As part of the Biology and Mars Experiment (BIOMEX; ILSRA 2009-0834), samples of the lichen Circinaria gyrosa were placed on the exposure platform EXPOSE-R2, on the International Space Station (ISS) and exposed to space and to a Mars-simulated environment for 18 months (2014–2016) to study: (1) resistance to space and Mars-like conditions and (2) biomarkers for use in future space missions (Exo-Mars). When the experiment returned (June 2016), initial analysis showed rapid recovery of photosystem II activity in the samples exposed exclusively to space vacuum and a Mars-like atmosphere. Significantly reduced recovery levels were observed in Sun-exposed samples, and electron and fluorescence microscopy (transmission electron microscope and field emission scanning electron microscope) data indicated that this was attributable to the combined effects of space radiation and space vacuum, as unirradiated samples exhibited less marked morphological changes compared with Sun-exposed samples. Polymerase chain reaction analyses confirmed that there was DNA damage in lichen exposed to harsh space and Mars-like environmental conditions, with ultraviolet radiation combined with space vacuum causing the most damage. These findings contribute to the characterization of space- and Mars-resistant organisms that are relevant to Mars habitability.

中文翻译：

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在国际空间站外的EXPOSE-R2设施上进行太空飞行后，地衣的生命力：生物学和火星实验的结果。

作为生物学和火星实验（BIOMEX; ILSRA 2009-0834）的一部分，地衣圆环回的样本被放置在国际空间站（ISS）的曝光平台EXPOSE-R2上，并在太空和火星模拟的环境中暴露了18个月（2014-2016年），以研究：（1）对太空和类似火星的抵抗力条件和（2）用于未来太空任务的生物标记物（Exo-Mars）。当实验返回时（2016年6月），初步分析表明，仅暴露于太空真空和类似火星的气氛的样品中光系统II活性迅速恢复。在暴露于阳光下的样品中回收率显着降低，并且电子和荧光显微镜（透射电子显微镜和场发射扫描电子显微镜）的数据表明，这归因于空间辐射和空间真空的共同作用，因为未辐照的样品与暴露于阳光的样品相比，其形态学变化较小。聚合酶链反应分析证实，暴露于恶劣空间和类似火星环境条件的地衣中存在DNA损伤，其中紫外线辐射与空间真空相结合造成的损伤最大。这些发现有助于表征与火星的可居住性相关的耐太空和耐火星的生物。