Open AccessFlares at Earth and Mars: An Ionospheric Escape Mechanism?
Author(s) -
Mendillo M.,
Erickson P. J.,
Zhang S.R.,
Mayyasi M.,
Narvaez C.,
Thiemann E.,
Chamberlain P.,
Andersson L.,
Peterson W.
Publication year - 2018
Publication title -
space weather
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.254
H-Index - 56
ISSN - 1542-7390
DOI - 10.1029/2018sw001872
Subject(s) - ionosphere , mars exploration program , thermosphere , martian , atmospheric escape , atmosphere (unit) , atmosphere of mars , solar flare , atmospheric sciences , physics , astrobiology , environmental science , astronomy , meteorology
Solar flares are nature's active experiment upon a planet's upper atmosphere and ionosphere. Observed effects at Earth are consistent with a “second sunrise” scenario that produces changes in electron density, electron temperature, and plasma dynamics. A solar active region in September 2017 provoked ionospheric disturbances due to solar flares observed at Earth (6 September) and later at Mars (10 and 17 September). Incoherent scatter radar observations from the Millstone Hill Observatory showed a burst of upward diffusion due to electron temperature enhancements. We explore the companion possibility of flares causing upward drifts and plasma escape at Mars. Solar observations made by the EUV Monitor instrument on the Mars Atmosphere and Volatile EvolutioN (MAVEN) satellite are used to portray the time histories of irradiance changes to determine the “early” (onset to peak emission) and “late” (decay to background) time scales for these flares. During the initial phase of a flare (when photons ionize an atmosphere unmodified by flare heating), MAVEN was well above the ionosphere and thus no in situ data are available to asses this period of possible plasma escape. Estimates made using a simple terrestrial model for plasma drifts in the topside ionosphere suggest that escape rates can be enhanced at Mars at “early” times. The “late time” effects observed below 400 km 2 hr after the flare onset times did not reveal conclusive remnants of the proposed mechanism. No model of the Martian thermosphere‐ionosphere system has produced a self‐consistent simulation of solar flare effects upon Mars' upper atmosphere and ionosphere.