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 × 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.
Highlights
Planetary interiors record their formation history and influence surface environments through volcanic and tectonic activities
Isotopic compositions of Ar, Kr, and Xe in the Martian atmosphere have been measured in situ by Viking and Curiosity (Atreya et al, 2013; Conrad et al, 2016) and recovered from Martian meteorites (Smith et al, 2020, and references therein)
While forming a dense primordial atmosphere is relatively easy for an Earth-sized planet, it is possible for a Mars-sized planet only under some specific conditions as we show below
Summary
Planetary interiors record their formation history and influence surface environments through volcanic and tectonic activities. Isotopic compositions of Ar, Kr, and Xe in the Martian atmosphere have been measured in situ by Viking and Curiosity (Atreya et al, 2013; Conrad et al, 2016) and recovered from Martian meteorites (Smith et al, 2020, and references therein). Those heavy noble gas isotopes have been used to constrain atmospheric evolution in the distant past (>1 Ga, Pepin, 1991, 1994; Slipski and Jakosky, 2016; Jakosky et al, 2017; Kurokawa et al, 2018).
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