Rosetta Dynamics

Rosetta is an ambitious ESA mission launched towards the comet 67P/Churyumov-Gerasimenko 2 March 2004. Comets are primordial objects holding clues to the early conditions in the Solar System. The Institute of Theoretical Astrophysics (ITA) is participatin g in the Radio Science Investigation (RSI) of the mission, aimed at determining the mass, shape, structure and composition of the comet's nucleus by interpreting the radio science signals from the Rosetta spacecraft in orbit about the nucleus and from a l ander on the surface of the nucleus. In preparation for this mission, ITA has been involved in observing the comet with the Nordic Optical Telescope on La Palma and improving our knowledge of the orbit of the comet. An orbit determination program is under development for ultra-precise tracking of the spacecraft and has already given very promising results. Theoretical and numerical studies of stable orbits about a comet nucleus have been performed. This work, partly funded by the Research Council of Norwa y, has resulted in three Master Theses and two Ph.D theses. The work will now be continued and extended with applications to data from the Rosetta spacecraft, primarily through one postdoc position. The orbit determination program will be further develope d and tested with tracking data from Rosetta flybys of the Earth and Mars in 2005 and 2007. Simulations are also planned of the orbiter phase of the mission. This includes studies of the stability of the orbiter's motion around the comet nucleus under the influence of the gravitational field of an irregularly shaped, rotating nucleus, outgassing from the nucleus and radiation pressure from the Sun.