Bonn 2010 – wissenschaftliches Programm
EP 9.2: Vortrag
Mittwoch, 17. März 2010, 09:00–09:15, AKM
The internal structure of Phobos derived from Radio Science measurements — •Thomas Andert1, Martin Pätzold2, and Bernd Häusler1 — 1Institut für Raumfahrttechnik, Universität der Bundeswehr, München — 2Rheinisches Institut für Umweltforschung an der Universität zu Köln
The Mars Express spacecraft was successfully launched on 2 June 2003 and injected into orbit around Mars on 25 December 2003. The elliptical polar orbit of Mars Express allows close flybys at the Mars moon Phobos, the first close flybys since the flybys of Viking and Phobos 2 twenty years ago.
Mars Express performed two close flybys at Phobos in 2006 at 460 km and in 2008 at 275 km which resulted in a change of the orbit of Mars Express. The mass of Phobos was estimated from both flybys using the radio tracking data by evaluating the residual Doppler effect. The data of the second flyby provides a very small uncertainty of 0.3 % for the mass solution.
Mars Express will change its orbit in February 2010 which will allow a very close flyby at 62 km in March 2010. Here we report the results from the mass estimates of the flybys in 2006 and 2008 and the geophysical consequences for the internal structure of Phobos. In addition, simulation results about the feasibility of the low order coefficient J2 of the gravity field of Phobos at the very close flyby in March 2010 are shown.