How long can an organism remain inert and still be viable when conditions improve?
The question has big implications in three areas of space exploration. On time scales of years to decades, it dictates our approach to contamination risk when building space probes. On time scales of centuries to millennia, it has implications for how life may have spread around the early Solar System. And if individual organisms can survive for geological time periods—tens to hundreds of millions of years—then this greatly increases the likelihood of our finding life in asteroids and on Mars.
The first place the question of viability comes up is the problem of contamination. Rockets are highly septic structures that sit outside in the Florida sun and launch (from a microbial perspective) absolutely oozing life. When sending spacecraft to potentially habitable worlds, it’s important to know whether we can depend on harsh conditions in space to sterilize them, or have to try to do it ourselves. The question is particularly acute for Mars, where transit times are short, and where we already know conditions on the surface are not lethal enough to eliminate survivors.
