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#1 2017-04-01 17:19:12

RobertDyck
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From: Winnipeg, Canada
Registered: 2002-08-20
Posts: 5,882
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What is the source of metal asteroids/meteors?

I have a question? What is the source of metal asteroids and meteors?

I'm told that during the early solar system, a body of some sort must have formed. The body would have had to be large enough to melt the core and mantle, and enough gravity to cause molten metal to sink to the core. At some point a collision caused that ancient body to break up. That metal is the source of all metal asteroids and meteors today. The crust of that body would have been depleted of metal, only stone. The crust of that body is the source of stony asteroids and meteors today.

But to do all that, the body couldn't be just another asteroid. It had to be large enough to melt the core, and for metals from the mantle to sink to the core, it had to be hot enough to melt the mantle as well. And it must have had enough gravity to differentiate material. On Earth, our planet's core is believed to be mostly iron, but probably has other metals like nickel. Rocks of our crust are mostly alumina-silicates. That means silicon oxide, aluminum oxide, and mostly a combination of aluminum and silicon and oxygen. These lighter minerals float to form the crust. Yea, relative to iron and nickel, solid rock is light. Using today's terminology, such a body would have had to be at least a dwarf planet. That means a body large enough for gravity to squash itself into a sphere.

So what was it? Are all metal meteoroids from one single dwarf planet that broke up? Did more than one break up? How common was the break-up of an entire planet, dwarf or otherwise? Asteroid "16 Psyche" has been found to be metal. The same metal as a metal meteorite here on Earth. Meteorites are not all the same, there are significant differences. However, there are differences in rocks here on Earth, so could different spots of that ancient planet that broke up also have had differences? The same differences that cause meteorites we see today? Is asteroid "16 Psyche" the remnant of the ancient planet that is the source of all smaller metal asteroids and meteoroids/meteorites? Or was there more than one source?

Is a dwarf planet large enough to form a metal core as large as "16 Psyche"? That's a lot of metal. Or did a full-size planet break up to form that?

Since Apollo, scientists believe the source of the Moon was collision of a planet with Earth. That other planet was about the size of Mars, most of which was absorbed by the Earth. That was the last major impact event that formed our planet. Some of the crust of our planet, and probably some of the crust of that other planet got thrown into space. They believe it formed a ring around Earth, which coalesced to form the Moon. That was fairly quick in geological terms: about 10 million years. Much of the debris thrown into space would have fallen back to Earth, making the Earth bigger. But here's another question: Could some of the metal meteors we see today be from the core of that other planet? Could the impact that created the Moon have been violent enough to break off pieces of the smaller planet's core, throw those into space? Are they still falling to Earth today?

"16 Psyche" is in the main belt, so it didn't come from Earth. "Theia" is currently accepted name for the planet that collided with Earth to form the Moon, which in Greek mythology was a titan, mother of Selene who was goddess of the Moon. So "16 Psyche" could not have come from Theia. But where did it come from?

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#2 2017-04-01 19:12:56

Tom Kalbfus
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Registered: 2006-08-16
Posts: 4,401

Re: What is the source of metal asteroids/meteors?

I believe the Asteroid Belt used to be much wider than it is today, most of those asteroids collided with the planets or were thrown out of the Solar System altogether, the remnants of that are the Asteroid Belt the Kuiper Belt and the Oort Cloud there were obviously a lot of collisions during the formation process. There may have been some shattered planets in the mix, after all the collision of Thea with Earth might have resulted in the shattering of Earth itself, other planets might have been blown apart altogether, and maybe reformed later, maybe leaving remnants of itself in the asteroid belt for instance.

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#3 2017-04-02 04:13:08

elderflower
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Registered: 2016-06-19
Posts: 1,169

Re: What is the source of metal asteroids/meteors?

In the early solar system there was a lot more heat available from decaying, relatively short half life nucleotides than remains now. Sufficient to melt the cores of much smaller bodies than the current crop of dwarf planets.

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#4 2017-04-02 08:01:23

Terraformer
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From: Lancashire
Registered: 2007-08-27
Posts: 3,205
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Re: What is the source of metal asteroids/meteors?

What elderflower said. Isotopes like Aluminium-26 produced enough heat that even small bodies were able to differentiate, and when they smashed into each other, the different parts went on their way.

That said, 16 Psyche is massive enough that it must have been the core of a dwarf planet, surely...


"I guarantee you that at some point, everything's going to go south on you, and you're going to say, 'This is it, this is how I end.' Now you can either accept that, or you can get to work." - Mark Watney

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#5 2017-04-03 04:45:04

elderflower
Member
Registered: 2016-06-19
Posts: 1,169

Re: What is the source of metal asteroids/meteors?

I think you are right there, Terraformer. It must, however, have solidified before the impact that blew away the rest of its planetoid, otherwise it too would have been sprayed all over the solar system instead of being one large piece.

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#6 2017-04-03 17:31:15

SpaceNut
Administrator
From: New Hampshire
Registered: 2004-07-22
Posts: 17,844

Re: What is the source of metal asteroids/meteors?

Here are the boards 3 other topics....

Psyche and Lucy Missions with just the opening post

Giant Metallic Asteroid Psyche may have water with 10 replies

16 Psyche with 8 reply posts

Maybe we have covered some of the question but we also may have created some more....

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