Why Hasn't This Asteroid Disintegrated? 74
sciencehabit writes: Planetary scientists have found an asteroid spinning too fast for its own good. The object, known as 1950 DA, whips around every 2.1 hours, which means that rocks on its surface should fly off into space. What's keeping the remaining small rocks and dust on the surface? The researchers suggest van der Waals forces, weak forces caused by the attraction of polar molecules, which have slightly different charges on different sides of the molecule. For example, water molecules exhibit surface tension because of van der Waals forces, because the negative charge of one water molecule's oxygen atom is attracted to nearby water molecules' hydrogen atoms, which have a positive charge at their surfaces. Similar attractions could be occurring between molecules on the surfaces of different pieces of dust and rock. Such forces would be comparable to those that caused lunar dust to stick to astronauts' space suits.
No Disintegrations (Score:5, Funny)
Give me a nuke, Bruce Willis, Steve Buscemi, and Sad Batman, and I'll make sure that asteroid is good and proper disintegrated!
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You forgot Michael Clarke Duncan
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He sadly passed away :(
That's no asteroid... (Score:5, Funny)
...that's a space station!
Mystery solved.
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Perhaps some giant space creature... (Score:2)
Perhaps some giant space creature consumed plenty of fiber...
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The correct answer is that Marvin the Martian lost his lludium Q-36 Explosive Space Modulator, and wasn't able to blow it up.
RAMA (Score:3, Funny)
Not an asteroid....
Why can't it just be one mass? (Score:5, Interesting)
The article doesn't explain why the idea of this particular body being one mass instead of a rubble pile has been dismissed. Is there a good one?
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...or the possibility that the core is some ultra dense material making all those fancy gravity equations balance out! ...or because that's how the aliens who sent it want it to behave!!
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That thought was the very first thing that crossed my mind.
I mean the only super dense stuff that I've read about is ultra-dense deuterium
( It's in the range of 100+ tons/ cm3 ) but it's only produced in really small quantities
I would really enjoy knowing if something ultra dense is produced, and how does it effect gravity. I think that would be a fun project
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The core is pure eezo, and this has caused a mass-effect field to form, significantly increasing the mass of the asteroid...
What?
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Yea the article dismisses out of hand what seems like the simplest answer, that they're solid chunks of rock or metal.
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Or that they're frozen on or otherwise stuck. Stuff sitting on a table, shelf, or floor gets stuck there by other crud.
Re:Why can't it just be one mass? (Score:5, Insightful)
Results of a new study (Busch et al.) combining the 2001 Goldstone and Arecibo radar data with optical lightcurves are presented in the journal Icarus. Shape, spin state and surface structure of 1950 DA are estimated. New observations intended to resolve the prograde/retrograde spin issue were inconclusive, therefore two distinct shape models are presented. One rotates in a prograde sense and is roughly spheroidal with a mean diameter of 1.16 +/- 0.12 km. The other rotates in a retrograde sense, is oblate, and about 30% larger. Both models suggest a nickel-iron or enstatite chondritic composition. [nasa.gov]
So, since it has been established that the asteroid in question is pretty much a chunk of metal, and the rate of rotation would be fast enough to dislodge independent pieces of material, the obvious answer is "the rubble already flew off, this is a big hunk of nickel-iron." After doing that bit of research, I don't care what is in the summary or the article behind this story, they'd better show up with a good argument that this piece of metal has any rubble clinging to it before I will waste the effort considering other explanations.
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Not worth it. It is so expensive with the current technology that it would be cheaper and easier to refine similar amount here on Earth
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a 1.3km sphere of iron would mass over 9 billion tons, nickel would be even heavier. It would be easier to bring the foundry to it, rather than the other way around.
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The article doesn't explain why the idea of this particular body being one mass instead of a rubble pile has been dismissed. Is there a good one?
Asteroids are believed to be aggregations of relatively loosely bound matter. They have likely experienced some local melting due to collisions, but it is very unlikely that they ever were entirely melted into a single mass. As such, they are quite peculiar bodies, much less akin to a mountain than a pile of rubble, and they likely aren't even all that close to a pile of rubble because the individual components they are made from were never part of a larger, more coherent body.
If you think about asteroid fo
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Some Asteroids are believed to be aggregations of relatively loosely bound matter.
FTFY. Some asteroids are differentiated masses that were clearly molten at some point in their history. Some are fragments of larger bodies that were broken up.
Molten piece of crystalline rock with ionic bonds (Score:3, Interesting)
What's keeping a piece of rock that used to be molten lava together? Crystalline ionic attractive forces. Van der Waals forces would not be strong enough to keep such an asteroid together, and that's proof that the whole thing flew off as one piece from some supernova explosion. Maybe that's the idea of catching these asteroids with spacecraft - see what stuff looks like coming straight out of a supernova, as opposed to stuff that has been impact pounded into the Moon's surface, or glowing-hot shooting star thermally remelted on the Earth's surface. The stuff that lands on Earth is mostly remnants of shooting stars that did not completely combust, but there might be some meteorite rocks that were traveling with speed close to that of Earth on rendezvous, and only attained terminal velocity in the atmosphere that's not fast enough to melt them. So some meteorites that land on the Earth could be very similar to a captured asteroid out there, and a lot cheaper. Another aspect of capturing an asteroid is practice: for when we have to capture stuff in space to build space stations out of them. Space is very very empty, huge distances of vacuum with very little stuff sprinkled here and there. Any stuff, any matter, is worth gold in outer space, especially away from a gravity well like Earth or Jupiter, but the Moon is better.
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the whole thing flew off as one piece from some supernova explosion
I didn't read TFA but is it's in the elliptic plane, cruising along in the same general direction as everything, it originated in this solar system.
