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Life's Building Blocks Found On Asteroid 24 Themis
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."
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.
I am not an astronomer but there also seems to be a lot of improbable things in this story. Obviously it's odd to find ice and organics on an asteroid but not impossible. But it's the first asteroid (24 Themis) these two teams have independently looked at. It's evenly distributed on the surface as well which is also odd. And it has to be replenished from within -- which I think challenges a lot of assumptions about asteroids -- otherwise this water would have baked away a long time ago. These last two might be related in that the asteroid has a water table with seepage from the inside out that -- due to a lack of strong gravity or possibly the Yarkovsky effect -- is distributed fairly evenly.
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.
My work here is dung.
Life, Shmife! We are not focusing on the most important aspect of this report. The key is that there is sizable amounts water available in (relatively) nearby orbits outside of any significant gravity well. If the water can be used to refuel ships on their way to outer orbits, this could be incredibly useful for deep space exploration. I would personally prefer to see a space station on 24 Themis than on the moon, and it is less work to get there. Ok, more time but less work.
"I love his boyish charm, but I hate his childishness" - Leela
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
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