Premium
Enhanced O 2 + loss at Mars due to an ambipolar electric field from electron heating
Author(s) -
Ergun R. E.,
Andersson L. A.,
Fowler C. M.,
Woodson A. K.,
Weber T. D.,
Delory G. T.,
Andrews D. J.,
Eriksson A. I.,
McEnulty T.,
Morooka M. W.,
Stewart A. I. F.,
Mahaffy P.R.,
Jakosky B. M.
Publication year - 2016
Publication title -
journal of geophysical research: space physics
Language(s) - English
Resource type - Journals
eISSN - 2169-9402
pISSN - 2169-9380
DOI - 10.1002/2016ja022349
Subject(s) - ambipolar diffusion , mars exploration program , ionosphere , ion , atomic physics , electric field , electron , dissociative recombination , solar wind , atmospheric escape , thermosphere , atmosphere of mars , plasma , physics , electron temperature , oxygen , materials science , atmospheric sciences , astrobiology , geophysics , chemistry , martian , nuclear physics , recombination , biochemistry , quantum mechanics , gene
Recent results from the MAVEN Langmuir Probe and Waves instrument suggest higher than predicted electron temperatures ( T e ) in Mars' dayside ionosphere above ~180 km in altitude. Correspondingly, measurements from Neutral Gas and Ion Mass Spectrometer indicate significant abundances of O 2 + up to ~500 km in altitude, suggesting that O 2 + may be a principal ion loss mechanism of oxygen. In this article, we investigate the effects of the higher T e (which results from electron heating) and ion heating on ion outflow and loss. Numerical solutions show that plasma processes including ion heating and higher T e may greatly increase O 2 + loss at Mars. In particular, enhanced T e in Mars' ionosphere just above the exobase creates a substantial ambipolar electric field with a potential ( e Φ) of several k B T e , which draws ions out of the region allowing for enhanced escape. With active solar wind, electron, and ion heating, direct O 2 + loss could match or exceed loss via dissociative recombination of O 2 + . These results suggest that direct loss of O 2 + may have played a significant role in the loss of oxygen at Mars over time.