Solar wind ENA precipitation in the Martian atmosphere: Monte Carlo simulation results

Since Mars has an extended hydrogen corona, solar wind protons can charge
exchange with the atomic constituents to become energetic hydrogen atoms,
also called "energetic neutral atoms (ENAs)". These ENAs can
access the Martian atmosphere unhindered by the induced magnetosphere and
crustal fields and are slowed by collisions until they are either turned
away from Mars or absorbed by the Martian atmosphere. The manuscript
(Sorgi Johann et al. ) calibrates a model of ENA precipitation using MAVEN
spacecraft data and quantifies the hydrogen imparted by the solar wind
over a decade. The model results used in that paper are produced by ASPEN,
a test particle model that calculates energy deposited in an atmosphere
[Jolitz et al. 2017]. This dataset includes the logged positions, types,
and species impacted in modeled collisions, as well as the positions of
simulated particles when they cross a predefined grid. This was used to
build 3D histograms of energy deposition and 3D fluxes as a function of
altitude.