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Cold ion escape from the Martian ionosphere
Max Planck Inst Sonnensyst Forsch, D-37077 Gottingen, Germany..
Max Planck Inst Sonnensyst Forsch, D-37077 Gottingen, Germany..
Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
Swedish Inst Space Phys, S-89128 Kiruna, Sweden..
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2015 (English)In: Planetary and Space Science, ISSN 0032-0633, E-ISSN 1873-5088, Vol. 119, 92-102 p.Article in journal (Refereed) PublishedText
Abstract [en]

We here report on new measurements of the escape flux of oxygen ions from Mars by combining the observations of the ASPERA-3 and MARSIS experiments on board the European Mars Express spacecraft. We show that in previous estimates of the total heavy ion escape flow the contribution of the cold ionospheric outflow with energies below 10 eV has been underestimated. Both case studies and the derived flow pattern indicate that the cold plasma observed by MARSIS and the superthermal plasma observed by ASPERA-3 move with the same bulk speed in most regions of the Martian tail. We determine maps of the tailside heavy ion flux distribution derived from mean ion velocity distributions sampled over 7 years. If we assume that the superthermal bulk speed derived from these long time averages of the ion distribution function represent the total plasma bulk speed we derive the total tailside plasma flux. Assuming cylindrical symmetry we determine the mean total escape rate for the years 2007-2014 at 2.8 +/- 0.4 x 10(25) atoms/s which is in good agreement with model estimates. A possible mechanism to generate this flux can be the ionospheric pressure gradient between dayside and nightside.

Place, publisher, year, edition, pages
2015. Vol. 119, 92-102 p.
Keyword [en]
Mars, Ionosphere, Atmospheric escape, Plasma velocity distributions
National Category
Astronomy, Astrophysics and Cosmology
URN: urn:nbn:se:uu:diva-274449DOI: 10.1016/j.pss.2015.07.012ISI: 000367108700011OAI: oai:DiVA.org:uu-274449DiVA: diva2:896473
Swedish National Space Board
Available from: 2016-01-21 Created: 2016-01-21 Last updated: 2016-01-21Bibliographically approved

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Andrews, David
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