Slashdot Mirror
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.
"findings that bolster a leading theory for the origins of life on Earth that the essential building blocks of life came from asteroids."
No it doesn't, that "leading theory"(*) is untestable and completely ignores contra evidence. Hydrogen, Oxygen and Carbon are respectively the 1st, 3rd and 4th most abundant elements in the universe. Hydrogen and oxygen combust to create water. Modern day volcanos spew all three elements out in large quantities, mainly as water vapour and carbon based molecules. If a rock 100 odd km across has organics and water what in the world make anyone think that a rock over 6000 km in diameter formed from the same primordial material would have have none?
While it's certainly very likely that some water and organics arived via asteroids, frankly the ridiculous improbability that ALL of it arrived via asteroids is too fucking stupid for words. Such psuedo-scientific claptrap only detracts from what is an otherwise fascinating discovery.
(*) = Here is what a real leading theory for abiogenisis looks like; "no ridiculous improbability, no supernatural forces, no lightning striking a puddle, just chemistry", and with a great soundtrack to boot!
And did you exchange a walk on part in the war for a lead role in a cage? - Pink Floyd.
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.
Just because you are paranoid does not mean that no-one is out to get you.
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
Great, now I'm gonna spend all day doing the dimensional analysis to get from X asteriods of water to Y Libraries of Congress. I'll let someone else dig up the relevant xkcd link.
how many asteriods must have crashed into the earth to get all the oceans???
Minimum seven, if each one falls into a different ocean.
It is dangerous to be right when the government is wrong.