Rethinking planetary protection: an island biogeographical analysis

We reconsider the problem of planetary protection using, by the analogy of planets as islands, the theory of island biogeography. We show that although the notion of equilibrium populations that emerge from the effects of immigration and extinction generally breaks down when applied to interplanetary scales, the mean-time to extinction resulting from the combined effects of growth and death rates can be quantified. We reconsider the probabilistic model of planetary protection, discuss how mean-time to extinction can instead be used to assess contamination risk, and we propose a research direction for planetary protection based on these ideas. We discuss more broadly the applicability of island biogeography to considering biotic transfer at interplanetary scales.