Water, Water Everywhere... and Oxidants too!

The current predominant scientific strategy to find evidence for the existence of extraterrestrial life has been to "follow the water". Life on Earth requires the availability of water, so it makes sense that this is a good place to start when trying to evidence of extant or extinct signatures of life beyond our planet. However, life on Earth also requires redox gradients. Respiration and photosynthesis are two such examples of redox chemistry that is essential for life. Planetary surfaces and atmospheres are naturally oxidized by photolytic and radiolytic processes. Even on early Earth and Titan, the natural oxidation of primordial ammonia presumably created the present nitrogen atmospheres, respectively as real and potential abodes for life. In the cases of Mars, Europa and Enceladus, three bodies of intense astrobiological interest, the natural oxidation processes driven by space environment interactions can produce significant quantities of oxidants, which could potentially be utilized to sustain life. We propose, that in addition to the "follow the water" strategy, the scientific community should start to "follow the oxidants", as a potentially important avenue of research and exploration. We address models for oxidant formation in planetary surface irradiation environments, as simulated by laboratory investigations, and apply results to past, recent and ongoing planetary observations of Mars and icy bodies of potential astrobiological interest in the outer solar system.