Japanese Deploy Solar Sail

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.""

Comments

Stellar Pong?

[infonick]

"...it is the only technology now in existence that can one day take us to the stars." Well, unless the Japanese can automate retraction of the sails, it wont reach any stars. While it's powered by solar wind, it will slow down and reverse as it gets farther from the original star and closer to the destination star.

Re:Stellar Pong?

[Anonymous Coward]

I call baloney. Doesn't a solar sail work because of it's high reflectivity? Isn't that high reflectivity only on one side of the sail?

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?

[JVert]

WHAT?
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:Stellar Pong?

[Famatra]

"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:Wrong

[gilroy]

Blockquoth the poster:

Orion can take us to the stars, and it can be done with today's technology, not something that's just starting to enter the very earliest test phases.

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:Ironically

[mcrbids]

Ironically, this technology can take us to 'the stars' but not toward our own.

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 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 .5 C, it'd take thousands to millions of years to get anywhere. But, at relativistic speeds, it'd still take thousands of years, but to the crew on board, it'd be like mere hundreds or even tens of years.

You need power to get you there in less than hundreds of years - thus the RamJet.