The imprint of atmospheric evolution in the D/H of Hesperian clay minerals on Mars

• DOI: 10.1126/science.1260291
• Publication Date: 2014-12-17T05:40:22Z
• Authors: P. R. Mahaffy; C. R. Webster; J. C. Stern; A. E. Brunner; S. K. Atreya; P. G. Conrad; S. Domagal-Goldman; J. L. Eigenbrode; G. J. Flesch; L. E. Christensen; H. B. Franz; C. Freissinet; D. P. Glavin; J. P. Grotzinger; J. H. Jones; L. A. Leshin; C. Malespin; A. C. McAdam; D. W. Ming; R. Navarro-Gonzalez; P. B. Niles; T. Owen; A. A. Pavlov; A. Steele; M. G. Trainer; K. H. Williford; J. J. Wray
• Keywords: Hesperian; Achondrite

The deuterium-to-hydrogen (D/H) ratio in strongly bound water or hydroxyl groups ancient martian clays retains the imprint of formation these minerals. Curiosity's Sample Analysis at Mars (SAM) experiment measured thermally evolved and hydrogen gas released between 550° 950°C from samples Hesperian-era Gale crater smectite to determine this isotope ratio. D/H value is 3.0 (±0.2) times standard mean ocean water. ~3-billion-year-old mudstone, which half that present atmosphere but substantially higher than expected very early Mars, indicates an extended history escape desiccation planet.