Tosca Nicholas J, Knoll Andrew H, McLennan Scott M
Department of Organismic and Evolutionary Biology, Harvard University, Cambridge, MA 02138, USA.
Science. 2008 May 30;320(5880):1204-7. doi: 10.1126/science.1155432.
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 (aH2O), 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 aH2O 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.
对火星表面的实地和轨道探测表明，在古代火星上曾间歇性地存在过酸性盐水。这些水体的宜居性关键取决于水活性（aH₂O），这是一种盐度的热力学度量，对于地球生物来说，其具有明确的界限。利用基于火星数据对流体化学和盐类矿物学的限制，我们计算了子午线平原及其他有火星盐水盐分沉淀的环境中的最大水活性。我们的计算表明，有充分记录的地表水盐度常常超过已知地球生物所能耐受的水平。
