Magnesium sulphate salts and the history of water on Mars.

摘要: Recent reports of ∼30 wt% sulphate within saline sediments on Mars1,2—probably occurring in hydrated form3—suggest a role for sulphates accounting equatorial H2O observed global survey by the Odyssey spacecraft4. Among salt hydrates likely to be present3, those MgSO4·nH2O series have many hydration states. Here we report exposure several these phases varied temperature, pressure and humidity constrain their possible contents under martian surface conditions. We found that crystalline structure content are dependent temperature–pressure history, an amorphous phase with slow dehydration kinetics forms at <1% relative humidity, equilibrium calculations may not reflect true H2O-bearing potential soils. Mg salts can retain sufficient explain portion observations5. Because system sensitive temperature they reveal much about history water Mars. However, ease transformation implies collected Mars will returned Earth unmodified, accurate situ analysis is imperative.