The anatomy of an asteroid

Feb 05, 2014
This is a schematic view of the strange peanut-shaped asteroid Itokawa. By making exquisitely precise timing measurements using ESO's New Technology Telescope, and combining them with a model of the asteroid's surface topography, a team of astronomers has found that different parts of this asteroid have different densities. As well as revealing secrets about the asteroid's formation, finding out what lies below the surface of asteroids may also shed light on what happens when bodies collide in the Solar System, and provide clues about how planets form. The shape model used for this view is based on the images collected by JAXA's Hayabusa spacecraft. Credit: ESO. Acknowledgement: JAXA

ESO's New Technology Telescope has been used to find the first evidence that asteroids can have a highly varied internal structure. By making measurements astronomers have found that different parts of the asteroid Itokawa have different densities. As well as revealing secrets about the asteroid's formation, finding out what lies below the surface may also shed light on what happens when bodies collide in the Solar System, and provide clues about how planets form.

Using very precise ground-based observations, Stephen Lowry (University of Kent, UK) and colleagues have measured the speed at which the near-Earth (25143) Itokawa spins and how that spin rate is changing over time. They have combined these delicate observations with new theoretical work on how asteroids radiate heat.

This small asteroid is an intriguing subject as it has a strange peanut shape, as revealed by the Japanese spacecraft Hayabusa in 2005. To probe its , Lowry's team used images gathered from 2001 to 2013, by ESO's New Technology Telescope (NTT) at the La Silla Observatory in Chile among others, to measure its brightness variation as it rotates. This timing data was then used to deduce the asteroid's spin period very accurately and determine how it is changing over time. When combined with knowledge of the asteroid's shape this allowed them to explore its interior—revealing the complexity within its core for the first time.

"This is the first time we have ever been able to to determine what it is like inside an asteroid," explains Lowry. "We can see that Itokawa has a highly varied structure—this finding is a significant step forward in our understanding of rocky bodies in the Solar System."

The spin of an asteroid and other small bodies in space can be affected by sunlight. This phenomenon, known as the Yarkovsky-O'Keefe-Radzievskii-Paddack (YORP) effect, occurs when absorbed light from the Sun is re-emitted from the surface of the object in the form of heat. When the shape of the asteroid is very irregular the heat is not radiated evenly and this creates a tiny, but continuous, torque on the body and changes its spin rate.

Lowry's team measured that the YORP effect was slowly accelerating the rate at which Itokawa spins. The change in rotation period is tiny—a mere 0.045 seconds per year. But this was very different from what was expected and can only be explained if the two parts of the asteroid's peanut shape have different densities.

This is the first time that astronomers have found evidence for the highly varied internal structure of asteroids. Up until now, the properties of asteroid interiors could only be inferred using rough overall density measurements. This rare glimpse into the diverse innards of Itokawa has led to much speculation regarding its formation. One possibility is that it formed from the two components of a double asteroid after they bumped together and merged.

Lowry added, "Finding that asteroids don't have homogeneous interiors has far-reaching implications, particularly for models of binary asteroid formation. It could also help with work on reducing the danger of asteroid collisions with Earth, or with plans for future trips to these rocky bodies."

This new ability to probe the interior of an asteroid is a significant step forward, and may help to unlock many secrets of these mysterious objects.

Explore further: Space shuttle-sized asteroid 2013 XY8 to fly past earth on Dec. 11

More information: This research was presented in a paper "The Internal Structure of Asteroid (25143) Itokawa as Revealed by Detection of YORP Spin-up", by Lowry et al., to appear in the journal Astronomy & Astrophysics.

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GSwift7
5 / 5 (3) Feb 05, 2014
Finding that asteroids don't have homogeneous interiors has far-reaching implications


Man, that makes me want someone to go drill core samples through a few of them. There are a couple private companies claiming that they intend to do some prospecting and maybe mining. Whether that actually happens or not, if they are at least able to go collect samples, it would be a boon for science. I'm sure there are research agencies who would pay good money for pristine asteroid samples. At least for the forseeable future, samples will be worth more for their scientific value than for their mineral value, even if they are made of diamond and platinum. That is even more the case for comets, since we already have some pieces of asteroids that survive falling to Earth, but we have no real samples of a comet (those dust specks they got don't count). A private company should be able to fully fund a sample mission with paying science customers.
ViperSRT3g
5 / 5 (5) Feb 05, 2014
Yarkovsky-O'Keefe-Radzievskii-Paddack (YORP) effect


Wouldn't it be easier on the eyes if it were the following: Paddack-Yarkovsky-Radzievskii-O'Keefe (PYRO) effect. Especially since this deals with heat being emitted from a body in space.
antialias_physorg
5 / 5 (3) Feb 05, 2014
Man, that makes me want someone to go drill core samples through a few of them

In cases like this it might be even easier - as there may be exposed 'interiors' at the interface of the two parts (if it was formed by a collision, that is)

Wouldn't it be easier on the eyes if it were the following: Paddack-Yarkovsky-Radzievskii-O'Keefe (PYRO) effect.

