2008/05/29 by Nicholas J. Tosca, Andrew H. Knoll, S. M. McLennan · 7 citations
Physics and Astronomy · Environmental Science · #Planetary Science and Exploration #Astro and Planetary Science #Isotope Analysis in Ecology
paper · doi:10.1126/science.1155432
openalex publication_date 2008/05/29 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/23
In situ and orbital exploration of the martian surface has shown that acidic, saline liquid water was intermittently available on ancient Mars. The habitability of these waters depends critically on water activity ( \batchmode \documentclass[fleqn,10pt,legalpaper]article \usepackageamssymb \usepackageamsfonts \usepackageamsmath \pagestyleempty \begindocument \(a_H2O\) \enddocument ), a thermodynamic measure of salinity, which, for terrestrial organisms, has sharply defined limits. Using constraints on fluid chemistry and saline mineralogy based on martian data, we calculated the maximum \batchmode \documentclass[fleqn,10pt,legalpaper]article \usepackageamssymb \usepackageamsfonts \usepackageamsmath \pagestyleempty \begindocument \(a_H2O\) \enddocument for Meridiani Planum and other environments where salts precipitated from martian brines. Our calculations indicate that the salinity of well-documented surface waters often exceeded levels tolerated by known terrestrial organisms.