Strong plume fluxes at Mars observed by MAVEN: An important planetary ion escape channel

• Published in: Geophysical research letters Vol. 42; no. 21; pp. 8942 - 8950
• Main Authors: Dong, Y., Fang, X., Brain, D. A., McFadden, J. P., Halekas, J. S., Connerney, J. E., Curry, S. M., Harada, Y., Luhmann, J. G., Jakosky, B. M.
• Format: Journal Article
• Language: English
• Published: Washington Blackwell Publishing Ltd 16-11-2015; John Wiley & Sons, Inc
• Subjects: Atmosphere; atmospheric escape; Case studies; Channels; Convection; Coordinate systems; Data; Electric field; Electric fields; Evolution; Fluxes; Geophysics; Identification; ion escape; Ion flux; Ion fluxes; Ions; Mars; Mars atmosphere; Mars missions; Mars spacecraft; North Pole; Northern Hemisphere; plume; Plumes; polar plume; Populations; Solar wind; solar wind interaction; Spacecraft; Stellar mass; Sun; Upstream; Wind power generation; PN, Arctic, North Pole
• ISSN: 0094-8276; 1944-8007
• DOI: 10.1002/2015GL065346

We present observations by the Mars Atmosphere and Volatile EvolutioN (MAVEN) mission of a substantial plume‐like distribution of escaping ions from the Martian atmosphere, organized by the upstream solar wind convection electric field. From a case study of MAVEN particle‐and‐field data during one spacecraft orbit, we identified three escaping planetary ion populations: plume fluxes mainly along the upstream electric field over the north pole region of the Mars‐Sun‐Electric field (MSE) coordinate system, antisunward ion fluxes in the tail region, and much weaker upstream pickup ion fluxes. A statistical study of O+ fluxes using 3 month MAVEN data shows that the plume is a constant structure with strong fluxes widely distributed in the MSE northern hemisphere, which constitutes an important planetary ion escape channel. The escape rate through the plume is estimated to be ~30% of the tailward escape and ~23% of the total escape for > 25 eV O+ ions.
Key Points
Three escaping planetary ion populations near Mars are identified in MAVEN observations
MAVEN observed a substantial plume with strong escaping ion fluxes over the MSE north pole region
The plume contributes ~23% to the total >25 eV O+ escape of ~2 × 1024 s−1