CHIP OFF THE OLD BLOCK: In an artist's conception, 24 Themis is depicted alongside two smaller members of its dynamical family, the members of which likely originated from the same parent body. The lower fragment, a so-called main-belt comet, has a tail but orbits within the asteroid belt.
Image: Gabriel Perez, Servicio MultiMedia, Instituto de Astrofisica de Canarias, Tenerife, Spain)
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An asteroid circling the sun between the orbits of Mars and Jupiter has for the first time been shown to harbor water ice and organic compounds. Those traits had been associated with comets, which spring from colder, more distant reservoirs in the outer solar system, but not their asteroidal cousins. The finding supports the notion that asteroids could have provided early Earth with water for its oceans as well as some of the prebiotic compounds that allowed life to develop.
Two teams of researchers report complementary observations of the 200-kilometer-wide asteroid, known as 24 Themis, in the April 29 issue of Nature. (Scientific American is part of Nature Publishing Group.) Both analyses are based on spectroscopic observations from the NASA Infrared Telescope Facility atop Mauna Kea in Hawaii, which show absorption features that indicate the presence of water and unidentified organic compounds. The ice appears to coat the entire asteroid as a thin layer of frost. The evidence for water on 24 Themis had been presented at conferences by the two groups in 2008 and 2009 but is only now appearing in a peer-reviewed journal.
"They have found something that a lot of people, including myself, have been chasing in the solar system for a long time, and that is water and organic material," says Dale Cruikshank, a planetary scientist at the NASA Ames Research Center in Moffett Field, Calif.
The asteroid was a promising target in part because it shares a similar orbit with a few so-called main-belt comets, which are objects in the asteroid belt that feature comet-like tails thought to be provided by the sublimation of ice to water vapor. Because 24 Themis likely came from the same parent body, it seemed plausible that it could harbor ice as well.
Cruikshank notes that some meteorites bear the signature of water and organic compounds, and that researchers have long been looking for the source of those meteorites. Now it appears that 24 Themis could fit the bill. "These newly discovered [main-belt comets], and now Themis, are very interesting objects and potentially one of the sources of Earth's oceans."
The two studies give a fairly comprehensive view of the asteroid; one sampled 24 Themis at various points through its orbit, in brief intervals spanning several years, whereas the other followed the asteroid for several hours in one sitting to spot any changes as the body rotated on its axis.
"I thought, 'There has to be something in that family that is making these small objects behave like comets'," says Humberto Campins, an astronomy professor at the University of Central Florida who co-authored the study that was based on a seven-hour observation of 24 Themis in 2008. There was indirect evidence to suggest that some asteroids had not been baked dry by the sun, Campins says, but no proof.
The authors of the other study observed the asteroid seven times between 2002 and 2008 before they were convinced. "At first, we didn't necessarily believe it," says Andrew Rivkin, a planetary astronomer at the Johns Hopkins University Applied Physics Laboratory who collaborated with Joshua Emery, a planetary scientist at the University of Tennessee, Knoxville. "It took a few tries, including one of those years where we were able to see it on back-to-back nights, before we could say, 'Now we really do believe this is for real'." The stability of ice on an airless body in space, Rivkin explains, is very sensitive to temperature, and 24 Themis appeared to be right on the cusp of plausibility. "If it were a few degrees warmer, you'd say no way," he says.
As astronomers look farther out in the solar system with constantly improving telescopes and instrumentation, Campins says, they may find ice on more asteroids. "We may need to look more carefully," he adds. "Or it could be unique to Themis. We don't know."
Cruikshank says it is somewhat surprising to find water ice on an airless body so close to the sun, but he notes that such revelations are becoming the norm—just look at the recent demonstrations of widespread water ice on the moon. "We're quite accustomed to being surprised," he says.
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14 Comments
Add CommentMy question is - how did the prebiotic, organic compounds form in open space? How do they and a layer of frost get deposited on an asteroid in the first place?
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Reply | Report Abuse | Link to thisThis discovery is remarkable !
I believe that we will able to change the orbit of this and others ice-asteroid using rocket boosters to put them into the Mars Orbit for collision route filling the planet with water...(maybe a small sea).
This could be the first step in a long way to prepare the Mars' environment for a massive human colonization of that planet.
@rougarou: What the f***? Are you just kidding, or are you making fun of the nutcases who believe similarly crazy stuff (Poe's Law)?
Reply | Report Abuse | Link to this@fndtomas: I've had a similar idea for a while, but really we don't need such a large asteroid, Mars has enough water ice to cover the planet in a very shallow sea, all we would need is an impact on one of the poles to melt it and redistribute it. Fill the atmosphere with GHGs to heat it up, and find a way to hold down the atmosphere, and add O2 to the atmosphere, and we're set.
Ah yes...another important reason to establish a base on the moon effectively shot down, and yet another great reason to make the asteroids and their ever more evident bounty the best choice for a deeper space station from which to explore the solar neighborhood. Now that we know we can get water, which aside from its essential role in life makes a superb propellant that otherwise,under the current misbegotten launch system which was orginally created as a ICBM launch system, still ends up costing $20K per pound just to get it up there. The availability of propellant combined with asteroids' almost non-existent gravity fields makes it an excellent place from which to explore and to exploit. Cheers.
