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Thread: Asteroid Psyche

  1. #1
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    Asteroid Psyche

    I've been reading about NASA's mission to the asteroid Psyche. This asteroid is described as almost pure iron/nickel and is likely to be the core of some ancient protoplanet. My question is this - iron and nickel have densities of just under 8g/cc but Psyche's density is less than half this at 3.3g/cc. So how can it be described as almost 100% iron/nickel? Is there a lot of rocky material present or is it porous?

  2. #2
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    Here is a paper by D. F. Lupishko discussing "On the bulk density of the M-type asteroid 16 Psyche"
    And I think "yes" on the porosity assumption leading to the low mean density (as also in the abstract).
    the paper is behind a pay wall, but I should have a pdf of it at work.
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  3. #3
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    Asteroid Psyche

    Quote Originally Posted by tusenfem View Post
    Here is a paper by D. F. Lupishko discussing "On the bulk density of the M-type asteroid 16 Psyche"
    And I think "yes" on the porosity assumption leading to the low mean density (as also in the abstract).
    the paper is behind a pay wall, but I should have a pdf of it at work.

    Thank you for your reply - the abstract of the paper was sufficient for my purposes . I don't need the full paper but does it say where the porosity came from? If it had been the core of an early planet then it would have very little porosity. Presumably Earth's core would have close to zero porosity. Perhaps dissolved gases ar erelased from the metal.

  4. #4
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    I think there is also some water ice there. Perfect. Metal and fuel.
    https://phys.org/news/2016-11-pure-m...-deposits.html

  5. #5
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    Maybe the asteroid has a highly porous exterior, which puffs out its radius. I suppose it's also possible that the asteroid got smashed and cooled early in its differentiation process, so didn't have time for all the gas bubbles to float up and out of the core. Another possibility is that the object is a metallic "rubble pile", which can happen if the metallic core is pulverized into little droplets which cool and solidify before they remerge, giving you the porosity of packed spheres. Sounds like they are still puzzling over this object.
    Last edited by Ken G; 2017-Jun-17 at 02:13 PM.

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