| Summary: | As aeronautic technology advances, so does the possibility of long‐term space travel and exploration. However, in order to make significant strides, it is first necessary to determine how to survive the antagonistic space environment, including temperature extremes, UVC radiation, and vacuum pressures, among others. Tardigrades are microscopic invertebrates that possess the ability to adapt to extreme environments through the formation of a tun, a dormant structure resulting from the downregulation of metabolism. This ability to survive under extreme conditions, including arctic temperatures, extreme heat, and a pure vacuum, makes tardigrades a useful model organism for space survival. By increasing our understanding of their survival mechanisms on a fundamental level, we may be able to generate technologies that protect humans in space from diseases caused by ROS and the damaging effects of oxidative stress. Previous research has examined the physiological response of tardigrades subjected to freezes and irradiation that model outer Earth conditions. In these studies, tardigrades were shown to enter tun formation through cryptobiosis, especially in response to physical stressors causing desiccation. Another study assessed tardigrades’ intergalactic survival capability by sending a culture into the vacuum of space, after which the cultures showed no loss of viability. We hypothesize that tardigrades have a specific, protective mechanism to respond to oxidative stress through the increased expression of superoxide dismutases (SODs) to break down potentially harmful ROS, which is supported by previous studies showing both the formation of superoxide radicals as well as an increase in SODs in desiccated animals. In this study, X‐band continuous wave electron paramagnetic resonance (EPR) spectroscopy was used to measure the presence of superoxide radicals in the tardigrade Hypsibius exemplaris before and after exposure to environmental stressors. Tardigrades were subjected to a combination of UVA and UVB irradiation ...
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