How do you sufficiently sterilize wood to protect mars from contamination? I imagine this is less trivial than sterilizing metal, plastic, whatever other materials typically go into space-vehicle production.
I was thinking the same thing, and then I also thought - if the long term plans are colonization, is sterilization and non-contamination viable, or even desirable?
While the missions remain scientific I absolutely agree contamination must be avoided. But as soon as we cross into the colony phase, wouldn’t that restriction just make things harder?
If we’re into the colonization phase in the future we’ll be intentionally contaminating the planet trying to grow crops, so yes we’d be past that as a point of consideration.
> But as soon as we cross into the colony phase, wouldn’t that restriction just make things harder?
I think not just harder, because the first colonies will enable scientists to study the pristine environment in more depth, while the colonies itself will be small and costs of a sterilization will be relatively low. So the onset of uncontrolled contamination should probably be delayed until well after the first colony.
In addition to vacuum exposure to address outgassing, they'd probably hit wood with some sterilization process (gamma radiation as one example) to ensure any microbes in the wood are dead before landing on another planet.
I assume that a combination of high temperature and irradiation should be effective.
Wood should not be damaged by temperatures high enough to kill living cells and it provides negligible shielding for radiation.
However, after sterilization it may require more care than metal, glass or plastic, to avoid any later contamination. Presumably all the assembly must be done in a sterile environment.
Unlike metal or glass, which could be washed in oxidizing acids to remove organic substances, sterilized wood may contain dead bacterial cells in its pores. For satellites expected to burn on reentry that would not matter. For exploring other planets, that would be undesirable, as this could provide false positives for detectors of organic substances.
> Wood should not be damaged by temperatures high enough to kill living cells
Yep, in NASA's planetary protection guidelines they have bakeout timelines specified for microbial reduction at temperatures between 112C and 155C. There are a number of other cleaning and sterilization methods in there as well.
