Variations of polar CO2 caps during the first Martian year of FREND onboard TGO

Fine Resolution Epithermal Neutron Detector (FREND) is an instrument onboard ExoMars’ Trace Gas Orbiter (TGO). It uses neutron measurements to detect hydrogen (and thus water) variations in the shallow subsurface of the Martian soil. In case of sub-polar regions, it is quite sensitive to the thickness of seasonal deposition of CO₂, which it well-sees in neutrons, as “dry” layer on top of the hydrogen-rich polar permafrost soil.

This presentation is aimed to give a first look at variations of seasonal depositions of Carbone dioxide at winter vs summer seasons on Mars. Similar studies have been performed by neutron instruments earlier, however FREND’s major advantage is its much better spatial resolution: by shielding from the neutron flux coming from off-nadir directions, the instrument’s spatial resolution is improved down to a 60-200 km diameter spot. The orbiter’s inclination is currently 74 deg, so the experiment is capable to observe the rim of the polar permafrost northern and southern regions with seasonal coverages of atmospheric Carbone dioxide over them.

We re-define and improve the shape of polar CO₂ caps boundaries and the column density of seasonal deposits thanks to improved spatial resolution and present data of FREND’s first Martian year of observations of high Martian latitudes.