Energetic Particle Showers Over Mars from Comet C/2013 A1 Siding Spring
journal contributionposted on 2019-07-25, 14:27 authored by B Sanchez-Cano, O Witasse, M Lester, A Rahmati, R Ambrosi, R Lillis, F Leblanc, P-L Blelly, M Costa, S Cowley, J Espley, S Milan, J Plaut, C Lee, D Larson
This paper is a phenomenological description of multispacecraft observations of energetic particles caused by the close flyby of comet C/2013 A1 Siding Spring with Mars on 19 October 2014. This is the first time that cometary energetic particles have been observed at Mars. The Mars Atmosphere and Volatile EvolutioN (MAVEN)‐solar energetic particle (SEP) and the Mars Odyssey‐High Energy Neutron Detector (HEND) instruments recorded evidence of precipitating particles, which are likely O+ pickup ions, during the ~10 hr that Mars was within the region of the comet's coma. O+ pickup ions were also detected several hours after, although whether their origin is the comet or space weather is not conclusive. We discuss the possible origin of those particles and also the cause of an additional shower of energetic particles that HEND observed between 22 and 35 hr after the comet's closest approach, which may be related to dust impacts from the comet's dust tail. An O+ pickup ion energy flux simulation is performed with representative solar wind and cometary conditions, together with a simulation of their energy deposition profile in the atmosphere of Mars. Results indicate that the O+ pickup ion fluxes observed by SEP were deposited in the ionosphere around 105 to 120 km altitude, and they are compared with precomet flyby estimations of cometary pickup ions. The comet's flyby deposited a significant fluence of energetic particles into Mars' upper atmosphere, at a similar level to a large space weather event.
B. S. -C., M. L., S. W. H. C., and S. E. M. acknowledge support through STFC grant ST/N000749/1. Authors acknowledge Jingnan Guo and Robert F. Wimmer-Schweingruber from Christian-Albrechts-University in Kiel (Germany), Ed Thiemann from University of Colorado (United States), and Jennifer Alyson Carter from University of Leicester (United Kingdom) for useful discussions. All data can be downloaded from the NASA PDS archive and from the MAVEN Science Data Center (https://lasp.colorado.edu/ maven/sdc/public/). Part of the data analysis was performed with the help of the AMDA science analysis system provided by the Centre de Données de la Physique des Plasmas (CDPP) supported by CNRS, CNES, Observatoire de Paris, and Université Paul Sabatier, Toulouse. The latest trajectory of the comet can be found at ftp://ssols01.esac.esa.int/pub/ data/SPICE/MEX/kernels/spk/C2013A1_ S105_MERGED.BSP; in addition, a webbased geometry service is available for the comet trajectory at http://spice.esac. esa.int/webgeocalc/, and a 3-D visualization of the encounter made with the SPICE-enhanced Cosmographia tool can be found at https://www.youtube.com/ watch?v=dhI8VxZX1dA. Support from the ESA-ESTEC Faculty is acknowledged.
CitationJournal of Geophysical Research: Space Physics, 2018, 123(10), pp. 8778-8796
Author affiliation/Organisation/COLLEGE OF SCIENCE AND ENGINEERING/Department of Physics and Astronomy
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