3D Direct Simulation Monte Carlo Modeling of the Spacecraft Environment of Rosetta

Thursday, 18 December 2014
Andre Michel Bieler1, Valeriy Tenishev1, Nicolas Fougere1, Tamas I Gombosi1, Kenneth C Hansen1, Michael R Combi1, Zhenguang Huang1, Xianzhe Jia1, Gabor Toth1, Kathrin Altwegg2, Peter Wurz2, Annette Jäckel2, Lena Le Roy2, Sébastien Gasc2, Ursina Calmonte2, Martin Rubin2, Chia-yu Tzou2, Myrtha Hässig3, Stephen Fuselier3, Johan De Keyser4, Jean-Jacques Berthelier5, Urs A. Mall6, Henri Rème7, Björn Fiethe8 and Hans Balsiger2, (1)University of Michigan, Ann Arbor, MI, United States, (2)University of Bern, Bern, Switzerland, (3)Southwest Research Institute San Antonio, San Antonio, TX, United States, (4)Belgian Institute for Space Aeronomy, Brussels, Belgium, (5)LATMOS Laboratoire Atmosphères, Milieux, Observations Spatiales, Paris Cedex 05, France, (6)Max Planck Institute for Solar System Research, Katlenburg-Lindau, Germany, (7)IRAP, Institut de Recherche en Astrophysique et Planétologie, Toulouse, France, (8)Technical University of Braunschweig, Braunschweig, Germany
The European Space Agency’s Rosetta mission is the first to escort a comet over an extended time as the comet makes its way through the inner solar system. The ROSINA instrument suite consisting of a double focusing mass spectrometer, a time of flight mass spectrometer and a pressure sensor, will provide temporally and spatially resolved data on the comet’s volatile inventory.

The effect of spacecraft outgassing is well known and has been measured with the ROSINA instruments onboard Rosetta throughout the cruise phase. The flux of released neutral gas originating from the spacecraft cannot be distinguished from the cometary signal by the mass spectrometers and varies significantly with solar illumination conditions. For accurate interpretation of the instrument data, a good understanding of spacecraft outgassing is necessary. In this talk we present results simulating the spacecraft environment with the Adaptive Mesh Particle Simulator (AMPS) code. AMPS is a direct simulation monte carlo code that includes multiple species in a 3D adaptive mesh to describe a full scale model of the spacecraft environment. We use the triangulated surface model of the spacecraft to implement realistic outgassing rates for different areas on the surface and take shadowing effects in consideration. The resulting particle fluxes are compared to the measurements of the ROSINA experiment and implications for ROSINA measurements and data analysis are discussed. Spacecraft outgassing has implications for future space missions to rarefied atmospheres as it imposes a limit on the detection of various species.