Charged Particle Environment on Mars – One Mars Year of MSL/RAD Measurements

Thursday, 17 December 2015
Poster Hall (Moscone South)
Bent Ehresmann1, Don Hassler1, Cary J Zeitlin2, Jan Kohler3, R F Wimmer-Schweingruber3, David E Brinza4, Scot CR Rafkin1, Gunther Reitz5, Jan Kristoffer Appel3, Jingnan Guo3, Henning Lohf3, Soenke Burmeister6, Daniel Matthiae5, Stephan I Böttcher3, Eckart Boehm3 and Cesar Martin-Garcia3, (1)Southwest Research Institute Boulder, Boulder, CO, United States, (2)Southwest Research Institute Boulder, Earth, Oceans & Space Department, Boulder, CO, United States, (3)University of Kiel, Kiel, Germany, (4)Jet Propulsion Laboratory, Pasadena, CA, United States, (5)German Aerospace Center DLR Cologne, Cologne, Germany, (6)Christian-Albrechts-Universität zu Kiel, Institute for Experimental and Applied Physics, Extraterrestrial Physics, Kiel, Germany
The Mars Science Laboratory's Radiation Assessment Detector (MSL/RAD) has been conducting measurements of the ionizing radiation field on the Martian surface since August 2012. This field is mainly dominated by Galactic Cosmic Rays (GCRs) and their interactions with the atoms in the atmosphere and soil. This yields a radiation environment consisting of a wide variety of particles and energies which, at high energies, is dominated by charged particles, e.g., ions, and their isotopes, electrons, and others. Over the course of the first Martian year (~2 Earth years) of the MSL mission, the radiation field was mainly modulated by two influences: the seasonal pressure cycle at Gale crater; and the variation of the impeding GCR flux due to changes in the solar activity. Here, we present charged particle fluxes measured over a 1000 days and analyze how the more-abundant ion species vary over that time frame. A second major influence to the radiation field can be the contribution from Solar Energetic Particle (SEP) events. In particular, the Martian surface proton flux can be enhanced by orders of magnitude on short time scales during strong events. Here, we present measurements of the proton fluxes during the SEP events MSL/RAD has so far directly measured in Gale crater.