> Date: Tue, 1 Dec 2009 11:20:45 +1100
> To: [email protected]; [email protected]
> From: [email protected]
> CC: [email protected]
> Subject: [amsat-bb] Re: Boost To higher Orbits?
>
> At 11:17 PM 11/30/2009, Bob McGwier wrote:
>
> >p=hk where p is momentum, k is Planck's constant, and k is an integer.
> >
> >So when a photon is captured or reflects/scatters, it transfers
> >momentum. This equation is used to determine how much momentum is being
> >transferred.
> >
So, the discussion is about the fundamentally different ways to cause force to
be applied to the satellite.
Most of the time we operate by Newton's 3rd law, throwing parts of the
satellite out one end, with the knowledge that doing so will push the remaining
parts of the bird in the other direction. We call them rockets.
Conservation of Momentum is just another aspect of Newton's 3rd law. Any time
you cause something with mass to move differently, there's always a got to be a
balancing force. Bouncing photons off a sail is only different from a rocket
in that the rocket is shedding parts of itself as it works, while the photons
are external. And a they are lot lighter (no pun intended), so it takes a
whole lot of them to have the same effect, making it less than practical.
Looking at the other laws of physics we have Bernoulli's principle, where the
increased velocity of a fluid over a curved surface causes a pressure drop
which can push the surface in the direction of the lower pressure. We call
them propellers and lanteen sails. Is there any way to use this principle with
the solar wind? I think that was answered as a theoretical yes, but a
practical no.
So what remains? What about magnetic or electrostatic forces? Friction?
Anything else I missed?
It would sure be nice to be able to propel a satellite without tossing bits of
it overboard.
Greg KO6TH
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