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Solar Sailing and Physics
Roland Piquepaille writes "In this article, the New Scientist writes that the next generation of spacecraft might be propelled with the help of the sun. "Both NASA and the European Space Agency are developing solar sails and, although never tested, the concept is quite simple. A solar sail is essentially a giant mirror that reflects photons of sunlight back in the direction they came from." But Thomas Gold from Cornell University in New York says the proponents of solar sailing have forgotten about thermodynamics, the branch of physics governing heat transfer." And this is where it's becoming interesting. Gold's paper, "The solar sail and the mirror," states that "either Carnot's accepted rule is in error, or the solar sail proposal will not work at all." So, as this illustration from New Scientist shows, the real question is: "Can it really sail away?" We'll know it in September when the first tests are done. In the mean time, read this summary for more details and read the original stories for far more information."
*picks up fire-proof boat*
Sun, here I come!
Of course it runs NetBSD. BTC: 1NT7QvbetmANwaMzhpVL6
"We obey the laws of thermodynamics in this house young lady!" -Homer Simpson
The Solar Sail and the Mirror says:
"If this was a perfect mirror, the two temperatures will be the same"
This ignores the frequency shift due to the moving mirror. Proof falls down. Thermodynamics and conservation of momentum both still hold.
Physics correct! News at 10!
Yawn.
NO ID: BEING FREE MEANS NOT HAVING TO PROVE IT
Yes, of course.
Here is a clue: Gold is an idiot.
Just because people on slashdot are calling him by his last name doesn't mean he knows what he is talking about.
NO ID: BEING FREE MEANS NOT HAVING TO PROVE IT
A solar sail is essentially a giant mirror that reflects photons of sunlight back in the direction they came from
Great, so in a few hundred years the granola crunchers will start complaining that we're causing Solar Heating.
Trolling is a art,
the second law of thermodynamics is only a statistical law
I'm not a physicist, but I thought the first two laws of thermodynamics were:
1. You do not talk about thermodynamics.
2. You do not talk about thermodynamics.
Maybe I'm getting confused with something else.
Suck figs.
>We still need someting like Prometheus in order get around and about in places where the sun doesn't shine brightly.
OUCH...my doctor usually just uses an index finger!
Just another day in Paradise
How does your doctor travel to Lancre by unsing his index finger???
The illegal we do immediately. The unconstitutional takes a little longer.
--Henry Kissinger
Q: If the solar sail works by using the sun's photons to push you away, then how do you get home again? A: Come back at night.
Try s/Lancre/Uranus...
Stop by my site where I write about ERP systems & more
A friend of mine came up with some additional bits of the theory of conservation of momentum a while back.
See, we were wondering what happens when, say, a car hits a snow bank. Car slows to a stop. Snow bank is, broadly speaking, immobile.
So he decided that it must be that the momentum was now stored up in the snow bank, as *potental* *momentum*. Unfortunately, before we could figure out how to harness this (or indeed where it went once the snow had melted), the pub closed.
-fred
Sign #11 of Slashdot overdose: You see the phrase 'moderate Republican' and you wonder if that would be a +1 or a -1.