Mars’ atmospheric neon suggests volatile-rich primitive mantle

• Published in: Icarus (New York, N.Y. 1962) N.Y. 1962), 2021-12, Vol.370 (December), p.114685, Article 114685
• Main Authors: Kurokawa, Hiroyuki, Miura, Yayoi N., Sugita, Seiji, Cho, Yuichiro, Leblanc, François, Terada, Naoki, Nakagawa, Hiromu
• Format: Article
• Language: English
• Subjects: Atmospheres; Composition; Interiors; Mars; Planetary formation; Sciences of the Universe; Volcanism
• ISSN: 0019-1035; 1090-2643
• DOI: 10.1016/j.icarus.2021.114685

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 × 108 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. •We estimate the timescale for atmospheric loss of Martian Ne to be 60 to 100 Myrs.•The short lifetime suggests that Ne is being supplied by volcanism on current Mars.•The estimated mantle Ne abundance is more than 5-80 times higher than that of Earth.•Possible origins of abundant Ne include solar nebula gas and Mars’ building blocks.•Measurements of Ne isotopic ratio are crucial to understand the origins of Martian Ne.