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View Full Version : Discussion: Solar Sail on Exhibit in New York



Fraser
2003-Jul-31, 10:33 PM
SUMMARY: A full-sized replica of a Cosmos 1 solar sail is now on display at the Rockefeller Center "Centennial of Flight" exhibit in New York City. The 14.3 metre blade is made of a silvery Mylar-like material and joins several other exhibits at the show. If all goes well, the real solar sail will be launched on board a refurbished Russian ICBM some time this fall. The sail will be on display until August 18, 2003.


Comments or questions about this story? Feel free to share your thoughts.

imported_James
2003-Aug-05, 10:19 PM
I would like to invite anyone who believes the solar sail will work to tell us how a massless photon can be made to impart momentum to the light sail.

May the future be kind to you
Boycott SPAM

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Fraser
2003-Aug-05, 11:27 PM
Solar sails have been demonstrated to work in the laboratory. This is a fairly well understood principle.

Here's a webpage that explains the principle.
http://www.ugcs.caltech.edu/~diedrich/sola...ntro/intro.html (http://www.ugcs.caltech.edu/~diedrich/solarsails/intro/intro.html)

imported_James
2003-Aug-11, 12:43 AM
Regarding <http://www.ugcs.caltech.edu/~diedrich/solarsails/intro/intro.html>: The arguments are fallacious.

Maxwell;
Photons (including light) are massless and as such are incapable of imparting a change of momentum (a function of mass) by impact (reflection). The only way a photon can effect mass is by being converted into the energy necessary to shift an electron to a higher energy state. There is no evidence that there is a consistent vector so any acceleration from this source could be in any direction. The other effect, emitting a photon when an electron goes to a lower energy state, has never been considered a source of acceleration. If this were the case, there would be some evidence of high powered lasers being pushed while in operation.

Einstein;
The author equates energy with force without justification. The means of applying the energy is missing.

Conclusion;
It would be nice if it works, but I have yet to see any theory that supports it. I support the experiment of deploying a light sail as it will put this whole topic to rest, one way or the other. I do not expect to be surprised. I was really disappointed when the first attempt was aborted (launch failure).

May the future be kind to you
Boycott SPAM

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Planetwatcher
2003-Aug-11, 06:29 AM
I&#39;m thinking the sail will work, but not as well as predicted, at least not at first.
A solar wind sail is the direction I believe we will likely pursue after the limitations of the light sail are publicly declared.

Even then the sail will have to be enormus, and the ship tiny with a small crew.

Guest
2004-Mar-07, 06:46 PM
James...regarding your quote:
[Conclusion;
It would be nice if it works, but I have yet to see any theory that supports it. I support the experiment of deploying a light sail as it will put this whole topic to rest, one way or the other. I do not expect to be surprised. I was really disappointed when the first attempt was aborted (launch failure).]

I have a radiometer which I bought at the 1963 Seattle World&#39;s Fair(Space Needle that Jessica Alba stood on in &#39;Dark Angel&#39;). It&#39;s an evacuated glass flask with little fins inside balanced on a needle. The 4 fins are painted white on one side and black on the other side. Put it in the sunlight and it spins like crazy. Use a flashlight, and it spins. Direct light at it from angles other than perpendicular to the fins and the rate of spinning changes proportionally with the angle of incidence of light. So, the "effect" is directional.

The solar sail will be tested in a better vacuum that exists in my little radiometer, so it will probably perform better.

This is past the point of theory, there is an observable effect. Perhaps your doubts should not be directed so much at "will it work" but "how does it work". Also, considering how time consuming and costly it is for any private organization such as The Planetary Society to attempt projects such as this, I doubt that they would even begin such an attempt unless they were really, really sure of some good result. And as a member, I am especially interested in their success.

-Tom B)

Tom2Mars
2004-Mar-07, 06:57 PM
That was me just now, forgot to log in...Tom :o