Since it's based on the long established Yarkovsky effect it only seems fitting to keep his name first.
http://en.wikiped...y_effect
TheGhostofOtto1923
3 / 5 (2) Feb 05, 2014
but we have no real samples of a comet (those dust specks they got don't count). A private company should be able to fully fund a sample mission with paying science customers.
-Until you get your own AI it's always prudent to research your notions before posting them rather than relying on the people here to do it for you.

"First Evidence Found of a Comet Strike on Earth
Comet exploded 28 million years ago over Egypt... A tiny slice of the black pebble was put through isotopic analysis, which definitely ruled out that it came from a meteor. Instead, the analysis showed that the pebble possessed the unique chemical signature of a comet, measured in terms of elements such as argon and carbon."
GSwift7
5 / 5 (3) Feb 05, 2014
Until you get your own AI it's always prudent to research your notions before posting them rather than relying on the people here to do it for you


First, that's just one pebble. Are all comet pebbles just like that one?

Second, it was cooked while going though the atmosphere. Did that change it?

Third, the rocky component of comets is only part of what they are made of. What kind of volatiles and possibly organics will we find on a comet?

Fourth, it has been laying around the surface of the Earth since it fell, allowing contamination and weathering.

So, that doesn't qualify as a real sample of a comet by any stretch of the imagination. Also, my post said that I was aware that we have small bits of comets, so your comment fails. Don't you have some comic books to read or something? Maybe you can go work on your FTL drive or your space elevator design.
cantdrive85
1 / 5 (6) Feb 05, 2014
schematic view of the strange peanut-shaped asteroid Itokawa

It's not really that strange, we see it with comets like Hartley and Borrelly
And we see it created in laboratory such as CJ Ransom has done;

http://www.thunde...eyBW.jpg

http://ieeexplore...=4287076

It's only "strange" when all you have to work with is gravity.
TheGhostofOtto1923
3 / 5 (2) Feb 05, 2014
First, that's just one pebble. Are all comet pebbles just like that one.... etcetcetc
Non sequitur. You said
but we have no real samples of a comet (those dust specks they got don't count)
-and so all I needed to do was find one real sample in order to show that you didnt bother to look brfore making the statement. Which is an unfortunate habit yes? Are you an old dog?
So, that doesn't qualify as a real sample of a comet by any stretch of the imagination.
SURE it does. A singular, cooked, rocky, and weathered example of one. Perhaps your imagination unable to stretch very far.
my post said that I was aware that we have small bits of comets
-No, your post said
those dust specks they got don't count
What? Did you think your post was too far up the thread for checking again?
TheGhostofOtto1923
3 / 5 (2) Feb 05, 2014
Even this statement of yours isnt true.
First, that's just one pebble. Are all comet pebbles just like that one
The scientists from the article I cited make the distinction.

"Microscopic dust particles from these icy interlopers have been collected from the upper atmosphere and from Antarctic ice, and have been scooped up by space probes.

"But having a chance to study sizable comet material firsthand would be exceptional, and Block and his team believe it can offer a unique chance to study the birth of our solar system.

""My bet is that this little rock will unlock some unique secrets in time to come, specifically because it appears packed with presolar grains," said Block."

1) You didnt search to check your notions before posting them, and
2) You didnt read the article I referenced which confirmed that we now have 2 distinct classes of objects; DUST grains, and this pebble, which the scientists regard as SIZABLE.

-And so you were lazy twice.
Captain Stumpy
5 / 5 (4) Feb 05, 2014
@cd
first link= pretty picture, verifies nothing
second link= references spherules in or around the craters etc
your references are from a known crackpot site that supports PSEUDOSCIENCE and is not worth anything
HOWEVER, if you would like to find references from legitimate sites that may corroborate & give experimental evidence of these fantastically large discharges that make said craters... feel free

I will warn, though, that perfectly plausible explanations like collisions with other asteroids/bodies in space are more abundant

given your intellectual stagnation in the EU hypothesis, I would suggest further education before attempting to elucidate the EU further on the site as it only reaffirms your ignorance to astrophysics and the knowledge that is involved

especially in light of your recent accusations against J. Hlavacek-Larrondo which were directly refuted and proof offered for you to peruse

PS no evidence in your links supporting EU as shaping this asteroid either
GSwift7
3 / 5 (4) Feb 05, 2014
You know what I meant, and that I'm right. You are being a disruptive troll, as usual, and I'm right about that as well. Go watch some Star Trek episodes and drink energy drinks in your mom's basement while you grief the kids playing an online shooter game or something. I really couldn't care less for your nonsense posts.
TheGhostofOtto1923
3 / 5 (2) Feb 05, 2014
You know what I meant, and that I'm right.
No, its not right to post without doing a little work first. You were totally unaware of that valuable little rock, as was I. But you were the one who missed the chance to learn something new.
You are being a disruptive troll, as usual
1) Science thrives on the details and
2) Scientists have to be diligent in constantly checking for recent discoveries in their fields to make sure their knowledge base is current. We amateurs should be doing the same dont you think?
I really couldn't care less for your nonsense posts
But I do care when people like you do not post responsibly, and will continue to object and to correct such sloppiness. Because it is rewarding and fun.
cantdrive85
1 / 5 (6) Feb 05, 2014
Stumpy, your obviously a moron!
Now the experimentally backed papers published by the IEEE Transactions on Plasma Science are pseudo? I must say you will have a difficult life going forward if you insist that scientific discoveries made by engineers are "pseudo". You apparently didn't read the paper that described the extensive discoveries by electrical engineers in the various areas of astrophysics.

