Abstract
Martian crustal magnetic fields influence the solar wind interaction
with Mars in a way that is not fully understood. In some locations,
crustal magnetic fields act as “mini-magnetospheres”, shielding the
planet’s atmosphere, while in other locations they act as channels for
enhanced energy input and particle escape. The net effect of this system
is not intuitively clear, but previous modeling studies have suggested
that crustal fields likely decrease global ion escape from Mars. In this
study we use data from the Mars Atmosphere and Volatile EvolutioN
(MAVEN) spacecraft to analyze how crustal magnetic fields influence both
global and local ion escape at Mars. We find that crustal fields only
increase ion escape if ions are assumed to be so unmagnetized that
closed magnetic fields only trap 35% or less of energized Oxygen ions.
In any other case, crustal fields decrease both global and local ion
escape by as much as 40% and 80%, respectively. This suggests that the
presence of crustal magnetic fields has had a moderate impact on
atmospheric ion loss throughout Martian history, potentially influencing
the planet’s atmospheric evolution and habitability.