Life's Building Blocks Found On Asteroid 24 Themis 135
Hugh Pickens writes "The LA Times reports that scientists analyzing infrared light reflected by 24 Themis, one of the largest asteroids in the solar system, have discovered evidence of water ice as well as organic compounds — findings that bolster a leading theory for the origins of life on Earth that the essential building blocks of life came from asteroids. 'Up until now there was no sign that asteroids had any abundant organics or ice on them,' says Joshua P. Emery, a planetary astronomer at the University of Tennessee. Typically, ice on the surface of an object such as 24 Themis would quickly vaporize and vanish, says planetary scientist Richard Binzel. 'Seeing freshly exposed ice on the surface, now that's a surprise. It has to be replenished from below, somehow.' The possibility that water could have come from asteroids adds weight to the theory that water and organic molecules may not have originated on Earth because the Earth did not become conducive to water or organic molecules until relatively recently."
Re:A Few Skeptical Points (Score:4, Insightful)
Whether or not the asteroids started the evolution of life on earth is hard to tell, but does it really matter?
First of all, "evolution" isn't the issue here, it's biogenesis. Different concepts and it's important to keep them straight. (If only to keep the Creationists from confusing the two more than they already do.)
Second, yes, it matters. If the argument is, "Hey, meteorites have delivered organics, but Earth already had plenty," fine, but
a) That's not what people, especially researchers, keep saying.
b) No one cares if there's no connection to the terrestrial biogenesis. (OK, not no one. It's an interesting datum, but it lacks the cache to get published in the popular press.)
Re:A Few Skeptical Points (Score:3, Insightful)
It's never been clear to me why this mechanism is any better than just forming the danged organics on Earth surface. The Urey-Miller experiments demonstrated nicely that you can form organics under a wide range of conditions.
Yes, I too wonder why people bother to report discovery of simple carbon compound that we know can be easily synthesized in any soup with the good elements.
I always thought the panspermia hypothesis supposed that some basic life forms could cross interplanetary (or even interstellar) gaps thanks to asteroids. It doesn't seem to be the most favored hypothesis for the apparition of life on earth but it could lead to interesting things if it was confirmed. However, the Urey-Miller experiment showed us that amino acids are completely uninteresting substances when it comes to test this hypothesis.
Re:Not testable (Score:3, Insightful)
I was confused by this article for a similar reason. Isn't the earth just a big ol' ball of rock formed by the collisions of a bunch of asteroids that were orbiting in a cloud while the sun was forming? No shit the stuff on earth came from asteroids, the earth was FORMED by asteroids. One way or another, everything on earth has extraterrestrial origins because it had to come from somewhere, and the earth hasn't always existed.
Re:A Few Skeptical Points (Score:3, Insightful)
Better still, do both.
Re:Not testable (Score:2, Insightful)
This is an example of why I've persisted with slashdot for a decade. That's a very interesting analogy!
Re:A Few More Skeptical Points (Score:3, Insightful)
Yes but note that they didn't pick this asteroid at random, they picked it because it was the brightest one known and thus easier to perform the spectral analysis. Ice is highly reflective and probably explains the unusual brightness, it doesn't automatically imply that all asteroids have a similar makeup.
Re:Organic Life Abundant? (Score:3, Insightful)
It would be interesting if life in the Universe was similar enough because planets that bear life are "seeded" in such a way. Frightening, too. That means it's possible that humans might be susceptible to microbes found on other planets.
That statement belies an amazing ignorance about how tightly adapted diseases are to their hosts. You do realize that we're immune to all but the tiny fraction of microbes on Earth which are adapted to live in the ecosystem that is our bodies, right? Why would random space microbes be capable of surviving inside of us?
We can't even get most of the same diseases dogs get, much less germs that survive on frozen, irradiated asteroids.
Re:lots of crashes (Score:3, Insightful)
I'm not a panspermian, but consider what will happen if humanity is currently the only intelligent life in this galaxy or even small area of the galaxy. In a thousand years (if the computers don't exterminate the meatbags and/or have an interest in planets), most planets (in this area) will have received (organic) life from outer space. Personally, I have no desire to colonize other (uninhabited) planets, and would be perfectly happy just to live in solar space (around our sun or another, if it were possible), but I think it will be unlikely that all of humanity will agree with me on that. Even if they agree, they'll at least take a look, and it is notoriously difficult to eradicate bacterial (or archaean) spores in sterilization procedures (our hypothetical non-organic successors may have an easier time, though)...
Consider what would happen if someone seeds moderately Earthlike planets with primitive Earth lifeforms and then leaves it to mature for a billion years. The intelligent life that might evolve could turn into a bunch of unimaginative panspermians, or it could figure out how life could have arisen on its own planets (and did...probably...on Earth).
The TFS implication that (many) people are excited about this from a panspermia perspective is misleading. The thrust of TFA #1 is that it is more difficult for organic compounds to form on an asteroid. The thrust of TFA #2 is that scientists apparently wonder how the Earth came to be covered with water after a catastrophic collision formed the Moon and the surface was superheated. Apparently the water on this asteroid is more similar (in deuterium concentration? TFA is horribly misleading and vague) to the oceans than the water generally found in comets.
I leave you with Christian Science Monitor "science" reporting (not that it's worse than CNN, NYT, PhysOrg, etc.).
But the forms of hydrogen in water molecules bound in asteroids are a closer match to those found in seawater than are those found in water comets carry.