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Why Hasn't This Asteroid Disintegrated?
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.
Give me a nuke, Bruce Willis, Steve Buscemi, and Sad Batman, and I'll make sure that asteroid is good and proper disintegrated!
...that's a space station!
Mystery solved.
"Once we've identified and embraced our sickness, we'll have strength...and that's when we get dangerous." - John Waters
Not an asteroid....
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?
"You're right," Fisheye says. "I should have set it on 'whip' or 'chop.'"
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.
how do they work?
Maybe all the rocks already flew off due to the spin, and that's why we aren't seeing that happening.
Maybe it doesn't know any better. Rocks aren't exactly known for their keen intelligence.
Perhaps some giant space creature consumed plenty of fiber...
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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This is totally unacceptable!!!
TFS says that vdW interactions are interactions between polar molecules... that's absolutely false! The reason water has a high surface tension is due to hydrogen bonding, which is a combination of polar interactions and charge transfer. The reason that polar molecules attract is entirely due to electrostatic reasons... electric dipoles aligning causing favorable interactions. Van der Waals interactions are when NON-polar molecules spontaneously polarize one another to form instantaneous dipoles, which attract electrostatically. The key here is that vdW attractions occur even in molecules that do not have any static dipole... the dipole-dipole interactions are dynamic and fluctuating. One of the hallmarks of vdW interactions are their asymptotic behavior. Charge-charge interactions die off as r^-1. Dipole-dipole interactions die off as r^-3. vdW interactions die off as r^-6.
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.
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Betteridge's Law says no.
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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
In other words things can stick to other things. Who would have thought?
If it's been spinning like that all along then surely it would have no debris left on it to eject into space? When exactly did it start spinning? Oh, You don't know...
Holy shit! Sun used to be hardcore!
Forget magic. Any technology distinguishable from divine power is insufficiently advanced.
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 not the elliptic plane .
That said, you are likely correct that the asteroid formed via accretion in the protoplanetary disk, rather than being ejected from a supernova.
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.
No, no, you're not thinking; you're just being logical. --Niels Bohr
Beyond this limit, outward centrifugal forces...
I stopped reading at this point unless the writer can explain where these mysterious "centrifugal" forces emanate from.
I am becoming gerund, destroyer of verbs.
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?
Dark Matter, the Aether, Either, ect.
Technically, all iron and nickel is the byproduct of a supernova explosion, as only stellar fusion is energetic enough to generate such heavy elements, and only a supernova is powerful enough to launch those elements clear of the star's gravity well. However, the concept that a mass of iron and nickel could survive such an event as a coherent slug is laughable.
Ecliptic.
Presumably, you meant the ecliptic
No. From reference.com:
elliptic. 1. pertaining to or having the form of an ellipse.
Double down on the derp, Cowboy!
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 "plane of the ecliptic" or the "ecliptic plane" not the "elliptic plane."
I'm sorry I got your panties in a bunch, but you were incorrect. Call me an Astronomy Nazi if you like, but nomenclature is relevant, IMHO.
No, no, you're not thinking; you're just being logical. --Niels Bohr
I like online games where there's PvP and more than one character in your arsenal. It's even better when you have a username like Van der Waal, because then your forces are, logically, Van der Waal's forces.
Thank you, thank you, I'll be here all night, or until the drinks run out.
Let's destroy it by launching dinosaurs at it.
Table-ized A.I.
Something about a "Rendezvous " or something with "Rama" or the like. It's been awhile.
Senior NCO in the fight against entropy. I've seen things, man. Things no one should have to see.....
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 = 0.0003315m/s/s.
Centrifugal Force = 0.00040915m/s/s
While that relates to the orbital speed calculated for the mass and radius of 0.4642m/s, it is far less than the escape velocity of 0.6565m/s. 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 surface and point it straight upwards and accelerate it with the gravity of 0.0003315m/s/s then it would come to a stand-still in somewhere over 1600seconds at a height somewhere over 800m and fall back towards the asteroid.
I don't know the maths to figure out the exact values since they vary so greatly with distance, but the difference in centrifugal and gravitational force is only 0.00007765m/s/s. That means that something weighing 100 TONS on earth would have a net upward force of about 1.6 pounds. Of course you can't treat the asteroid as discrete frictionless atoms. What holds a dirt clod together overcoming the full force of earth's gravity to maintain it's shape?
So if you were attached to the surface and dropped a rock it seems to me that it should continue upwards and orbit the asteroid at some altitude. It doesn't surprise me though that since dust can stick to my ceiling and ceiling fan blades even when they're whirring around that this asteroid can stick together.
I would conclude that this was part of a larger body. It is a solid rock because it was molten at some point in its history. Probably resulted from a larger collision.
There are a number of electric planes... air planes that is :)
'Nuff said.
Maybe it's got a quantum black hole at it's center, and it's just big enough to provide sufficient gravity to prevent debris on the surface from departing, but small enough that it's not rapidly consuming the asteroid yet?
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