Research press release


Nature Geoscience

Martian brines could be oxygen-rich enough to support life



Vlada Stamenkovicたちは、分子状酸素が、火星表面近傍で予想されるさまざまな温度圧力条件下で、塩と水からなる液体の塩水にどの程度溶解し得るかを計算した。その結果、分子状酸素濃度は特に極地域で高いことが明らかになった。さらに、火星の表面下にある塩水には好気性生物を維持するのに十分な量の酸素を含む可能性があることが分かった。これらの知見によって、火星表面を調査している探査機が見つけた酸化した岩石が、どのようにして形成されたかについても説明できる可能性がある。

Briny waters just below the surface of Mars have the potential to hold enough molecular oxygen to support aerobic microbes and, in some cases, also simple animals like sponges, reports a paper published online this week in Nature Geoscience.

On Earth, aerobic, or oxygen-breathing, life evolved together with photosynthesis, which raised atmospheric oxygen levels. However, on Mars oxygen is scarce, with only trace amounts being produced by the light-induced breakdown of carbon dioxide. Thus, it was previously thought that molecular oxygen would not be capable of supporting life on the Red Planet.

Vlada Stamenkovic and colleagues calculate how much molecular oxygen could be dissolved in liquid brines composed of salt and water under the various pressure and temperature conditions expected to be found near the surface of Mars. They find that molecular oxygen concentrations are particularly high in the polar regions. Furthermore, some of the brines in the Martian subsurface could contain enough oxygen to support aerobic life. These findings may also explain how the oxidized rocks seen by rovers exploring Mars’ surface could have formed.

doi: 10.1038/s41561-018-0243-0


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