Unusual Micrometeorite Found in Antarctica
Written by Nancy Atkinson
Micrometeorite. Credit: Washington State University
A miniature meteorite unlike any other has been discovered in Antarctica. The tiny rock, known as MM40, is the first achondritic basaltic micrometeorite ever found on Earth. Detailed analysis shows it has an unusual chemical composition the researchers say raises questions about where it originated in the Solar System and how it was created. "We have basaltic meteorites that are thought to come from an asteroid called 4 Vesta and we also have basaltic meteorites from the Moon and Mars," said Dr. Caroline Smith, curator of meteorites at the Natural History Museum, London "But MM04's chemistry does not match any of those places. It has to be from somewhere else."
MM40 is only 150 microns across as its widest point, (.0059055 inches) or about as big as the period at the end of this sentence.
Chondritic meteorites were formed during the the Solar System's early days before material had accreted into planets. They have not been altered by the melting and re-crystalisation that takes place during planetary formation and erosional forces similar to what Earth rocks undergo.
Achondritic meteorites, by contrast, were formed when the Solar System's planets were coming into being. The substances in such meteorites and the processes they have undergone can give clues about how the larger bodies were formed.
The research team, led by Matthieu Gounelle from the Laboratory of Mineralogy and Cosmochemistry at the French Natural History Museum, says the discovery of this new type of basaltic meteorite expands the solar system inventory of planetary crusts. "The parent asteroid of MM40 has undergone extensive metamorphism," the researchers write, "which ended no earlier than 7.9 million years after solar system formation. Numerical simulations of dust transport dynamics suggest that MM40 might originate from one of the recently discovered basaltic asteroids that are not members of the Vesta family."
While its ultimate origins are a mystery it does have implications for the ways that astrochemists thought planets could be formed. The analysis of MM04 showed that the "inventory" of such processes must be expanded, said Dr. Smith.
"Micrometeorites are often seen as the 'poor man's space probe'," she said. "They land on Earth fortuitously and we do not have to spend millions of dollars or euros on a robotic mission to get them."
Sources: Proceedings from the National Academy of Sciences, BBC
Filed under: Meteorites
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April 9th, 2009 at 2:21 pm
I wonder how the uniformitarians are going to try and explain this one.
"During the years I visited with Fred [Hoyle] from time to time to show him the newest observational results which were struggling to get published. He would instantly size up the results and say something like, 'Well chip, they will certainly have to admit now that their assumptions are wrong.' After a while we both knew that it would not be accepted in the foreseeable future. He never dwelt on the lost effort, money or the dismal state of the science. He was always trying to think ahead to the next insight, the next synthesis of physics. It will always be a pleasure and inspiration however to look back and read his clear, courageous logic and also sad to think how far ahead we might be now if more people had joined in the discovery of new understandings instead of insisting on complexifying and patching up their commitment to old dogma. I can still hear him saying, 'They defend the old theories by complicating things to the point of incomprehensibility.' We should have crossed over that bridge to a more correct physics that Fred pointed to so clearly more than three decades ago." — Halton C. Arp, astronomer, 2003
April 9th, 2009 at 3:23 pm
Ignorant, pigheaded comment: check. Irrelevant quote: check.
April 9th, 2009 at 3:35 pm
Please some one tell me- How do you find a meteorite the size of the period at the end of this sentence. And when you do- how do you know that it is the rock that you wish to study?
The article says that it is "the first achondritic basaltic micrometeorite ever found on Earth." Does this mean that we found these on the moon?
And does one little rock really prove anything? I suppose if we found a hundred or a thousand of them and the tests gave the similar results that it might be statistically valid- but just one tiny rock with no other examples…..
Sorry lots of questions!
April 9th, 2009 at 3:57 pm
"Please some one tell me- How do you find a meteorite the size of the period at the end of this sentence. "
My thoughts exactly. How do we really know this didn't come out of the arse of the mythical Antarctic mosquito. ;o)
April 9th, 2009 at 4:51 pm
Oils: How do YOU care to explain this one?
April 9th, 2009 at 5:22 pm
I with Layman on this one, a lot more information on this story is needed to fill in some gaps.
April 9th, 2009 at 5:26 pm
Who has a (free) link to this paper?
April 9th, 2009 at 5:41 pm
After thinking about this for a while I remember that I have read that scientists search the barren ice covered areas of Antarctica for meteorites because a stone on top of the ice sticks out like a sore thumb.
I am going to guess that they had to use a magnet to find this rock and perhaps when it was placed it under a microscope they noticed that it was very unusual.
Still I want to know more!
