Earth’s atmosphere and magnetosphere deflect and absorb the majority of harmful radiation traversing Space; however, once outside Low Earth Orbit (LEO), payloads are exposed to Galactic Cosmic Rays (GCR) and Solar Particle Events (SPEs). While humans possess capabilities that hardware does not, we are uniquely vulnerable to radiation. Detrimental effects range from nausea and dizziness brought by intense, short term doses to increased cancer risk and impaired cognitive function associated with chronic exposure. This paper aims to explore the use of human waste (feces and urine) as radiation shields in a comparative study of urine v. water and hydrated v. dehydrated feces. GCR contain particles with orders of magnitude higher energy than SPEs, which makes them impractical to shield against. Conversely, SPE occur with higher frequency and at a lower level that is practically attenuated. To this end, an SPE surrogate was validated and exposure (Counts) on the leeward side of the respective shields was measured. Counts per Minute (CPM) were obtained by applying a multiplicative factor to Counts. As expected, CPM behind a urine shield did not differ from CPM behind a water shield (t-test, p < 0.05). Similarly, no difference in leeward CPM was found between hydrated and dehydrated feces shields (t-test, p < 0.05). The lack of differences between water and urine may be a result of urine being composed primarily of water. While fecal matter is made primarily of water as well, the solid content likely masks the loss of water’s attenuation properties.
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Falck, Noah L.
"Radiation Exposure During Space Travel: Using Radioisotopes for a Comparative Study of Human Feces and Urine as Integrated Shield Components,"
1, Article 4.
Available at: http://digitalcommons.calpoly.edu/symposium/vol4/iss1/4