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Station Weight



I believe I remember that it was mentioned a couple of days ago that the
space station's orbit is altered a bit when the shuttle docks with it
because the MASS of the shuttle is added to that of the ISS.  I'm left to
assume that you're saying that the weight of an object in orbit has some
effect on the orbital speed.

I have wondered about this.  From high school physics I thought I remembered
that the weight of a satellite didn't matter a whit.  Only the altitude
above the earth had any bearing on the orbital speed.  So I decided to do
some digging.

>From a physics book I found a formula that tells you how fast an object in
orbit must go in order to stay up.  Too fast and it flies away; too slow and
it falls back to earth.

I can't type out the formula as it appears in the physics book, but I'll
describe it.  First you take the gravitational constant and multiply it by
the mass of the earth.  This figure always comes out to be 4.002 X 10 to the
14th power.  This figure goes on the top of a fraction bar.

Beneath the fraction bar you have the orbital radius, which is the radius of
the earth plus the altitude of the satellite.  Once that fraction is worked
out to a whole number, you take the square root of it.  That gives you the
velocity of the satellite.  That's how fast if must go to maintain orbit.

Perhaps the weight of the satellite doesn't appear in this formula because
it's negligible compared to the mass of the earth.  My question is this:
Does the weight of the shuttle really make any difference when it becomes
part of the space station?

Your orbital mechanics lessons are appreciated.

73, James Alderman, KF5WT
Dallas, TX  USA

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