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  1. Standard member pawnpaw
    Please Pay Attention
    11 Oct '15 05:47 / 1 edit
    NASA is planning to bring parts of an asteroid closer to earth at about 2020, and park it in an orbit around our moon to investigate, explore and mine.
    Depending on the size of it, won't it have an effect on the earth/moon relationship of balance?

    https://www.nasa.gov/content/what-is-nasa-s-asteroid-redirect-mission

    Maybe by that time they will know what's the limit on that.
  2. Standard member DeepThought
    Losing the Thread
    11 Oct '15 06:08
    Originally posted by pawnpaw
    NASA is planning to bring parts of an asteroid closer to earth at about 2020, and park it in an orbit around our moon.
    Depending on the size of it, won't it have an effect on the earth/moon relationship of balance?

    https://www.nasa.gov/content/what-is-nasa-s-asteroid-redirect-mission

    Maybe by that time they will know what's the limit on that.
    Yes, but if I jump up and down it affects the earth moon orbit. The asteroid could be huge and not have a measurable effect on the earth moon "balance". To give an idea, assume the asteroid has about the same density as the earth and weighs one billionth the mass (so it won't change the earth moon orbit by much), we get to something about one thousandth of the radius of the earth. That's a 6 km radius. I'd be surprised if they were considering playing with something with a radius more than about six metres. So no, don't worry, the moon won't be flung out of earth orbit a la Space 1999.
  3. 11 Oct '15 18:06
    Originally posted by DeepThought
    I'd be surprised if they were considering playing with something with a radius more than about six metres.
    Moving anything sizeable enough to affect the earth / moon 'balance' would take far more energy than we can currently pack on a spacecraft.
  4. 12 Oct '15 14:33
    Ok lets assume that NASA is being ambitious and is going to move a 100m radius asteroid,
    and that the one they pick is mostly iron at ~8000kg/m3.

    That gives us an asteroid massing in at ~33.51 Million metric tonnes. [~33.51E9 kg]

    The Earth mass is roughly ~5.972E21 metric tonnes. [~5.972E24 kg]
    The Lunar mass is roughly ~7.348E19 metric tonnes. [~7.348E22 kg]

    This means that our asteroid is ~5.611E-15th of the mass of the Earth or ~4.560E-13th of the
    mass of the Moon.

    The Earth Moon separation is ~384,400km [and we assume remains constant]
    If we make the Moon ~4.56E11% heavier then the centre of mass will move by ~~2 micro-Meters.

    I don't think this is an issue.
  5. Standard member pawnpaw
    Please Pay Attention
    12 Oct '15 18:05
    Originally posted by googlefudge
    Ok lets assume that NASA is being ambitious and is going to move a 100m radius asteroid,
    and that the one they pick is mostly iron at ~8000kg/m3.

    That gives us an asteroid massing in at ~33.51 Million metric tonnes. [~33.51E9 kg]

    The Earth mass is roughly ~5.972E21 metric tonnes. [~5.972E24 kg]
    The Lunar mass is roughly ~7.348E19 metric tonnes. ...[text shortened]... e centre of mass will move by ~~2 [b]micro-
    Meters.

    I don't think this is an issue.[/b]
    Thanks for the reassurance. With experts like you guys around, we don't have to worry about similar stuff anymore.
  6. 12 Oct '15 19:43
    Originally posted by pawnpaw
    Thanks for the reassurance. With experts like you guys around, we don't have to worry about similar stuff anymore.
    The problem is that a little bit of critical thinking should have told you that this was a non-issue.

    Both the Earth and the Moon regularly get hit by small asteroids, and even more regularly there
    are small asteroids that pass close by. [remember the asteroid that hit Russia not that long ago,
    that kind of thing happens quite frequently, just not over populated areas]

    If these asteroids caused a significant effect to the Earth Moon system it should be obvious and
    a news story whenever it happened...

    "Today on the news at ten... Tide tables around the world are being updated again to account for the
    the small asteroid that just passed through the Moons orbit, fishermen and other sea users are being
    urged to download the updated charts today..."

    As this obviously doesn't happen, it should be clear that this isn't an issue, without needing to do
    any maths.

    Being 'an expert' is not the issue, pre-gcse science/maths is more than enough to demonstrate that
    this isn't a problem.
  7. 12 Oct '15 21:01
    Originally posted by pawnpaw
    Thanks for the reassurance. With experts like you guys around, we don't have to worry about similar stuff anymore.
    NASA has plenty of experts, and to a large extent you don't have to worry too much about what they get up to. Its politicians you have to watch as most of them are not expert at what they are tasked with doing.
  8. Standard member DeepThought
    Losing the Thread
    13 Oct '15 11:54
    Originally posted by twhitehead
    NASA has plenty of experts, and to a large extent you don't have to worry too much about what they get up to. Its politicians you have to watch as most of them are not expert at what they are tasked with doing.
    Such as finding their arses with their elbows.
  9. Standard member sonhouse
    Fast and Curious
    13 Oct '15 12:38
    Originally posted by googlefudge
    The problem is that a little bit of critical thinking should have told you that this was a non-issue.

    Both the Earth and the Moon regularly get hit by small asteroids, and even more regularly there
    are small asteroids that pass close by. [remember the asteroid that hit Russia not that long ago,
    that kind of thing happens quite frequently, just not ...[text shortened]... he issue, pre-gcse science/maths is more than enough to demonstrate that
    this isn't a problem.
    The Earth gets hit with thousands of tons of micrometerite dust every day and that has gone on for 4 billion odd years. So say 10,000 tons, say 40,000 Kg a day comes out to about 5 E 16 kg total or thereabouts. Earth masses about 6 E24 Kg so the amount of dust that has hit Earth during its entire lifetime is about 10 billionths of Earth mass. I imagine all the asteroids and such that ever hit Earth wouldn't have massed much more than that either.