Posted on 05/02/2005 4:06:49 PM PDT by KevinDavis
SANDUSKY, Ohio - Scientists working with a synthetic material 100-times thinner than a piece of paper are testing their theory that the sun can power interplanetary spacecraft. They believe that streams of solar energy particles called photons can push a giant, reflecting sail through space the way wind pushes sailboats across water.
(Excerpt) Read more at story.news.yahoo.com ...
Actually on fore and aft sailboats, the wind pulls it using the same effect that causes an aircraft wing to create lift.
I have been in that vacuum chamber at Plum Brook. It is HUGH! And they have some other nice facilities there, too. Just hope they don't shut it down.
The solar sail is actually a pretty old idea. I've read about it most of my life.
Still sailing a space craft is not nearly as impressive as using oars to row it.....
A better idea might be to build mag-lev like rails, that
propel a vehicle alongs the path of the rail, accelerating
the craft to very fast speeds...(like the rail gun, they
are supposedly developing)...get the light from the sun,
and generate high electrical energy, aim, and fire...
A 50 mile rail gun could get the vehicle moving very fast.
..
They could get water from the moon, split it using hydrolysis
to get H2, and O2, ship it up to a vehicle and use the
old hydrogen oxygen reaction to get propulsion that way...
Any other great ideas outthere??
P.S. I've heard about space sails since 5th grade...
45 years ago or so....surprised they haven't tested that
concept in space yet....
Long before that, it appeared in magazines in the 50's
Sho 'nuff: I read (and still have) lots of them.
They have the same problem now that they did then: No way to steer.
A sail boat steers, because the keel resists going sideways through the water, forcing the boat to tack.
In space, it doesn't matter how much you angle the sail, the photonic vector is still radial to the sun, ignoring gravity of nearby bodies.
IOW, you can only run before the wind; you can't tack, no matter how many steering oars & rigging lines you have.
But remember, the imparted thrust also depends on the direction the photons are reflected, thus, by angling the sail, you can steer it somewhat! Of course, when you do this, you lose some efficiency because of the decrease in "frontal area" which is impacted by the photon stream. However, there are designs for parabolic sails with sub-mirrors that allow steering plus nearly the full use of the photon stream.
This is true, it is only good for outbound ships, discounting any gravity assist.
My thinking is a combination of black/white "sails" set up at different angles to redirect/catch/reflect photons and
emit heat energy to direct the craft.
Granted, by comparison an oil tanker would be as nimble as an acrobatic plane...
Right, but that is a small, though long term input...same as the thrust itself is.
That is fine for long range course corrections etc, but useless for what one thinks of as 'steering' in the way attitude thrusters coupled with main thrusters control, say, the shuttle during a docking manuever.
Also, by angling the sail, the effective area of it is reduced, thus also reducing the overall thrust available, complicating the calculations for orbital changes.
Those early pulp stories that got me started on the thread had these things pretty much acting like sailing ships in space, "tacking before the solar wind" kind of thing.
As for the sail, what would it take to build a 'toy'? (Scale model actually), lift it, boost it, and deploy it to see if it would really go?
If water boils/sublimates at a low temperature in a vacumn, why not just use steam? Merely opening and closing the orifice at the end of the tank should do it.
Sounds good, until you realize that the sublimation, boiling actually, removes heat from the system, so in short order, you'd have a chunk of ice that no longer spewed steam. So you'd have to inject heat. Essentially youd have a steam jet engine, which is actually possible and has been considered for space missions before.
I don't know how they determined the H2 content, but CH4 (methane), is, in terms of atoms (and atomic weight, iirc) more hydrogen than water...
(Feel free to correct me if I am wrong, the Periodic table in my head has grown smudged and fuzzy over the years.)
I suppose either could accumulate, given the right conditions or as a result of comet fragment impacts.
Oh, certainly. Anything that can be vaporized can do. I read a story once in which the working "fluid" was zinc!
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