Mars' atmospheric neon suggests volatile-rich primitive mantle

TL;DR

Martian atmospheric neon levels indicate recent volcanic activity and a mantle richer in Ne than Earth's, providing insights into Mars's interior composition and formation history.

Contribution

This study links atmospheric neon measurements to Mars's volcanic activity and mantle composition, suggesting a volatile-rich interior and informing planetary formation models.

Findings

Martian atmospheric Ne suggests recent active volcanism.

Mars's mantle is richer in Ne than Earth's mantle.

Ne abundance implies efficient capture of solar nebular gases.

Abstract

Martian atmospheric neon (Ne) has been detected by Viking and also found as trapped gas in Martian meteorites, though its abundance and isotopic composition have not been well determined. Because the timescale of Ne loss via atmospheric escape estimated from recent measurements with MAVEN is short (0.6--1 $\times$ 10$^8$ years), the abundance and isotope composition of Martian atmospheric Ne reflect recent atmospheric gas supply mostly from volcanic degassing. Thus, it can serve as a probe for the volatile content of the interior. Here we show that the tentatively-informed atmospheric Ne abundance suggests recent active volcanism and the mantle being richer in Ne than Earth's mantle today by more than a factor of 5--80. The estimated mantle Ne abundance requires efficient solar nebular gas capture or accretion of Ne-rich materials such as solar-wind-implanted dust in the planet formation stage, both of which provide important constraints on the abundance of other volatile elements in the interior and the accretion history of Mars. More precise determination of atmospheric Ne abundance and isotopic composition by in situ analysis or Mars sample return is crucial for distinguishing the possible origins of Ne.