Figure 1: Experimental Plan of In vivo Animal Exposure.Mouse cohorts (n=5/ group) were fed 0% or 10% FS diet for 3 weeks prior to exposure and remained on test diets throughout the course of the study.Mice were exposed to a double-hit challenge of 0.25 Gy total body ionizing gamma irradiation (IR) and 100% pO2 for 8 hours followed by intermittent normoxia (21% pO2). This cycle was performed 3 times a week for 2 weeks.Mice were sacrificed after 2 weeks of challenge exposure. A total of 24 hours of hyperoxia/radiation exposure weekly simulates the maximum allowed weekly extravehicular activity (EVA) exposure for crewmembers on lengthy spaceflights.