Rothschild L J
Solar System Exploration Branch, NASA-Ames Research Center, Moffett Field, California 94035, USA.
Icarus. 1990;88:246-60. doi: 10.1016/0019-1035(90)90188-f.
The prospect of life on Mars today is daunting. Especially problematic for a potential life form is a lack of water, particularly in a liquid state; extremely cold temperatures; ultraviolet and ionizing radiation; and soil oxidants. Yet, "oases" where life might persist have been suggested to occur in rocks (in analogy with endolithic microorganisms described from deserts around the world), in polar ice caps (in analogy with snow and ice algae) and in possible volcanic regions (in analogy with chemoautotrophs living in deep sea hydrothermal vents); all are critically examined. Microorganisms are known to be able to survive in salt crystals, and recently it has been shown that organisms can metabolize while encrusted in evaporites. Because evaporites are thought to occur on Mars and can attenuate light in the UV range while being far more transparent to radiation useful for photosynthesis (400-700 nm), and because of the properties of these "endoevaporitic" organisms, I propose that such communities provide a new model system for studying potential life on Mars. On the basis of this model, I suggest possibilities for site selection for future exobiological experiments on Mars.
如今，火星上存在生命的前景令人望而却步。对于潜在的生命形式而言，尤其成问题的是缺水，特别是液态水的缺乏；极低的温度；紫外线和电离辐射；以及土壤氧化剂。然而，有人提出在岩石中（类似于世界各地沙漠中发现的石内微生物）、极地冰盖中（类似于冰雪藻类）以及可能的火山区域（类似于生活在深海热液喷口的化学自养生物）可能存在生命得以存续的“绿洲”；所有这些都受到了严格审视。已知微生物能够在盐晶体中存活，最近还发现生物体在被包裹于蒸发岩中时仍能进行新陈代谢。由于据信火星上存在蒸发岩，它们能在紫外线范围内衰减光线，而对光合作用有用的辐射（400 - 纳米）则具有更高的透明度，并且鉴于这些“内蒸发岩”生物的特性，我认为这样的群落为研究火星上的潜在生命提供了一个新的模型系统。基于这个模型，我提出了未来在火星上进行外星生物学实验的选址可能性。
