HR: 1340h
AN: G43A-0801    [Abstracts]
TI: Local Gravity Fields From Mars Express Residual Doppler Data
AU: * Beuthe, M
EM: mbeuthe@oma.be
AF: Royal Observatory of Belgium, Avenue Circulaire 3, Brussels, 1180 Belgium
AU: Barriot, J
EM: jean-pierre.barriot@cnes.fr
AF: Observatoire Midi-Pyr\'en\'ees, 14 Avenue Edouard Belin, Toulouse, 31401 France
AU: P\"atzold, M
EM: paetzold@geo.uni-koeln.de
AF: Institut f\"ur Geophysik und Meteorologie, Universit\"at zu K\"oln, Albertus-Magnus-Platz, K\"oln, 50923 Germany
AU: Rosenblatt, P
EM: pascal.rosenblatt@oma.be
AF: Royal Observatory of Belgium, Avenue Circulaire 3, Brussels, 1180 Belgium
AB: Planetary gravity fields can be studied in detail by measuring their effect on the velocity of an orbiting probe. Two main methods of analysis of the resulting Doppler data are available. Either a complete dynamical modeling of the probe orbit yields a global spherical harmonic gravity field, or a local analysis of the residual Doppler data leads to a model of the gravity field in a given area. The very elliptical orbit of Mars Express favors the second method, since only measurements near pericenter include a significant contribution from underlying gravity anomalies. The residual line-of-sight Doppler data provided by the MaRS experiment are inverted with a Tarantola-Valette stochastic procedure, with a priori knowledge of the solution given by a full correlation matrix constrained by the Kaula rule. As a result, the Doppler data are mapped as gravity disturbances on a sphere close to the planetary surface. Mars Express gravity data are expected to be especially useful for the study of polar caps, where the gravity field is not well known at the present.
DE: 5417 Gravitational fields (1227)
DE: 6225 Mars
DE: 1219 Local gravity anomalies and crustal structure
DE: 1227 Planetary geodesy and gravity (5420, 5714, 6019)
SC: Geodesy [G]
MN: 2004 AGU Fall Meeting