Japanese Deploy Solar Sail 433
Chuck1318 writes "The Japanese ISAS (Institute of Space and Astronautical Science) announced the launch and deployment of the first ever large-scale solar sail. In the news release they state "Because it carries no fuel and keeps accelerating over almost unlimited distances, it is the only technology now in existence that can one day take us to the stars.""
Stellar Pong? (Score:4, Insightful)
Re:Stellar Pong? (Score:5, Insightful)
And what's so difficult about retracting the sail? The force on the sail at any given time is so miniscule it's trivial to retract them (as opposed to, say, when you have intense winds blowing on your sailboat's sail).
Re:Stellar Pong? (Score:2, Insightful)
Not so fast... (Score:1, Insightful)
This may be true, but it'll take another technology to take you there safely: brakes.
This whole "keeps accelerating" schtick concerns me from a self-preservation point of view...
Re:Physics (Score:3, Insightful)
I'm no scientist, but wouldn't the thrust follow the same inverse-square law as radiant light?
To make best use of a solar sail, it would probably make sense to use a conventional rocket to establish a highly eccentric (parabolic) orbit around the sun and then pop the sail open after perihelion where the sail would contribute the most energy to the orbit.
I think aiming the spacecraft (on the outbound journey) would be the hardest part.
Re:Wrong (Score:5, Insightful)
Because Orion needs to carry its fuel, its period of acceleration is necessarily limited. If you count Orion as a star-faring technology, then you need to count chemical rockets, too... Just ask Pioneer 10.
Re:Stellar Pong? (Score:5, Insightful)
no.
try sailing upwind in a circular boat.
Regardless of how late it is, you should have caught this one before you hit 'post'... or am I about to Have A Nice Day?
Re:Ironically (Score:5, Insightful)
And, why not?
Sailing ships have sailed "upwind" for many centuries.
In outer space, you are either in orbit, or falling directly towards the nearest large body. A solar sail can be used to slow down or accellerate lateral speed simply by rotating it 45 degrees.
A simple google search turned up this [nasa.gov] in case you are curious.
Although they are right, in that solar sails do accelerate the entire trip and carry no fuel, I don't think that sails are "the way to go" unless we're talking about a ten thousand year multi-generational ship.
I consider the Bussard RamJet the "only way to fly". It carries no fuel, but is powered by carving a planet-sized swath out of the ambient hydrogen atoms out of interstellar space and fusing them.
With interstellar distances, the real issue is: how quickly can you get to relativistic speeds? Because, at
You need power to get you there in less than hundreds of years - thus the RamJet.
Re:Physics (Score:2, Insightful)
Re:Stellar Pong? (Score:4, Insightful)
"Once there, you jettison the sale, or use it to fly around the star system."
;).
Perhaps you'd like to explain how jettisoning a solar sail has enough force to slow down the craft.
That sail would have to be pretty massive, like the mass of a planet, in order to counteract years of acceleration so you could push it away from yourself to slow down
That is the problem with getting somewhere in space. To get there the fastest you have to accelerate continually there till the 1/2 way point, turn the ship around around and use an equal force / fuel to decelerate. Reminds me of a scene in Battle Star Galatica Crew Member: "Sir we've ran out of fuel", Admiral "Come to a complete stop", The right reply: "But Sir, I said we ran out of fuel".
Re:Good to see (Score:2, Insightful)
Re:calculations from NASA (Score:2, Insightful)
These solar sails are pretty useless.
That's because they weren't designed to be useful--they were designed to gather data for the purpose of eventually building useful ones. This particular article is light on details, but the report I saw on the news here had someone from JAXA explicitly saying they are in a preliminary data-collection stage.
dumb shmuck... (Score:3, Insightful)
OF COURSE it's not shining laser light into the sails from the ship itself, like a sailboat with a fan on it, you unbelievable moron. And as for getting "worse and worse with aim", you DO NOT TRY AND POINT THE LASER AT THE FAST-MOVING AND LIGHT-YEARS-DISTANT SPACESHIP, AND DO COURSE CORRECTIONS BY MOVING THE LASER, you just keep the laser pointed at the destination, and do course correction at the ship.
The problem here is not so much that you completely misunderstood the whole concept, it's that you so vastly overestimate your intelligence and knowledge that you didn't recognize your stunning incapacity to evaluate this suggestion.
So let's review:
1- you're not as bright as you think
2- other people are brighter than you think
3- other people have often evaluated things a lot more thoroughly than you are capable of doing in 30 seconds
4- if you don't understand something, it's more likely your own defect than a problem with the expressed idea
5- sit down and shut the fuck up, you arrogant ignoramus
Now that that's out of the way, there certainly are practical issues with this method of space travel. It's just that they have absolutely nothing to do with what you thought they were.
Re:Stellar Pong? (Score:3, Insightful)
If you could somehow cause the energy absorbed by the leading black surface of the sail to be emitted out the rear surface as photons, then you would have something practical.
The parent's point was that as the sail gets farther away from Sol, the energy from other, nearer stars (the destination) would "push" on the leading surface and this force would eventually be greater than the force on the rear surface, causing the sail to be blown back towards home.Think of two kids and a little sail boat in a small tub of water. Each kid is trying to blow the boat to the opposite side. As the boat nears one side, the "defender" has a clear advantage. The boat will ping-pong back and forth, never reaching either side.
Re:Not the only way t o the stars. (Score:3, Insightful)