Authors: Andert Tom P., P㳺old M., H㴳ler B., and Tellmann S.
%F: AA(Institut fr Raumfahrttechnik und Weltraumnutzung, Universitã² der Bundeswehr Mnchen, Germany), AB(Rheinisches Institut fr Umweltforschung, Abteilung Planetenforschung (RIU-PF), an der Universitã² zu Kíµ®í¼¬ Germany), AC(Institut fr Raumfahrttechnik und Weltraumnutzung, Universitã² der Bundeswehr Mnchen, Germany), AD(Rheinisches Institut fr Umweltforschung, Abteilung Planetenforschung (RIU-PF), an der Universitã² zu Kíµ®í¼¬ Germany)
Title: The Observed Gravity Field of Phobos and an Extrapolation of its Interior
Abstract: The mass of the Mars moon Phobos has been determined by spacecraft close flybys, by solving for the Martian gravity field and by the analysis of secular orbit perturbations. The absolute value and accuracy is sensitive on the actuality of the Phobos ephemeris, the accuracy of the spacecraft orbit, other perturbing forces acting on the spacecraft and the resolution of the Martian gravity field besides the measurement accuracy of the radio tracking data. The mass value and its error improved from spacecraft mission to mission or from the modern analysis of ``old'' tracking data. The global geophysical parameters total mass GM = (0.7071 0.0063) x10-3 km3 s2 , C20 , and the bulk density (1876 20) kgm3 of the Mars moon Phobos derived from the close Mars Express flyby in 2010 are consistent with a loosely consolidated body of a grossly inhomogeneous mass distribution. The modelling of the moon's interior by a randomly selected mass distribution of given porosity and water ice content let the simulated C20 decrease with increasing porosity and water ice content indicating an increasingly inhomogeneous mass distribution. This gives further evidence that Phobos re-accreted in orbit from a debris disk and is not a captured asteroid. The current knowledge of Phobos gravity field obtained from different spacecraft observations will be reviewed and the results from the very close flyby performed by Mars Express in 2010 will be presented.
Keywords: analysis, data, Mars, Phobos, spacecraft
Journal: American Astronomical Society, DPS meeting #45, #313.01
Volume: 45
Year: 2013
Bibliogaphic Code: 2013DPS....4531301A
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