March: a segmentation network identifies ten years of O2+ ion beams removed from the atmosphere in MAVEN data

A U-Net model identified in a decade of observations of the MAVEN probe the energy beams of O2+ ions that escape from Mars, and showed that the solar wind is the main engine.

The solar wind accelerates some of the ions in the Martian ionosphere until they are expelled into space, a mechanism that largely contributes to the planet's loss of atmosphere. A team of fourteen researchers trained a U-Net-type image segmentation network to isolate, in ten years of measurements by NASA's MAVEN probe, a precise population of these leaking ions: the energy beams of O2+. Each episode detected was then used for a statistical analysis of their properties on a planetary scale.

The electric field of the solar wind in the driver's seat

These beams appear almost everywhere around Mars, with a clear preference for the hemisphere where the convective electric field of the solar wind points outwards from the planet, which points to this field as a major player in their formation. In the induced magnetic tail, a Hall field can provide them with additional energy. Their characteristics depend above all on the conditions of the solar wind upstream, with no visible effect of the Sun's extreme ultraviolet radiation.

On a frequency-weighted average, the measured fluxes are similar to previous estimates of the ion plume, but during the episodes themselves they are significantly higher, a detail that can be captured by the event-based approach. The authors also see this as evidence that deep learning can identify transient plasma populations in spacecraft data.