PS no evidence in your links supporting EU as shaping this asteroid either

That "pretty picture" shows two objects, one created by electric discharge in a lab, the other is a well studied comet. The fact there is only way to experimentally reproduce that object isn't enough? You'd prefer to rely on theoretical models in favor of rock solid experimental evidence? Nothing need more to be said, it's obvious you are far dumber than the rocks we speak of....
aroc91
5 / 5 (9) Feb 05, 2014
your obviously a moron!


Irony.
Captain Stumpy
5 / 5 (2) Feb 05, 2014
no evidence in your links supporting EU as shaping this asteroid either

@cd
Still no evidence
your EU has no relevance
your speculation that astrophysics has not learned anything in 30+ years with your proclamations that EU describes everything are nothing more than unfounded conjecture based upon the ramblings of a mechanical engineer that has no comprehension of astrophysics
Nothing need more to be said, it's obvious you are far dumber than the rocks we speak of

funny, you still havent accounted for how said discharge happened in the plasma and why we didnt see said discharge,
nor why we STILL dont see discharges continually making/shaping new comets

we DO see other comets and collisions in the solar system and the standard model CAN account for what we observe
EU=useless here

PS discharges that made/shaped said rock would leave evidence that would have showed up with the scans, and there is no mention of that here, is there?
NOPE
Captain Stumpy
5 / 5 (2) Feb 06, 2014
The fact there is only way to experimentally reproduce that object isn't enough

@CD
wait... so are you saying that the ONLY way to reproduce this object would be with your EU hypothesis? REALLY?
You'd prefer to rely on theoretical models in favor of rock solid experimental evidence?

first: I trust experiments
BUT I trust your links about as far as I can throw my house
second: given your propensity to completely IGNORE studies and experimental evidence that is put forth from REPUTABLE sites, I find is downright hilarious for you to make this particular comment...
as aroc91 says "Irony"!

more to follow RE: your links

Captain Stumpy
5 / 5 (2) Feb 06, 2014
@CD85
Lastly
your link refers to
Plasma discharges that produced craters in various materials often created spherules in or around the craters. Both individual spherules and joined spherules were created

this does NOT address asteroid formation
also, this is about plasma making craters in various materials
its hidden behind a paywall so we cant see results
AND
it most likely deals with materials and testing here on earth and there are obviously NO observations NOR are there any cosmological applications unless within the delusion of EU and CRACKPOT PSEUDOSCIENCE leaving me to only speculate about the results and what materials were involved
and again... given the nature of plasma and the materials of the asteroid, there is a known pattern of behaviour that would allow the researchers/observers to make pronouncements as to plasma shaping/formation of said asteroid as the evidence would be visible/known from the scans
THEREFORE no proclamations or supporting evidence for EU here
GSwift7
5 / 5 (1) Feb 06, 2014
You were totally unaware of that valuable little rock,


Actually, I was aware of it. As with anything like that, the first such sample always makes big news. However, in science, sample size bias is a problem when you only have one sample. One single, tiny sample is both invaluable and worthless at the same time. As the first sample, it proves that others might be found on Earth. But as a one-of-a-kind, there's no way of knowing how typical it is. What if that piece survived due to the fact that it's very different from 'normal' comet material? There's no way to know. As such, we really don't have a representative sample from a known comet. Obviously, the piece they found is from a comet that doesn't even exist any more, so we will never know more about it. When I say "a real sample" that means knowing where it came from and knowing whether it is a representative sample or not, and that it's a complete, pristine sample, not a burnt fragment.
GSwift7
5 / 5 (1) Feb 06, 2014
But I do care when people like you do not post responsibly, and will continue to object and to correct such sloppiness


Nobody wants to read five successive posts giving every known detail of current comet research. In the 1000 word limit, normal people understand that we use generalizations, such as 'most', 'sometimes', etc. In this case I qualified my remark with the phrase "no REAL samples'. By reading that, most people would understand that we do have some samples, and that I chose not to list them all out in detail, but that my opinion was that those samples aren't very good. You see, you may not like my grammar, but I don't care. Again, this is just an internet forum and there's a 1000 word limit. I'll be as casual as I care to, and most people seem to understand perfectly well. If you think it's fun griefing people on forums, then maybe you should rethink your entertainment options.