The biological risks of the deep space environment must be elucidated to enable a new era of human exploration and scientific discovery beyond low earth orbit (LEO). There is a paucity of deep space biological missions that will inform us of the deleterious biological effects of prolonged exposure to the deep space environment. To safely undertake long-term missions to Mars and space habitation beyond LEO, we must first prove and optimize autonomous biosensors to query the deep space radiation environment. Such biosensors must contain organisms that can survive for extended periods with minimal life support technology and must function reliably with intermittent communication with Earth. NASA's BioSentinel mission, a nanosatellite containing the budding yeast Saccharomyces cerevisiae, is such a biosensor and one of the first biological missions beyond LEO in nearly half a century. It will help fill critical gaps in knowledge about the effects of uniquely composed, chronic, low-flux deep space radiation on biological systems and in particular will provide valuable insight into the DNA damage response to highly ionizing particles. Due to yeast's robustness and desiccation tolerance, it can survive for periods analogous to that of a human Mars mission. In this study, we discuss our optimization of conditions for long-term reagent storage and yeast survival under desiccation in preparation for the BioSentinel mission. We show that long-term yeast cell viability is maximized when cells are air-dried in trehalose solution and stored in a low-relative humidity and low-temperature environment and that dried yeast is sensitive to low doses of deep space-relevant ionizing radiation under these conditions. Our findings will inform the design and development of improved future long-term biological missions into deep space.

中文翻译：

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BioSentinel：用于深空生物传感器任务的长期酿酒酵母保存

必须阐明深空环境的生物风险，以开启人类探索和科学发现超越近地轨道 (LEO) 的新时代。很少有深空生物任务可以让我们了解长期暴露在深空环境中的有害生物效应。要安全地执行长期的火星和低地球轨道以外的空间居住任务，我们必须首先证明和优化自主生物传感器来查询深空辐射环境。这种生物传感器必须包含能够在最少的生命支持技术下存活很长时间的生物体，并且必须能够可靠地与地球进行间歇性通信。NASA 的 BioSentinel 任务，一颗含有发芽酵母的纳米卫星Saccharomyces cerevisiae，就是这样一种生物传感器，也是近半个世纪以来首次超越 LEO 的生物任务之一。它将有助于填补关于独特组成、慢性、低通量深空辐射对生物系统影响的知识空白，特别是将提供对 DNA 对高电离粒子的损伤反应的宝贵见解。由于酵母的稳健性和耐干燥性，它可以存活类似于人类火星任务的时期。在这项研究中，我们讨论了为 BioSentinel 任务做准备的长期试剂储存和酵母在干燥条件下存活的条件优化。我们表明，当细胞在海藻糖溶液中风干并储存在低相对湿度和低温环境中时，酵母细胞的长期生存能力最大化，并且干酵母对低剂量的深空相关电离辐射敏感这些条件。我们的发现将为改进未来深空长期生物任务的设计和开发提供信息。