The search for life beyond Earth has focused on Mars and the icy moons Europa and Enceladus, all of which are considered a safe haven for life due to evidence of current or past water. The surface of Venus, on the other hand, has extreme conditions that make it a nonhabitable environment to life as we know it. This is in contrast, however, to its cloud layer, which, while still an extreme environment, may prove to be a safe haven for some extreme forms of life similar to extremophiles on Earth. We consider the venusian clouds a habitable environment based on the presence of (1) a solvent for biochemical reactions, (2) appropriate physicochemical conditions, (3) available energy, and (4) biologically relevant elements. The diversity of extreme microbial ecosystems on Earth has allowed us to identify terrestrial chemolithoautotrophic microorganisms that may be analogs to putative venusian organisms. Here, we hypothesize and describe biological processes that may be performed by such organisms in the venusian clouds. To detect putative venusian organisms, we describe potential biosignature detection methods, which include metal-microbial interactions and optical methods. Finally, we describe currently available technology that can potentially be used for modeling and simulation experiments.

中文翻译：

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金星云的外星生物学：通过陆地模型和检测方法对可居住性的新见解

寻找地球以外的生命的重点是火星和冰冷的卫星欧罗巴和土卫二，由于当前或过去有水的证据，所有这些都被认为是生命的避风港。另一方面，金星表面的极端条件使其成为我们所知的不适合生命生存的环境。然而，这与其云层形成鲜明对比，云层虽然仍然是一个极端环境，但可能被证明是某些极端生命形式的避风港，类似于地球上的极端微生物。我们认为金星云是一个可居住的环境，基于 (1) 生化反应的溶剂、(2) 适当的物理化学条件、(3) 可用能量和 (4) 生物相关元素的存在。地球上极端微生物生态系统的多样性使我们能够识别可能类似于假定的金星生物的陆地化能自养微生物。在这里，我们假设并描述了这些生物在金星云中可能进行的生物过程。为了检测推定的金星生物，我们描述了潜在的生物特征检测方法，包括金属-微生物相互作用和光学方法。最后，我们描述了当前可用于建模和仿真实验的可用技术。其中包括金属-微生物相互作用和光学方法。最后，我们描述了当前可用于建模和仿真实验的可用技术。其中包括金属-微生物相互作用和光学方法。最后，我们描述了当前可用于建模和仿真实验的可用技术。