Cosmic rays interaction with comets and its impact on cometary isotopic and chemical composition

Thursday, 17 December 2015
Poster Hall (Moscone South)
Guillaume Gronoff1, Romain Maggiolo2, Christopher J Mertens3, Vladimir Airapetian4, Johan De Keyser5, Gaƫl Cessateur5, Frederik Dhooghe5 and Herbert Gunell5, (1)Science Systems and Applications, Inc. Hampton, Hampton, VA, United States, (2)Belgian Institute for Space Aeronomy, Brussels, Belgium, (3)NASA Langley Research Center, Hampton, VA, United States, (4)NASA Goddard Space Flight Center, Greenbelt, MD, United States, (5)Belgisch Instituut voor Ruimte-Aeronomie, Brussel, Belgium
Comets contain the most pristine material in the solar system. However,
since their formation ~4.5 Gy ago, they have been altered by cosmic
rays. The galactic and solar cosmic rays have a broad spectrum of
energies and interact with the cometary surface and subsurface. While low energy
cosmic rays interact only with the cometary surface, the most energetic
cosmic rays deposit significant amount of energy down to tens of meters. This
interaction can modify the isotopic ratio in cometary ices and create
secondary compounds through radiolysis. We perform a theoretical
analysis of the effect of cosmic rays on cometary material. We modeled the
energy deposition of cosmic ray as a function of depth using a Geant4 application
modified to take into account the isotope creation process.
We analyze the consequences of the energy deposition on the isotopic
and chemical composition of cometary ices and discuss their implication
on the interpretation of cometary observations.