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EP: Fachverband Extraterrestrische Physik

EP 8: Planets and Small Bodies I

EP 8.6: Vortrag

Dienstag, 16. März 2010, 18:00–18:15, AKM

Rosetta at comet 67P/Churyumov-Gerasimenko: Spacecraft orbit modeling — •Matthias Hahn¹, Martin Pätzold¹, Silvia Tellmann¹, Jörg Selle², and Tom Andert² — ¹Rheinisches Institut für Umweltforschung, Abteilung Planetenforschung, Cologne, Germany — ²Institut für Raumfahrttechnik, Universität der Bundeswehr, Munich, Cologne

The Rosetta spacecraft has been successfully launched on 2nd March 2004 to its target comet 67P/Churyumov-Gerasimenko. The science objectives of the Rosetta Radio Science Investigations (RSI) experiment addresses fundamental geophysical aspects such as the mass and bulk density of the nucleus, its size and shape and its gravity field and internal structure. The radio carrier links between Rosetta spacecraft and the Earth will be used for these investigations. The perturbed motion of the spacecraft near the comet nucleus will cause Doppler frequency shifts of the transmitted radio carrier frequencies. These frequency shifts can be used to reconstruct precisely the flown orbit. In order to extract small changes of the carrier frequency, a prediction of the orbit is needed which includes best known estimates for all forces acting on the spacecraft. These forces are the nucleus gravity field, third body perturbations, the solar radiation pressure, the solar wind pressure, and the cometary outgassing, for example. From the differences between the predicted and observed frequency shifts it is then possible to determine iteratively low degree and order harmonic coefficients of the nucleus gravity field or the gas pressure force and the gas production rate from outgassing.