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."
A Few Skeptical Points (Score:5, Interesting)
If their argument is that early Earth wasn't conducive to water, it's not clear how bringing in organics and water would help. If you bring in organics to a hot planet, they'll break apart just as surely as if they had formed there, after all.
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. (Which ones correspond to early Earth is an outstanding question, but it doesn't appear to much matter, oddly.)
Come to all that, we don't know that these asteroids (assuming they are asteroids and not dead comets, which it kind of sounds like they may be...) had much in the way of organics 4 billion years ago or if the organics formed due to reactions since then.
Basically, I'm uncomfortable with how excited people seem to get about the idea that this might have delivered the "building blocks of life" to Earth. Possible, sure, but it's far from a strong case.
Re:A Few Skeptical Points (Score:2, Interesting)
Actually it's almost inevitable that organic compounds made it to earth via asteroids at some point. Organic compounds are really common on other planets and moons even in our solar system.
Whether or not the asteroids started the evolution of life on earth is hard to tell, but does it really matter? This is just one more way to explain why earth billions of years of ago sparked life.
Their theory is plausible at the least.
A Few More Skeptical Points (Score:2, Interesting)
I'm glad that two teams independently verified it but I'm a little concerned that there may be a flaw in the methodology of the reflection of the light. I'm sure they've accounted for everything but I'm just concerned because the only logical explanation is either our fundamental understandings of asteroids is largely incomplete (the first one they picked was laden with organic molecules where normally there are but a few traces) or the methodology of determining their composition falls prey to some unforeseen phenomenon/distortion in this case.
I'm sure I'm not the only one excited to see what the Japanese bring back from the Itokawa Asteroid [slashdot.org].
Re:A Few More Skeptical Points (Score:5, Interesting)
The water on the surface of 24 Themis does not have to come from within the asteroid, it can be created through surface chemistry between the solar wind and the surface of the asteroid. The process is similar what has been proposed to explain some of the water layer found on the surface of the Moon. In essence, the water on the asteroid is being continually created. Water that is lost is replaced through chemical reactions over time.
Free propellant! (Score:5, Interesting)
Re:A Few Skeptical Points (Score:2, Interesting)
The thing I don't get is how "finding signs of water" and the "basic building blocks of life" on asteroids/other planetary elements is such a huge deal. Logic indicates with hundreds of billions of planets in the universe that water or other "basic building blocks of life" would be present on at least some other elements in the universe.
Re:Not testable (Score:3, Interesting)
Very impressive video and I tend to agree: It seems probable to me that the basic life-giving elements could have been delivered via abiogenisis AND space, since it's all basically made up of the same stuff. Just like the early organisms being bounced around in the oceans and picking up new parts, why couldn't the universe be considered just one huge ocean where all the rocks (whether planets or asteroids) have the same parts and the big ones borrow from the small ones?
Very cool
Re:A Few Skeptical Points (Score:3, Interesting)
"Space-organics are just as fragile to heat as terrestrial-made versions."
that's actually unknown. They could be more adaptable to space, but the properties for that environment where no longer required after being on earth. So they weren't need to evolve.
I don't care where it started, but if w did get her vie space seeds, then not only does it increase the likelihood of life elsewhere.
If ti turns out the the properties of space organics is as fragile as you speculated, that means other life out there may be similar to here on earth.