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View Diary: Scientific American Gives Details on the Russian Meteor (277 comments)

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  •  Very little gravity in an object that size. (2+ / 0-)
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    pistolSO, Aunt Pat

    You'd need a specially-designed accelerometer to detect gravitational force that small.

    Pour yourself into the future.

    by Troubadour on Sat Feb 16, 2013 at 04:03:57 PM PST

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    •  even then (1+ / 0-)
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      Troubadour

      wouldn't the satellites still be in free fall, and thus unable to detect gravity?

      the purpose of the second amendment is to promote a well-regulated militia, in the same sense that the purpose of the first amendment is to promote a well-informed electorate.

      by happymisanthropy on Sun Feb 17, 2013 at 09:59:40 AM PST

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      •  Freefall = gravitational acceleration. (0+ / 0-)

        In orbit, acceleration takes the form of continuous changes of direction bending a path into a circle or ellipse.  If you introduce another gravity field via a significant mass, that changes the acceleration and thus alters the path.  A big asteroid would only alter a nearby satellite's orbit slightly, but it would be detectable.

        Pour yourself into the future.

        by Troubadour on Sun Feb 17, 2013 at 11:12:31 AM PST

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        •  we could detect its changed orbit (0+ / 0-)

          but an object in freefall can't feel the gravity acting on it, even if it has a very nice accelerometer.

          the purpose of the second amendment is to promote a well-regulated militia, in the same sense that the purpose of the first amendment is to promote a well-informed electorate.

          by happymisanthropy on Sun Feb 17, 2013 at 01:10:21 PM PST

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          •  The closer a mass gets (0+ / 0-)

            the stronger its gravitational force, which increases the acceleration associated with it.  Increasing acceleration is not freefall - the force is changing, so it would be detectable.  But it would have to be a substantial mass, and it would have to come damn close.

            Pour yourself into the future.

            by Troubadour on Sun Feb 17, 2013 at 02:33:10 PM PST

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            •  I don't think so (1+ / 0-)
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              Troubadour

              if you're inside an elevator in freefall, there's no way to tell the difference between accelerating at 1.0 G at the earth's surface, or 0.01 G in the outer solar system, or 10.0 G through the clouds of Saturn.  All you know is there's nothing holding you up.  And if the weight inside an accelerometer is accelerating at the same rate as the frame of the accelerometer, it will read zero.

              the purpose of the second amendment is to promote a well-regulated militia, in the same sense that the purpose of the first amendment is to promote a well-informed electorate.

              by happymisanthropy on Sun Feb 17, 2013 at 02:54:55 PM PST

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              •  Hmm, you're right. (0+ / 0-)

                I misinterpreted the scenario.  And I also forgot how they do gravity-mapping - by comparing the positions between two spacecraft.

                Pour yourself into the future.

                by Troubadour on Sun Feb 17, 2013 at 03:15:59 PM PST

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