Reply | Report Abuse | Link to thisThis is not a random or aberrant occurrance. There is a great deal of debate about whether evolution is real or some god created life on Earth. The truth is that life is not indigenous to Earth at all.
Reply | Report Abuse | Link to thisDeep within the core of our galaxy is a 'super planet' which is known to be the cradle of all life within our corner of the universe. It routinely spawns these asteroids implanted with organic precursors to complex lifeforms and hurls them out into the cosmos, as seeds for new living worlds.
We are nothing more than a snapshot of the amazing biodiversity of the first true ecosystem on that core planet. Our purpose is to survive and grow so that its memory may not be forgotten.
fndtomas, fisixisfun - The solution to all our problems is not to abandon the only known planet perfectly capable of supporting complex life after we've consumed all its resources, moving on to the next victim like a virus. The New World was America - there aren't any more like it! If we can't learn to live here with all we still have, why on Earth would you think we could survive anywhere else??
Reply | Report Abuse | Link to thisGet a grip on reality and learn to live within our means, or prepare to abandon humanity to untold suffering. Anyway 'we' might move on to a better place, most of 'us' 9+ billion people would suffer endlessly. Is that your choice?
I glad having someone with similar ideas ;-) ...
Reply | Report Abuse | Link to thisTrying to complement ...
I think that the asteroid belt is a kind of "Resource Poll".
After mapping the chemical composition of the asteroids We could perfectly select the best combination of ingredients
(and asteroids sizes) to fill the Mars environment with the similar composition found on Earth.
I strongly believe that it is possible using real and "low cost" asteroid orbit redefinition system in a "short" time scale.
I believe that this kind of studies are remarkable because we have now the opportunity to do
with Mars what happened on Earth during billions of years but now using a human controlled proccess!
It is a real possibility !
Tomas Fernandes, Brazil.
Sorry @jtdwyer, but I think that you are talking about different things...
Reply | Report Abuse | Link to thisIt is not the same question...
I really agree with almost all you said. We need to take care of our current planet,
but it doesn't mean that we can't prepare the next planet for colonization at least
to give us the chance to survive if a catastrophic event occurs naturally on Earth.
I don't believe that it is a virus behavior...
Tomas
Considering Earth IS a conglomerate of trillions of asteroids, isnt it redundant to say that asteroids brought water to Earth? As if, the planet was formed, was sitting there, dry as a bone, and then luckily, all these water-bearing asteroids crashed down after the fact, and brought the water. Earth has so much water because after the proto-Earth collided with the other celestial body that caused it to completely melt, forming the moon, and thereby allowing all the elements to re-mix with all the heavier elements sinking to the core, and the lighter elements like water were able to rise to the surface, not in liquid form until it cooled enough of course, but nonetheless the Earth's water can be attributed to the fact of this titanic collision allowing for the distribution of the elements in a more organized fashion, unlike other planets that didnt have the benefit of being totally re-melted due to the collision of the two proto-planets that gave us the full sized Earth, plus our Moon. Anyway my point is, the Earth had all the water it needed to begin with, but due to the collision that formed the moon, the elements had the opportunity to re-distribute in a fashion that allowed the water to settle on the surface. So the idea of the Earth being bone-dry and lucking out with all these wet asteroids is a weak-minded, boring, mundane, cowardly idea, typical of how science approaches the obvious displayed by nature. Nature is always far more exotic and dynamic and interesting than science is ready to accept, at any point in history. Not long ago the idea of water on any other celestial body way controversial. Science needs to quit being so skeptical and open its eyes to the obvious grandeur of nature, instead of cowering in the boring and safe and mundane.
Reply | Report Abuse | Link to thisI thought that water ice on the moon was a result of nuclear interactions with cosmic rays.
Reply | Report Abuse | Link to thisI think maybe you need to retake reading & comprehension.
Reply | Report Abuse | Link to thisDisregard, point that comment at me.
Reply | Report Abuse | Link to thisfinding liquid water organics on an asteroid next to mars, instead of just in a comet, indicates to me that we from earth cannot contaminate Mars by a simple small sized space flight landing. It's no different then what has already been going on for billions of years in our solar system, where organics have to have a firm enough footing on an asteroid or planet to form living matter.
Reply | Report Abuse | Link to thisAbout 5 to 6 billion years ago maybe more there was a stellar nursery in which a number of stars went supernova and it was from these that the water and all organic materials came from as well as all the elements now found in our solar system.Then our own star began,forming a disk about it acting like giant mixer forming all the planets,asteroid and comets.Of course some were left over from the 1st stars.Then sometime in the next billion years life began here on Earth,it didn't have to come from somewhere else.It stared somewhere ,and this place is as good as any.How it happened may never be known,unless we build a time machine and go back for a look.I think it happened from the almost endless tidal waves sweeping driven by the new Moon.This created an untold number of bubbles,and with each bubble formed a new grouping of elements and minerals formed inside till finally one had all the right things in all the right places,and there it was life,and it replicated and so on and so form.Of course it could have went different with life not forming here,but on some of the other billions of planets in the universe.And the story keeps going on with us trying to figure how and why.We are in the end nothing more than the universe looking at itself.Isn't wonderful.
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