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The Flight of the Solar Sail
N3wsByt3 writes "After months of uncertainty, the final verdict has fallen: The Planetary Society has reveiled that it will launch its Cosmos 1 on June 21. Cosmos 1 will be the first non-governmental spaceship that makes use of solar sails as main propulsion mechanism - it is pushed along by light particles from the Sun, instead of bringing its fuel along for the ride - which makes this a unique experiment in more then one way." This was supposed to have happened already, so here's hoping things get off the ground this time.
"reveiled:" is that like the opposite of "unveiled?" So, are you saying that they have tried to cover up the news? And if so, then how are we finding out? Or is it from the French "reveil:" the awakening. Did they wake up to the news? Is that why they tried to cover it up?
So confused.
If you open yourself to the foo, You and foo become one.
all the governmental solar sail spacecraft? WTF?
Honestly the idea that because it doesn't carry fuel makes it easy to 'travel to the stars' is kinda stupid. For one thing, almost by definition you can't travel towards a star on this thing because as you approach it, it will start to slow down, and eventually stop.
The idea of using the suns energy is good, but maybe they should find a way to harness that energy so one could move the direction one pleases.
"A man is but the product of his thoughts what he thinks, he becomes." -Mahatma Gandhi
planetary.org is the Planetary Society, the people who are, you know, launching the sail. As the sail the Society is launching will be the first solar sail, you won't find any government solar sails.
As the solar sail travels the solar system, it would slowly accellerate, reaching approximately 0.1c exiting the system, according to Carl Sagan's wife, who is funding the project.
You could use a solar sail to go from Earth to Mercury if you wanted.
Angle it so that thrust is opposite the orbital motion of the earth. You slow down relative to the sun. You fall to a lower orbit. Nifty, huh?
If you're really in a hurry to slow down you detach a reflector, let it fly in front of you, and have a planet-based launching laser fire at the reflector, bounce back to you and slow you down.
so apparantly we have the technology to propel objects via sunlight... but we still cant make our cars to utilize a resource besides gasoline ( with a little hydrogen somestimes)?
This particular sail is not expected to escape from earth. From the article: " It is possible that by this time the spacecraft will have risen to a high enough orbit that it will remain there, forever orbiting the Earth. It is more likely, however, that the orbit will slowly decay, and Cosmos 1 will end its days as a fireball in the Earth's atmosphere."
That's because the material of the sails is not very resistant and will break after about a month. I suppose that a stronger sail could eventually reach the edge of the solar system, but someone else will have to fill us in on how long that would take.
A solar sail could, theoretically, pass the Voyagers in less than a week. That's the advantage of having continuous thrust along the way, rather than one impulse at the start and then coasting as the Voyagers did.
The Voyagers are now at a distance of about 13 light-hours from the sun. A thin and lightweight solar sail would quickly accelerate to almost the speed of light, so it's possible to cover that distance in a few days at most.
The problem with the parent's post is the sail itself. Our solar system is a rocky and dangerous space, and so far, we have no idea what the area outside of it is like either.
The sail would quickly break apart as it gets struck by all kinds of space debris, some left by us, others by more natural occurances. Thus, for an effective craft, multiple sails would be kept on board, being deployed stratigically when the previous sails are no longer providing maximal thrust, and when the coast is clear.
Next, between those times when the sails are not up, the ship will probably want to keep thrust, so it will have to carry onboard some propellant to keep its thrust up during the times it is without sails. Thus, the ship will lose a significant portion of weight during its travel.
Lastly, unless we align everything like we did with the Voyager launches, gravity will not be so forth coming for this space craft. This will probably mean multiple near-sun passes to build up the speed nessicary to exit the solar system and continue on to the next star. This means some clever routing by computer simulations, along with a computer figuring when to discard and open new sails along the way.
Not only will all of this cost a lot, it will likely make it take much longer to get out of the solar system. Lucky for us, as we can pile on the goodies like cameras, radio antenna, and do some exploration as it passes through the planets building up gravitational accelleration.
"Victory means exit strategy, and it's important for the President to explain to us what the exit strategy is." G.W.Bush
first of all, there's no such thing as a perfect reflector, so there's always going to be be some loss. but there's a grand tradition of frictionless planes and other such things in these though experiments, so we'll give you that.
second, unless you have perfectly coherent light (super laser), you'll have dissipation of the beam. we'll spot that, too (see above).
once those have been taken care of, the dealbreaker is going to be that the reflected photons are red-shifted when they bounce off each sail.
the energy of a photon (E) is equal to Plank's constant (h) times the frequency (f).
the increase in kinetic energy of the sail is conserved conserved due to a lower frequency of the reflected photon.
Fermat's other theorem: "I have a simple proof, but I can't write it down as I fear it's a DMCA violation to discuss it"