Origin of the Extended Mars Radar Blackout of September 2017

Journal
Date Issued
2019
Author(s)
Sánchez-Cano, Beatriz
•
Blelly, Pierre-Louis
•
Lester, Mark
•
Witasse, Olivier
•
•
•
Opgenoorth, Hermann
•
Lillis, Robert
•
Leblanc, François
•
Milan, Stephen E.
•
Conroy, Philip
•
Floury, Nicolas
•
Plane, John M. C.
•
•
•
Kopf, Andrew J.
DOI
Abstract
The Mars Advanced Radar for Subsurface and Ionosphere Sounding (MARSIS) onboard 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 three days when operating on both dayside and nightside. We propose that these blackouts are caused by solar energetic particles of few tens of keV and above associated with an extreme space weather event between 10 and 22 September 2017, as recorded by the Mars Atmosphere and Volatile EvolutioN (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 high frequencies and explain the blackouts. The peak absorption level is found to be at 70-km altitude.
Volume
124
Issue
6
Start page
4556
Uri
Url
Issn Identifier
2169-9380
Ads BibCode
2019JGRA..124.4556S
Rights
open.access
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