First direct observations of atmospheric sputtering at Mars.

Billions of years ago, Mars' ability to sustain liquid water waned as the solar wind and radiation began to erode the atmosphere. Sputtering is an atmospheric escape process that may have been dominant during earlier epochs of our Sun according to isotopic evidence, but is difficult to detect under current solar conditions. Using over 9 years of data from the Mars Atmosphere and Volatile Evolution mission, we present the first observations of present-day sputtering in the martian upper atmosphere.

A Statistical Investigation of Factors Influencing the Magnetotail Twist at Mars.

The Martian magnetotail exhibits a highly twisted configuration, shifting in response to changes in polarity of the interplanetary magnetic field's (IMF) dawn-dusk ( ) component. Here, we analyze ∼6000 MAVEN orbits to quantify the degree of magnetotail twisting ( ) and assess variations as a function of (a) strong planetary crustal field location, (b) Mars season, and (c) downtail distance. The results demonstrate that is larger for a duskward (+ ) IMF orientation a majority of the time.