The study considered several forces and found that the one shown here, the VxB “pick-up” force, is largest for most of the space around Mars. Credit: Halekas et al., 2017, Figure 6g
Source: Journal of Geophysical Research: Space Physics

Mars, without a strong internal dipole magnetic field, is a place where the supersonic solar wind directly contacts the planet’s upper atmosphere. Using a large set of data from the Mars Atmosphere and Volatile EvolutioN (MAVEN) mission, Halekas et al. [2017] examine some properties of the solar wind in that interaction region, especially velocity distributions that might lead to plasma waves. The paper discusses this effect, plus provides a calculation of the large-scale force terms and their relationship to possible planetary ion loss. The conclusion isn’t surprising: the VxB “pick-up” force is largest and should dominate planetary ion loss. It’s nice to see the comparison with other terms in this robust combination of case studies and statistical analysis.

Citation: Halekas, J. S., et al. [2017]. Flows, fields, and forces in the Mars-solar wind interaction. Journal of Geophysical Research: Space Physics, 122, 11,320–11,341.

—Mike Liemohn, Editor-in-Chief, JGR: Space Physics

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