MAVEN observations of initial ion acceleration in the Martian ionosphere
- 1Space Sciences Laboratory, University of California Berkeley, Berkeley, United States of America (gwen.hanley@berkeley.edu)
- 2Department of Physics and Astronomy, West Virginia University, Morgantown, United States of America
Though ion escape to space is an important mechanism for atmospheric loss on Mars, the processes that accelerate ions to escape velocity have not been identifed and quantified. The lowest altitude where suprathermal planetary ions appear is an important source region for ion escape, where electromagnetic forces and waves begin to energize ions to escape velocity. We have conducted a statistical study of O2+ distribution functions measured by Mars Volatile EvolutioN SupraThermal And Thermal Ion Composition (MAVEN-STATIC) in order to identify this source region for Martian ion escape. We have fit Maxwellians to each measured O2+ distribution function in order to identify distributions containing a suprathermal component. Suprathermal ions appear just above the exobase region at all solar zenith angles, but Maxwellian ion distributions persist to higher altitudes near the terminator than on the dayside or the nightside. We also investigated the effects of crustal magnetism, finding that crustal fields protect planetary plasma from energization on the dayside and enhance energization on the nightside.
How to cite: Hanley, G., Fowler, C., McFadden, J., Mitchell, D., and Curry, S.: MAVEN observations of initial ion acceleration in the Martian ionosphere, Europlanet Science Congress 2022, Granada, Spain, 18–23 Sep 2022, EPSC2022-277, https://doi.org/10.5194/epsc2022-277, 2022.
