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Thread: Stability of a rotating asteroid housing a space station

  1. #1
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    Default Stability of a rotating asteroid housing a space station

    Today there are numerous studies on asteroid mining. They elaborate on selecting the right objects, prospecting missions, potential asteroid redirection, and the mining process itself. For economic reasons, most studies focus on mining candidates in the 100-500m size-range. Also, suggestions regarding the design and implementation of space stations or even colonies inside the caverns of mined asteroids exist. Caverns provide the advantages of confined material in near-zero gravity during mining and later the hull will shield the inside from radiation. Existing studies focus on creating the necessary artificial gravity by rotating structures that are built inside the asteroid. Here, we assume the entire mined asteroid to rotate at a sufficient rate for artificial gravity and investigate its use for housing a habitat inside. In this study we present how to estimate the necessary spin rate assuming a cylindrical space station inside a mined asteroid and discuss the implications arising from substantial material stress given the required rotation rate. We estimate the required material strength using two relatively simple analytical models and apply them to fictitious, yet realistic rocky near-Earth asteroids.
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    Hope the voyage is a long one.
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    Default Re: Stability of a rotating asteroid housing a space station

    Interesting.

    What are you doing about it?




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    Default Re: Stability of a rotating asteroid housing a space station

    For the human body, any gravity is better than no gravity -- if you want to come back to a planet again. That's why the Zubrin plan for Mars incorporated a detachable engine, which (after Mars Orbit Insertion burn) would be strung out on a long wire cable, for a mutual-rotation during the 6-month cruise. Then cut free when near Mars.

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    Default Re: Stability of a rotating asteroid housing a space station

    Read the article. I want to be a miner.
    Life is complex.

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    Default Re: Stability of a rotating asteroid housing a space station

    Haven’t read the article but it would seem valuable to have self-repairing machines since animal labor isn’t doing the work and all the hardware is coming from Earth for what could be long duration excavation projects. There’s a limit to redundancy and spare parts.

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    Default Re: Stability of a rotating asteroid housing a space station

    On a spinning asteroid one would be mining up, instead of down, with respect to 'gravity'

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    Default Re: Stability of a rotating asteroid housing a space station

    A practice used in The Expanse.
    The definition of stupid has got to be the belief that more guns will negate the bloodshed done with guns.

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    Default Re: Stability of a rotating asteroid housing a space station

    Quote Originally Posted by David W Pratt View Post
    On a spinning asteroid one would be mining up, instead of down, with respect to 'gravity'
    Not if you mine from inside, out.

    Hope the voyage is a long one.
    May there be many a summer morning when,
    with what pleasure, what joy,
    you come into harbors seen for the first time...

    Ithaka, by Cavafy
    (Keeley - Sherrard translation)

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    Default Re: Stability of a rotating asteroid housing a space station

    Quote Originally Posted by LeeG View Post
    Haven’t read the article but it would seem valuable to have self-repairing machines since animal labor isn’t doing the work and all the hardware is coming from Earth for what could be long duration excavation projects. There’s a limit to redundancy and spare parts.
    3D printer could answer a lot of those questions.

    In fact, it would seem possible to take a worn-out, register it top the printer platen, and print the worn surface anew.

    . . .


    I can see an large asteroid/small moon made of some substance that is easily-convertible into 3D printer 'ink', turned into an interplanetary machine factory.

    Print up some SolarWind® engines, and go make the rounds keeping the Solar System's industrial base in working order.
    Rattling the teacups.

  10. #10
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    Default Re: Stability of a rotating asteroid housing a space station

    Quote Originally Posted by oznabrag View Post
    3D printer could answer a lot of those questions.

    In fact, it would seem possible to take a worn-out, register it top the printer platen, and print the worn surface anew.

    . . .


    I can see an large asteroid/small moon made of some substance that is easily-convertible into 3D printer 'ink', turned into an interplanetary machine factory.

    Print up some SolarWind® engines, and go make the rounds keeping the Solar System's industrial base in working order.
    the Replicator!

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    Default Re: Stability of a rotating asteroid housing a space station

    There is a problem, here.

    Very small asteroids can spin fast, because they're generally monolithic. Most asteroids spin slowly, because they're not. Their gravity is too low to maintain a cohesion between lumps 'n' chunks of matter, which would otherwise get flung off at high rotation speeds.

    Take Ceres, the biggest. Surface gravity is <3% of Earth. With a day length of 9 hours, the equator is zipping around at 90 m/s. Escape velocity there is 500m/s. Spin Ceres up to just under its falling apart velocity, and you get a mighty 14%Earth g. Less within it.

    The paper requires big 500m(?) lumps of rock to work. I'm not at all sure asteroids are like that. Here's Ryugu:



    You can guess the spin axis. It's a pile of barely-stuck-together junk.

    Andy
    "We were schooner-rigged and rakish, with a long and lissome hull ..."

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    Default Re: Stability of a rotating asteroid housing a space station

    no claustrophobics allowed
    Xanthorrea

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    Default Re: Stability of a rotating asteroid housing a space station

    Quote Originally Posted by AndyG View Post
    There is a problem, here.

    Very small asteroids can spin fast, because they're generally monolithic. Most asteroids spin slowly, because they're not. Their gravity is too low to maintain a cohesion between lumps 'n' chunks of matter, which would otherwise get flung off at high rotation speeds.

    Take Ceres, the biggest. Surface gravity is <3% of Earth. With a day length of 9 hours, the equator is zipping around at 90 m/s. Escape velocity there is 500m/s. Spin Ceres up to just under its falling apart velocity, and you get a mighty 14%Earth g. Less within it.

    The paper requires big 500m(?) lumps of rock to work. I'm not at all sure asteroids are like that. Here's Ryugu:



    You can guess the spin axis. It's a pile of barely-stuck-together junk.

    Andy
    A good reason to survey asteroids, isn't it? I'd start with the bigger NEOs, and work out into the Belt.

    While little is known on material properties of small asteroids subject to our study, we rely on assumed material strength. Here, we assume that the asteroid is made of homogeneous, solid material such as basaltic silicate rock, for instance. We estimate the load on the asteroid material in simplified models: the tensile stress acting on the asteroid cross section is related to assumed tensile strength of solid silicate rock.

    Hope the voyage is a long one.
    May there be many a summer morning when,
    with what pleasure, what joy,
    you come into harbors seen for the first time...

    Ithaka, by Cavafy
    (Keeley - Sherrard translation)

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    Default Re: Stability of a rotating asteroid housing a space station

    Quote Originally Posted by sharpiefan View Post
    A good reason to survey asteroids, isn't it? I'd start with the bigger NEOs, and work out into the Belt.
    For sure. Bazillions of acres of easily mined-and-moved everything. Caveat: if you're in orbit.

    Andy
    "We were schooner-rigged and rakish, with a long and lissome hull ..."

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    Default Re: Stability of a rotating asteroid housing a space station

    Quote Originally Posted by AndyG View Post
    For sure. Bazillions of acres of easily mined-and-moved everything. Caveat: if you're in orbit.

    Andy
    As Robert A. Heinlein said, “Get to low-Earth orbit and you’re halfway to anywhere in the solar system."
    Click for larger image
    Last edited by sharpiefan; 02-09-2019 at 06:24 PM.

    Hope the voyage is a long one.
    May there be many a summer morning when,
    with what pleasure, what joy,
    you come into harbors seen for the first time...

    Ithaka, by Cavafy
    (Keeley - Sherrard translation)

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