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
0992-7689
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| Digitales Dokument |
URL |
| Erschienen |
In: Annales Geophysicae ; 12, no. 8 ; Nr. 12, no. 8, S.775-784 |
| Datensatznummer |
250011035
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| Publikation (Nr.) |
 copernicus.org/angeo-12-775-1994.pdf |
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| Zusammenfassung |
| In long-arc precise orbit determinations of
altimetric satellites such as ERS-1, large errors may occur from mismodelling of
aerodynamic drag and solar radiation pressure. Such surface forces for
non-spherical satellites require accurate modelling of the effective area and
particle-surface interactions, but the dominant source of error is neutral air
density as derived from thermospheric models for aerodynamic drag. Several
techniques can be employed to alleviate air-drag mismodelling but all require
the solution of additional parameters from the tracking data. However, for ERS-1
the sparsity of laser range data limits the application of such empirical
techniques. To overcome this, use can be made of the dense DORIS Doppler
tracking for SPOT2 which is in a similar orbit to ERS-1. A recent investigation
by CNES examined the use of drag scale factors from SPOT2 to constrain the ERS-1
orbit. An improvement to that methodology is to consider along-track
mismodelling as observed by timing errors in the Doppler data for each pass of
SPOT2. The along-track correction to the acceleration as derived from SPOT2 can
then be applied to ERS-1 orbits, solving for a scale factor to absorb systematic
errors - particularly that arising from the 50 km altitude difference. Results
are presented of the associated improvement in ERS-1 orbits as derived from
concurrent SPOT2 arcs. It will be seen that the procedure not only improves the
laser range fit, but more importantly, leads to more precise radial positioning
as evident in the altimeter and crossover residuals. |
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