From: Chuck Kuecker (ckuecker@ckent.org)
Date: Thu Jul 03 2003 - 11:42:05 MDT
As long as you call the sail a "heat engine", as Mr. Gold is doing, I guess
you can call a sailboat's sail a heat engine, too. There's a big difference
between converting one form of momentum into another and converting heat
energy into momentum. Sure, the sail will heat up, proportionally to how
much energy it absorbs, but it is in no way converting heat to momentum,
unless you want to consider the effect of the momentum of the radiated
energy off the "heated" sail.
I don't see why a solar sail would get any hotter from sunlight than any
other object of similar albedo, either.
He talks of the Crookes radiometer - a device that has been shown to
operate because of increased local gas pressure due to the heating of the
blackened sides of the vanes. This gadget won't spin at all in a good vacuum.
Sounds like Mr. Gold just does not want anyone spending any of his tax
money (or investments) on solar sails...
Chuck Kuecker
At 18:20 07/03/2003 +0200, you wrote:
>'The solar sail and the mirror'
>by Thomas Gold (Center for Radiophysics and Space Research, Cornell
>University)
>-3 pages, no figures-
>
>http://arxiv.org/abs/physics/0306050
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