April 9th, 2009 at 6:30 pm
@Jon Hanford
I googled "achondritic basaltic micrometeorite" The paper can be found on the 2nd site listed
April 9th, 2009 at 9:37 pm
Oils, you might find this paper by Alfven to be quite interesting. The 96 pages are worth the read.
http://articles.adsabs.harvard.edu//full/1974Ap%26SS..29…63A/0000063.000.html
"While its ultimate origins are a mystery it does have implications for the ways that astrochemists thought planets could be formed. The analysis of MM04 showed that the “inventory” of such processes must be expanded, said Dr. Smith."
Why re-invent the wheel? The above paper is already in the "inventory". And by a Nobel Prize winning physicist at that.
Regardless;
How do we even know this is from our solar system? Aren't we moving through an interstellar 'dust' cloud about now, and doesn't this happen with some sort of relative frequency? If they found this in Antarctica recently, it must have been on, or near, the surface. Maybe this tells us something about the galaxy, or interstellar space, rather than our own backyard.
April 9th, 2009 at 11:29 pm
Oils: How do YOU care to explain this one?
That's what I was wondering. I got halfway through his rant before I realized he was not even going to try and relate his post in any way to this article's topic.
April 10th, 2009 at 1:06 am
Oh, I dunno, Oils' post was kind of interesting regarding how uniformitarians (geologic steady-staters) might fold the data from this bemusing little meteorite into their theory. And then the clip which illustrated how Hoyle (who could arguably have fit the definition of uniformitarian) would have used his "clear" logic to refute complications imposed on our understanding of geologic processes by data from this bit of achondritic basalt.
So, Oils, points for an interesting thing to think about, but negative points for lack of narrative.
April 10th, 2009 at 1:58 am
Notes for the users of British English the word "period" refers to what we call a "full stop"
4 Vesta comes from the fact that Vesta was the 4th "asteroid " to be discovered – by Olbers in 1807.
See Nancy's previous article re aerosols in the Arctic.
Mind you getting a 150 micron particle found and isolated is quiet a feat.
April 10th, 2009 at 7:08 am
"The size of a period." Really!!!
April 10th, 2009 at 9:02 am
I just finished some work on martian basaltic meteorites recently, and this stuff is very interesting, I read this paper during the week.
Finding bits of rock on ice fields in Antarctica is easy, and the only rocks on the ice are going to be meteorites.
What to study is the hard part, but your more likely to sample for constituents in a rock grain this size as visual studies would be not very informative.
This is a good example of why looking for meteorites is not only fun but if your lucky enough its the same as doing a sample return mission from a planetary body.
April 10th, 2009 at 12:15 pm
I was wondering what the composition of it was? On an aside, this blog space would be a whole lot shorter if the Gadflies got no responses. It, of course, is very fun to play that role if everyone takes the bait and 3/4 of the messages relate to your banter. MOK
April 10th, 2009 at 2:59 pm
Hey Layman, Thanks for the the advice that led to the paper. For others interested in this 2 page 'letter' see: http://www.lpi.usra.edu/meetings/lpsc2005/pdf/1655.pdf . It's short but sweet. Amazing what polite, on topic posts can do do for the truly curious. @mike, check out the paper about the micrometeorite, above, for details about its composition.
April 11th, 2009 at 9:34 am
@ Spoodle58 "Finding bits of rock on ice fields in Antarctica is easy, and the only rocks on the ice are going to be meteorites." Again, ref. Nancy's article on atmospheric particulates…
Stirred up stuff from your back yard can end up in my back yard.
@Mike "I was wondering what the composition of it was?" I wonder this as well. Could this just be a synthesized contaminant that originated in a North Korean lab?
Also, the "micro ?" could have been discovered while analyzing one of ice core samples and not necessarily on the surface (current era). It wasn't stated where/how it was obtained. Or did I miss that?
April 11th, 2009 at 12:03 pm
Erm… Guys? Please. It's the same on every news site.
Is the achondrite called MM04 or MM40?
(!)
April 11th, 2009 at 2:24 pm
@ Invader Xan, the achondrite micrometeorite is known as MM40. My previous post contains a link to a paper about MM40, including its' composition. The researchers find the sample contains "plagioclase, high calcium pyroxene, silica, minor oxides and iron sulfides". I refer you to the paper mentioned above for a more complete analysis of the sample and the abundances of its' constituents.
April 13th, 2009 at 7:07 am
Jon,
Thank you very much. I'd been meaning on searching for the actual paper. (Actually, that's why I wanted to know the meteorite's correct name).
April 13th, 2009 at 12:07 pm
@Invader Xan, Thanks for your reply. But I give credit where credit is due so I again thank Layman's April 9th 6:30 pm post above: " I googled “achondritic basaltic micrometeorite” The paper can be found on the 2nd site listed". Just passing on good info, so I hope it's helpful.