Viúdez-Moreiras Daniel, Zorzano Maria-Paz, Lemmon Mark T, Fairén Alberto G, Saiz-Lopez Alfonso, Smith Michael D
Centro de Astrobiología, Spanish National Research Council - National Institute for Aerospace Technology, Torrejón de Ardoz, Madrid 28850, Spain.
Space Science Institute, Boulder, CO 80301.
Proc Natl Acad Sci U S A. 2025 May 27;122(21):e2426611122. doi: 10.1073/pnas.2426611122. Epub 2025 May 12.
The incident ultraviolet (UV) irradiance on the surface of Mars is strongly sterilizing and plays a critical role in atmospheric and near-surface photochemistry. The Rover Environmental Monitoring Station (REMS) instrument, which includes the first UV sensor sent to Mars on board the Curiosity rover, has been measuring the UV irradiance at Gale Crater since 2012, providing ground-truth data regarding seasonal and short-term variability of the UV radiation at the surface of another planet. Here, we analyze the REMS UV measurements for a period of >5 Martian years to retrieve biological effective doses and other UV radiation quantities on the planetary surface that are key for different physicochemical processes. Our results reveal a previously unidentified complex UV radiation environment on the Martian surface, with dramatic short-term fluctuations capable of changing UV radiation doses by >30% in a few sols. We assess the viability of terrestrial microorganisms exposed to this UV radiation field and dispersed through the Martian atmosphere from a robotic spacecraft or human habitat. Our findings show that reducing microbial viability by 99% would require several hours of exposure to the Martian environment including during the daytime, a finding that may call for a reinforcement of planetary protection policies.
火星表面的入射紫外线（UV）辐照度具有很强的杀菌作用，并且在大气和近地表光化学过程中起着关键作用。火星车环境监测站（REMS）仪器包括好奇号火星车上搭载的首个紫外线传感器，自2012年以来一直在测量盖尔陨石坑的紫外线辐照度，提供了有关另一颗行星表面紫外线辐射季节性和短期变化的实测数据。在这里，我们分析了超过5个火星年的REMS紫外线测量数据，以获取对不同物理化学过程至关重要的行星表面生物有效剂量和其他紫外线辐射量。我们的结果揭示了火星表面以前未被识别的复杂紫外线辐射环境，其具有剧烈的短期波动，能够在几个火星日中将紫外线辐射剂量改变超过30%。我们评估了暴露于这种紫外线辐射场并通过机器人航天器或人类栖息地散布在火星大气中的陆地微生物的生存能力。我们的研究结果表明，将微生物生存能力降低99%需要在包括白天在内的火星环境中暴露几个小时，这一发现可能需要加强行星保护政策。
