HR: 14:40h
AN: P33C-05    [Abstracts]
TI: Improvement Of The Ephemeris And Mass Of The Martian Moons From MEX Precise Orbit Determination
AU: * Rosenblatt, P
EM: rosenb@oma.be
AF: Royal Observatory of Belgium, Av. Circulaire 3, Brussels, B-1180, Belgium
AU: Lainey, V
EM: Valery.Lainey@imcce.fr
AF: Institut de Mécanique Céleste et de Calcul des Ephémérides, 77 Av. Denfert-Rochereau, Paris, F-75014, France
AU: Le Maistre, S
EM: smaistre@oma.be
AF: Royal Observatory of Belgium, Av. Circulaire 3, Brussels, B-1180, Belgium
AU: Marty, J
EM: jean-charles.marty@cnes.fr
AF: GRGS/CNES, 14 Av. Edouard Belin, Toulouse, F-31401, France
AU: Dehant, V
EM: v.dehant@oma.be
AF: Royal Observatory of Belgium, Av. Circulaire 3, Brussels, B-1180, Belgium
AU: Paetzold, M
EM: paetzold@geo.uni-koeln.de
AF: Institut fur Geophysik und Meteorologie, Cologne University, Albertus-Magnus-Platz, Cologne, D-50923, Germany
AU: van Hoolst, T
EM: timvh@oma.be
AF: Royal Observatory of Belgium, Av. Circulaire 3, Brussels, B-1180, Belgium
AU: Hauesler, B
EM: bernd.haeusler@unibw-muenchen.de
AF: Institut für Raumfahrttechnik, Werner-Heisenberg-Weg 39, Universitat Bundeswehr Muenchen, Neubiberg, D-85577, Germany
AB: Because of the much larger eccentricity of the MEX orbit than that of the MGS orbit (eccentricity of 0.6 versus 0.01), MEX is more sensitive to the gravitational attraction of the Martian moons Phobos and Deimos. From the 2-way Doppler and range data provided by the MEX Radio Science (MaRS) experiment over the last three years, we perform MEX Precise Orbit Determination (POD) in order to improve both moons' ephemeris and mass. We use the GINS software developed by CNES and further adapted at ROB for planetary geodesy applications. We obtain an average precision of 20 meters or less on the MEX positioning around Mars. This represents an improvement by more than a factor 2 with respect to the MEX navigation orbit provided by the flight dynamics team of ESOC. Here, we show the impact of the improved MEX orbit on the Martian Moon ephemerides by using images of the moons taken by the camera (SRC) onboard MEX. We obtain estimates of the masses of Phobos and Deimos with formal errors that are comparable or better than previous estimates from MGS and Mars Odyssey. By using our accurate orbits of MEX, we also estimate the second order coefficients of the gravity field of Phobos, which can be used as a constraint on the internal mass distribution of Phobos.
DE: 1221 Lunar and planetary geodesy and gravity (5417, 5450, 5714, 5744, 6019, 6250)
DE: 6225 Mars
DE: 6230 Martian satellites
SC: Planetary Sciences [P]
MN: 2007 Fall Meeting