title: Abundance and isotopic composition of gases in the martian atmosphere from the Curiosity rover.
abstract: Volume mixing and isotope ratios secured with repeated atmospheric measurements taken with the Sample Analysis at Mars instrument suite on the Curiosity rover are: carbon dioxide (CO2), 0.960(±0.007); argon-40 ((40)Ar), 0.0193(±0.0001); nitrogen (N2), 0.0189(±0.0003); oxygen, 1.45(±0.09) × 10(-3); carbon monoxide, < 1.0 × 10(-3); and (40)Ar/(36)Ar, 1.9(±0.3) × 10(3). The (40)Ar/N2 ratio is 1.7 times greater and the (40)Ar/(36)Ar ratio 1.6 times lower than values reported by the Viking Lander mass spectrometer in 1976, whereas other values are generally consistent with Viking and remote sensing observations. The (40)Ar/(36)Ar ratio is consistent with martian meteoritic values, which provides additional strong support for a martian origin of these rocks. The isotopic signature δ(13)C from CO2 of ~45 per mil is independently measured with two instruments. This heavy isotope enrichment in carbon supports the hypothesis of substantial atmospheric loss.
authors.affiliation: NASA Goddard Space Flight Center, Greenbelt, MD 20771, USA. paul.r.mahaffy@nasa.gov
authors.forename: Paul R
authors.initials: PR
authors.lastname: Mahaffy
authors.forename: Christopher R
authors.initials: CR
authors.lastname: Webster
authors.forename: Sushil K
authors.initials: SK
authors.lastname: Atreya
authors.forename: Heather
authors.initials: H
authors.lastname: Franz
authors.forename: Michael
authors.initials: M
authors.lastname: Wong
authors.forename: Pamela G
authors.initials: PG
authors.lastname: Conrad
authors.forename: Dan
authors.initials: D
authors.lastname: Harpold
authors.forename: John J
authors.initials: JJ
authors.lastname: Jones
authors.forename: Laurie A
authors.initials: LA
authors.lastname: Leshin
authors.forename: Heidi
authors.initials: H
authors.lastname: Manning
authors.forename: Tobias
authors.initials: T
authors.lastname: Owen
authors.forename: Robert O
authors.initials: RO
authors.lastname: Pepin
authors.forename: Steven
authors.initials: S
authors.lastname: Squyres
authors.forename: Melissa
authors.initials: M
authors.lastname: Trainer