SETI Institute, Mountain View, California, USA.
Astrobiology. 2010 Oct;10(8):821-43. doi: 10.1089/ast.2009.0440.
Mars has undergone three main climatic stages throughout its geological history, beginning with a water-rich epoch, followed by a cold and semi-arid era, and transitioning into present-day arid and very cold desert conditions. These global climatic eras also represent three different stages of planetary habitability: an early, potentially habitable stage when the basic requisites for life as we know it were present (liquid water and energy); an intermediate extreme stage, when liquid solutions became scarce or very challenging for life; and the most recent stage during which conditions on the surface have been largely uninhabitable, except perhaps in some isolated niches. Our understanding of the evolution of Mars is now sufficient to assign specific terrestrial environments to each of these periods. Through the study of Mars terrestrial analogues, we have assessed and constrained the habitability conditions for each of these stages, the geochemistry of the surface, and the likelihood for the preservation of organic and inorganic biosignatures. The study of these analog environments provides important information to better understand past and current mission results as well as to support the design and selection of instruments and the planning for future exploratory missions to Mars.
火星在其地质历史上经历了三个主要的气候阶段，从一个富含水的时代开始，随后是一个寒冷和半干旱的时代，最后进入了现在干旱和极寒的沙漠条件。这些全球气候阶段也代表了行星可居住性的三个不同阶段：一个早期的、潜在可居住的阶段，当时存在我们所知的生命的基本要求（液态水和能量）；一个中间的极端阶段，当液态溶液变得稀缺或对生命极具挑战性；以及最近的阶段，在这个阶段，表面条件在很大程度上不适宜居住，除非在某些孤立的小生境中。我们对火星演化的理解现在足以将特定的陆地环境分配给这些时期中的每一个。通过对火星地球模拟物的研究，我们评估和限制了这些阶段的可居住条件、表面地球化学以及保存有机和无机生物特征的可能性。对这些模拟环境的研究为更好地理解过去和当前的任务结果以及支持未来火星探测任务的仪器设计和选择以及规划提供了重要信息。
