How the solar wind interacts with Mars

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, [a paper published in the Journal of Geophysical Research–Space Physics examines] 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. [More at links]