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Holy shit! Sun used to be hardcore!
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the whole thing flew off as one piece from some supernova explosion
I didn't read TFA but is it's in the elliptic plane, cruising along in the same general direction as everything, it originated in this solar system.
Presumably, you meant the ecliptic [wikipedia.org] not the elliptic plane [wolfram.com].
That said, you are likely correct that the asteroid formed via accretion in the protoplanetary disk [wikipedia.org], rather than being ejected from a supernova [arxiv.org].
Regardless, it's quite an interesting conundrum. I suppose it's possible that high-energy collisions melted the material which would become the asteroid and it coalesced into solid chunk(s) which are unaffected by the high rotation rate.
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Presumably, you meant the ecliptic
No. From reference.com:
elliptic. 1. pertaining to or having the form of an ellipse.
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Presumably, you meant the ecliptic
No. From reference.com:
elliptic. 1. pertaining to or having the form of an ellipse.
You're still not correct, but I should have said "plane of the ecliptic," (or "ecliptic plane") rather than just "ecliptic." My apologies for any confusion. However, "elliptic plane" refers to any planar ellipsoid surface, while "plane of the ecliptic" specifically refers to the region in which the sun and the vast majority of other matter in our solar system resides.
That region is a three-dimensional ellipsoid (an example of a planar surface in the shape of an ellipse), is correctly referred to as the " [universetoday.com]
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it's in the elliptic plane,
It might be in the epileptic plane (so its shaken and not stirred). I dont think anyone has an electric plane yet. Airbus might be considered an eclectic plane. Or perhaps you meant the ecliptic plane?
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Ecliptic.
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fucking magnets (Score:5, Funny)
how do they work?
Or maybe... (Score:1)
Maybe all the rocks already flew off due to the spin, and that's why we aren't seeing that happening.
Why Hasn't This Asteroid Disintegrated? (Score:5, Funny)
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My pet rock says otherwise, you insensitive clod!
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My pet rock says otherwise, you insensitive clod!
My dog just said, "Video, or it didn't happen." ;-)
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https://www.youtube.com/watch?v=0H6XEfRnwhg
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That's not what van der Waals is! (Score:5, Informative)
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You're lucky Slashdot doesn't have a "-1: Basic Grasp of Relevant Concepts", because I'm sure you'd be modbombed by it.
Maybe I'm just old, but I'm really sick of seeing articles, interviews, etc. where the "expert", often times an actual degree-wielding scientist, gets fundamental concepts completely wrong. Every time I hear someone explain lift with "air on the top of the wing has to move faster, so... lift!" I want to defecate into their open mouths.
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You are a hateful, spiteful old bastard.
You say that like it's a bad thing.
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I'm not sure I know what you mean. Where have I failed to grasp the relevant concepts? I'm merely criticizing the mistaken impression that TFS (which is apparently lifted directly from TFA) gives about what vdW forces are.
I'm saying you do exhibit a basic grasp of relevant concepts, that on Slashdot people who are correct usually get shat upon, and that the "experts" in TFA often don't have a basic grasp of the relevant concepts, as your post illustrates.
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Every time I hear someone explain lift with "air on the top of the wing has to move faster, so... lift!" I want to...
There's nothing at all wrong with that explanation. It is neither better nor worse than any other explanation that is less than a full solution to the Navier-Stokes equation, and it provides a naive and surprisingly practical guide to interacting with airfoils, which the vorticity explanation, for example, does not.
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Air doesn't have to "move faster". Viewing the profile of a wing and using it as a fixed reference point, the air on top doesn't have to move faster in the horizontal plane at all, it just has to be deflected. Air moving at a velocity (or a relatively faster one) doesn't create a force. Air moving faster than other air doesn't create lift.
What creates lift is the deflection of air. This is achieved by the angle of attack of the wings. When air has to change direction there's acceleration, and thus forc
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Of course, that still makes the summary wrong, but differently wrong.
Conspiracy (Score:2)
Such forces would be comparable to those that caused lunar dust to stick to astronauts' space suits.
Ohh stop it! Now after so many years we should just admit the dust was sticking because they were too hasty starting to use the new set in the area 51 studio's and the black paint hadn't yet fully dried.
No (Score:3)
possible answers (Score:2)
1. said rocks are seeking their 'natural place', and have found it
2. spinning does not lose you any weight
3. surface friction in the horizontal plane
So... (Score:1)
It's centripetal stupid (Score:2)
Beyond this limit, outward centrifugal forces...
I stopped reading at this point unless the writer can explain where these mysterious "centrifugal" forces emanate from.
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I did. Rotating mass is subjected to its own inertia. No "force" is pulling it outward.
Sweet Revenge (Score:1)
Let's destroy it by launching dinosaurs at it.
Didn't I read about this once? (Score:2)
Where do they get 2.2 hours from? (Score:2)
The article makes it sound like it doesn't matter what size or mass.
Parameters: Radius 650m, Circumference 4084m, Period 7560s, Speed 0.5157m/s, Mass 2.1e12kg
Calculating Surface Gravity [wikipedia.org] = 0.0003315m/s/s [google.com].
Centrifugal Force [wikipedia.org] = 0.00040915m/s/s [google.com]
While that relates to the orbital speed [wikipedia.org] calculated for the mass and radius of 0.4642m/s, it is far less than the escape velocity [wikipedia.org] of 0.6565m/s [google.com]. So how far out would it go?
The numbers are so small that if you take the speed they are moving of 0.5157m/s tangental to the surf
Dark Matter (Score:2)
'Nuff said.
Quantum black hole? (Score:2)