Earth Bacteria May Hitch A Ride To The Stars 221
An anonymous reader writes "Space.com has an article on how old rocket stages are carrying bacteria from Earth to interstellar space. For example, four upper rocket stages were used to boost deep space probes Voyager 1, Voyager 2, Pioneer 10 and New Horizons. The spacecraft were sterilized, but the rocket stages were not, and they now carry the bacteria of the engineers who handled them. If the rocket stages hit a habitable planet, and the bacteria survive the journey, they would be able to reproduce and colonize the planet ... not that there's a high liklihood of that. 'In 40,000 years, this wayward 185-pound (84 kilogram) lump of metal will pass by the star AC+79 3888 at a distance of 1.64 light-years. ... Given the sheer expanse of time that lies ahead of the four discarded rockets, at least one is likely to eventually encounter a planet. But even if that planet's environment is conducive to life, the long dormant bacteria will not just gently plop into some exotic ocean. No soft landing can be expected.'"
Re:Justification? (Score:5, Interesting)
Two thumbs down for cliched half-truths on this article.
-GiH
Not A Worry (Score:5, Interesting)
But even if this is the case what's the big deal. The big reason we want to prevent contamination of mars and similar bodies is for our scientific interest (don't mess up our later experiments). If these organisms colonize some distant planet why is this a bad thing? Now some planet that didn't have any life at all now does. Maybe in a billion years it will evolve spaceships and explore the universe (hell maybe that's how we happened
Either life is common in the universe in which case we just foster a little bit of microbacterial competition (our diseases aren't going to infect complex multicellular aliens) or life is uncommon and we seed a planet with life that might not have otherwise had it. Either way whats the problem?
1.64 light years? (Score:3, Interesting)
Re:Justification? (Score:5, Interesting)
On the other hand, it doesn't take human launched stages to get bacteria from Earth to other planets. In fact, odds are, we've already had bacteria from Earth touch down alive on Titan [planetary.org]. The K-T dinosaur-killing impact alone launched about 600 million rocks from Earth into space. As we now know, Earth rocks tend to be infested with microorganisms, and most rocks that are ejected won't kill the bacteria on the inside (spalling has already been demonstrated to be gentle enough). The sun, Mercury, Venus, Earth, and Mars bear the brunt of the impacts. Mercury and Mars impacts are harsh, due to tenuous atmospheres. Venus impacts are more gentle, but obviously, Venus is a hellish inferno. However, Jupiter can eject fragments further, and that's where things get interesting. About 100 objects strike each Galilean satellite However, with their weak to nonexistent atmospheres, they hit very hard -- 8-40 km/s. You'd be lucky to have even proteins survive. However, Titan has a huge atmosphere, ideal for aerobraking. From this one impact, about 30 Earth meteorites hit Titan within a few million years. They enter the atmosphere at 5-20 km/s, brake, break into fragments, and the fragments hit the surface intact.
Summary:
"That's food for thought -- could Earth have seeded Titan with microbial life? If Gladman's simulations are correct, the material has definitely gotten there in the past. Gladman added, in conclusion, that "if you ever had atmospheres on any of the [presently] airless satellites, they could have acted as aerobrakes" just like Titan's would today."
habitable to bacteria (Score:1, Interesting)
Well, we're talking bacteria here, gravity won't make the slightest difference. It's quite possible that some Earth bacteria could live on a Jupiter-like planet (maybe one that's a bit warmer - as most large extrasolar planets we've found are - and perhaps with different composition). It's also possible that life could evolve on such a planet and be pissed off at meeting Earth bugs.
Still, some other poster got it right. Probability of going close to a star and getting melted >> probability of hitting a planet.
Re:Justification? (Score:3, Interesting)
The problem I see with GP is that I don't think a multibody system would change the outcome of case (a). If the traveling object encounters a system of, say, 5 stars, and has an initially hyperbolic trajectory about their common center of mass, then when it approaches Star #1, that star will have more influence than the other 4, changing the direction but not reducing the total energy of the traveling object. With the same total energy (and assuming no collision), the approaching body would still be able to escape, no matter how many close approaches it makes to the bodies in the system. I don't think capture can occur unless the gases near the stars provide enough braking to reduce this total energy. But that could also happen with a single star.