How Long Can Life Wait?

The work, begun in 2015, indicates that ultraviolet light rather than cold, vacuum or cosmic radiation is the dominant killer of microbes in space, and that a thin dust film, a spacecraft crevice or even layers of dead cells can shield survivors. The findings matter for planetary protection, since probes launched to Mars face short transit times and surface conditions already known to be non-sterilizing, so spacecraft cannot be assumed to self-sterilize in flight. They also bear on how life might have spread through the early Solar System and raise the odds of finding life in asteroids or on Mars if organisms can persist over geological time. Next, watch whether these survival estimates are extended to longer exposures and incorporated into contamination rules for future Mars missions.