HR: 1340h
AN: G43A-0802    [Abstracts]
TI: Mass and internal structure of Phobos from close flybys by Mars-Express
AU: * Andert, T P
EM: andert@geo.uni-koeln.de
AF: Institut f\"ur Geophysik und Meteorologie, Universit\"at zu K\"oln,, Albertus-Magnus-Platz, K\"oln, D-50923 Germany
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, D-50923 Germany
AU: Lainey, V
EM: valeryl@oma.be
AF: Royal Observatory of Belgium, Ringlaan 3, Brussel, 1180 Belgium
AU: Rosenblatt, P
EM: pascal.rosenblatt@oma.be
AF: Royal Observatory of Belgium, Ringlaan 3, Brussel, 1180 Belgium
AU: Dehant, V
EM: v.dehant@oma.be
AF: Royal Observatory of Belgium, Ringlaan 3, Brussel, 1180 Belgium
AU: Barriot, J
AF: Observatoire Midi-Pyr\'en\'ees, GRGS/CNES, 14 Ave Edouard Belin, Toulouse, F-31401 France
AB: Several close encounters of Phobos by Mars Express spacecraft are scheduled for 2005. This will give us the opportunity to study its mass, internal structure and particularly the assumption of a constant density. Using the perturbations induced on MEX motion by Phobos irregular shape, one can fit its first gravitational coefficients as $J_2$ and $C_{22}$ and compare them with computed harmonics based on the shape and assumed constant density. We present a simulation of this method. A first software called GINS (primary developed by CNES) is used to represent MEX motion just before the close encounter. A second software has been developed to fit the Phobos gravitational potential, using the observed velocity perturbations on MEX. It is noteworthy that it will be the first direct observational derivation of Phobos' internal structure.
DE: 1299 General or miscellaneous
SC: Geodesy [G]
MN: 2004 AGU Fall Meeting