If we were REALLY interested in colonizing space (Mars), we wouldn't be so concerned with contaminants on spacecraft. In fact, we should introduce those microbes (extremophiles) that can withstand the environment of Mars and produce oxygen from carbon dioxide as soon as possible. Evidently, it would appear is as if NASA doesn't want the colonization of Mars. I find this very curiously amusing. It is clear that there is no life there. So we should be purposefully sending blue-green algae (Cyanobacteria) there by the ton.