1 Biodiversity Research/Systematic Botany, University of Potsdam, Potsdam, Germany.
2 Radiation Biology, Institute of Aerospace Medicine, German Aerospace Center (DLR), Cologne, Germany.
Astrobiology. 2019 Feb;19(2):221-232. doi: 10.1089/ast.2018.1889.
As a part of the European Space Agency mission "EXPOSE-R2" on the International Space Station (ISS), the BIOMEX (Biology and Mars Experiment) experiment investigates the habitability of Mars and the limits of life. In preparation for the mission, experimental verification tests and scientific verification tests simulating different combinations of abiotic space- and Mars-like conditions were performed to analyze the resistance of a range of model organisms. The simulated abiotic space- and Mars-stressors were extreme temperatures, vacuum, and Mars-like surface ultraviolet (UV) irradiation in different atmospheres. We present for the first time simulated space exposure data of mosses using plantlets of the bryophyte genus Grimmia, which is adapted to high altitudinal extreme abiotic conditions at the Swiss Alps. Our preflight tests showed that severe UVR irradiation with the maximal dose of 5 and 6.8 × 10 kJ·m, respectively, was the only stressor with a negative impact on the vitality with a 37% (terrestrial atmosphere) or 36% reduction (space- and Mars-like atmospheres) in photosynthetic activity. With every exposure to UVR 10 kJ·m, the vitality of the bryophytes dropped by 6%. No effect was found, however, by any other stressor. As the mosses were still vital after doses of ultraviolet radiation (UVR) expected during the EXPOSE-R2 mission on ISS, we show that this earliest extant lineage of land plants is highly resistant to extreme abiotic conditions.
作为欧洲航天局“EXPOSE-R2”任务的一部分，该任务在国际空间站（ISS）上进行了 BIOMEX（生物学和火星实验）实验，以研究火星的宜居性和生命的极限。为了准备这项任务，进行了实验验证测试和科学验证测试，模拟了不同的无生命太空和火星条件组合，以分析一系列模式生物的抵抗力。模拟的无生命太空和火星胁迫因素包括极端温度、真空和不同大气中的火星表面紫外线（UV）辐射。我们首次使用适应瑞士阿尔卑斯山高海拔极端无生命条件的藓类植物的原植体展示了使用苔藓植物进行的模拟太空暴露数据。我们的飞行前测试表明，严重的 UVR 辐射（最大剂量分别为 5 和 6.8×10 kJ·m）是唯一对活力有负面影响的胁迫因素，光合作用活性分别降低了 37%（地球大气）或 36%（太空和火星大气）。每暴露于 10 kJ·m 的 UVR，苔藓植物的活力下降 6%。然而，任何其他胁迫因素都没有发现任何影响。由于苔藓植物在国际空间站的 EXPOSE-R2 任务中预计会受到紫外线辐射（UVR）剂量后仍然存活，因此我们表明，这种最早的陆地植物谱系对极端无生命条件具有高度抵抗力。
