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> The researchers suggest that tardigrades would likely not survive an impact with a planet if they traveled across space on an asteroid (as some have suggested
by jiofih 5y ago
> The researchers suggest that tardigrades would likely not survive an impact with a planet if they traveled across space on an asteroid (as some have suggested), as such impacts tend to be at higher speeds
Planets have atmospheres. The terminal velocity for an asteroid on earth will be 100-200 meters per second which is well below that threshold, not sure how they arrived at this conclusion.
- mumblemumble 5y agoI would assume that they're talking about tardigrades traveling from Earth to another planet. The most likely destination from Earth, Mars, would have a much higher terminal velocity.
- tastyfreeze 5y agoNot necessarily. I assumed it was a test to explore the panspermia hypothesis that posits life propagates between planets and stars on ejecta from a planet with life.
- mumblemumble 5y agoI think that it could still be that, but with a focus on panspermia in general, not the specific case of Earth. For the specific case of Earth, wouldn't we want to instead be investigating the survivability of single-celled microbes? It seems like one could rather trivially dismiss the idea that earth was seeded with tardigrade-like organisms based on the fact that they're too evolutionarily advanced to account for six of the seven kingdoms of life we have on this planet.
- ectopod 5y agoIf a tardigrade was sitting on an asteroid, wouldn't the atmosphere blow it free? And then it could float gently down to earth.
- zardo 5y agoI think the real question is could tardigrades (or anything else) survive the ride up from Earth on ejecta.