Origin of the extended Mars radar blackout of September 2017
journal contributionposted on 2019-05-29, 14:34 authored by B Sanchez-Cano, P-L Blelly, M Lester, O Witasse, M Cartacci, R Orosei, H Opgenoorth, R Lillis, F Leblanc, S Milan, P Conroy, N Floury, J Plane, A Cicchetti, R Noschese, A Kopf
The Mars Advanced Radar for Subsurface and Ionosphere Sounding (MARSIS) on board Mars Express, which operates between 0.1 and 5.5 MHz, suffered from a complete blackout for 10 days in September 2017 when observing on the nightside (a rare occurrence). Moreover, the Shallow Radar (SHARAD) onboard the Mars Reconnaissance Orbiter, which operates at 20 MHz, also suffered a blackout for 3 days when operating on both day and nightsides. We propose that these blackouts are caused by solar energetic particles (SEP) of few tens of keV and above associated with an extreme space weather event between 10 and 22 September 2017, as recorded by the MAVEN mission. Numerical simulations of energetic electron precipitation predict that a lower O2+ nighttime ionospheric layer of magnitude ~1010 m-3 peaking at ~90 km altitude is produced. Consequently, such a layer would absorb radar signals at HF frequencies and explain the blackouts. The peak absorption level is found to be at 70km altitude.
B.S.-C., M.L. and S.E.M. acknowledge support through STFC grant ST/N000749/1. ESA-ESTEC Faculty is gratefully acknowledged. F.L. was supported by CNES "Système Solaire” program and by the Programme National de Planétologie and by the ANR (ANR-09-BLAN-0223) and ANR MARMITE (ANR-13-BS05-0012-02). IPIM model simulations can be freely requested at IRAP391 CDPP web (http://transplanet.irap.omp.eu/). IPIM model is a property of CNRS. Part of this work and IPIM are supported by the Programme National Soleil Terre (PNST) from Institut des Sciences de l'Univers of Centre National de la Recherche Scientifique (INSU/CNRS) co-funded by CNES. This work was granted access to the HPC resources of CALMIP supercomputing center under the allocation 2017-P1520.
CitationJournal of Geophysical Research: Space Physics, 2019
Author affiliation/Organisation/COLLEGE OF SCIENCE AND ENGINEERING/Department of Physics and Astronomy
- AM (Accepted Manuscript)