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.  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. . Flows, fields, and forces in the Mars-solar wind interaction. Journal of Geophysical Research: Space Physics, 122, 11,320–11,341. https://doi.org/10.1002/2017JA024772
—Mike Liemohn, Editor-in-Chief, JGR: Space Physics