[LINK] "A Near-Term Read on Life in the Galaxy"

[rfmcdonald]

At Centauri Dreams, Paul Gilster comments on a recent blog post by astrobiologist Caleb Scharf. Assuming that life is actually spread throughout the galaxy by a natural sort of panspermia, what would that life look like? And where would it be found?

Scharf writes:

"Although it’s a complex problem, it seems likely that life driven by cosmic dispersal will end up being completely dominated by the super-hardy, spore-forming, radiation resistant, rock-eating (endolithic) type of critters. There will be no advantage to a particularly diverse gene pool. Billions of years of galactic transferral will have whittled it down to only the most indelicate and non-fussy microbes – super efficient, super persistent, and ubiquitous – the galactic top dogs."

All of this would fit with what we see on Earth, for we know about numerous organisms in extreme environments here that do indeed survive under conditions most living things would consider hostile. Scharf’s point, though, is that if panspermia is true on a galactic level, then tough organisms like these should be just about everywhere. As our robotic probes grow in sophistication, they should start finding life’s tenacious foothold throughout the Solar System, from the ancient seabeds of Mars to the smog-choked surface of Titan. A galactic panspermia would know no favorites, and it has had billions of years to work.

Galactic panspermia, in other words, is going to make itself apparent in the not distant future. If we find that this is not the case, that life doesn’t pop up just about everywhere we look, then the case for panspermia at this level is vastly weakened, although we can still see a role for panspermia between planets. The larger question of life around other stars, in that case, will remain as intractable as it does today, and will require our most advanced instrumentation to detect in the form of atmospheric biomarkers on Earth-like planets near enough to study.