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Japanese Deploy Solar Sail

timothy posted more than 9 years ago | from the ix-as-an-archipeligo dept.

Space 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.""

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Nichts, damit Sie hier sehen. Bewegen Sie bitte en (-1, Redundant)

Anonymous Coward | more than 9 years ago | (#9926829)


YAY!!!!!1111

i got a fp!!!! w00t!!!

*jumps up and down happily*

fp! (-1, Redundant)

Anonymous Coward | more than 9 years ago | (#9926831)

Yea first post bitch!

YOU FAIL IT! (-1, Offtopic)

Anonymous Coward | more than 9 years ago | (#9926868)

Yea YOU FAIL IT bitch!

base64 failure (1)

lu004202 (784823) | more than 9 years ago | (#9927037)

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Stellar Pong? (4, Insightful)

infonick (679715) | more than 9 years ago | (#9926832)

"...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? (3, Interesting)

mrchaotica (681592) | more than 9 years ago | (#9926850)

What if it's only reflective on one side?

Re:Stellar Pong? (5, Informative)

pclminion (145572) | more than 9 years ago | (#9926941)

What if it's only reflective on one side?

A perfectly non-reflective surface (i.e. a black surface) would experience half the force that a perfectly reflective surface would. In other words, a black sail will work, but only half as well as a mirrored sail would work.

This is due to conservation of momentum. If a photon is reflected, its momentum p is reversed to be -p. Thus the sail must acquire a momentum 2p to conserve momentum. Whereas if the photon is absorbed, its momentum changes from p to 0, thus the momentum of the sail must increase by p, again to preserve momentum.

The difference in kinetic energy is converted into heat. A black sail heats up. An ideal, perfectly reflective mirrored sail does not heat up at all.

Re: Stellar Tron (2)

weston (16146) | more than 9 years ago | (#9926859)

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.

No, see, that's where Jeff Bridges comes in.

Re:Stellar Pong? (5, Insightful)

Anonymous Coward | more than 9 years ago | (#9926862)

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).

Obvious Answer (4, Funny)

rf0 (159958) | more than 9 years ago | (#9926872)

Solar Anchor :)

Rus

Re:Stellar Pong? (2, Insightful)

Anonymous Coward | more than 9 years ago | (#9926883)

Well, unless the Japanese can automate retraction of the sails, it wont reach any stars
Why retract? Just release. It's not like it's going to be used again.

Re:Stellar Pong? (5, Informative)

Anonymous Coward | more than 9 years ago | (#9926885)

Actually you want to slow down when you reach the other star. Or else you miss your stop. Once there, you jettison the sale, or use it to fly around the star system.

Read "Flight of the Dragonfy"/"Rocheworld" (they are the same book) by Doctor Robert L. Forward for an informative and entertaining novel using (laser pumped) solar sails.

Re:Stellar Pong? (4, Informative)

halowolf (692775) | more than 9 years ago | (#9926994)

Also the The Mote in God's Eye [amazon.com] is a good read that has a solar sail powered craft, however a huge assortment of lasers were used to propel it up to speed, far beyond what solar energy would of provided. And its also not the focus of the book. But hey read it and find out!

There is also a sequel but I will leave that up to you as a project to find out what it is.

Re:Stellar Pong? (1)

BerntB (584621) | more than 9 years ago | (#9927011)

Read "Flight of the Dragonfy"/"Rocheworld" (they are the same book) by Doctor Robert L. Forward for an informative and entertaining novel using (laser pumped) solar sails.
That was new!

Now, I'll agree with informative -- but entertaining??

I usually describe Forward as the absolutely worst author whose books I buy in hardcover.

You must be a nerd and talking about the physics and engineering as "entertaining" -- and not any literary qualities!

(-: Reminds me of when I recommended a Farmer book to an ex girl friend. I said "this is a classic that changed the sf/f genre, well worth reading!" She thought I meant it was good and is still angry, 8-10 years later...:-)

Re:Stellar Pong? (4, Funny)

Marsala (4168) | more than 9 years ago | (#9926898)

That's why one crew member will be trained extensively in the use of tin snips in zero-gee environments.

Although that'd be a great way to freak out an alien race... Kind of like pulling a Rama on 'em.

Re:Stellar Pong? (0)

javiercero (518708) | more than 9 years ago | (#9926900)

Newsflash for you: there ain't much friction out there in Space :) so the solar sail will not slow down much. Particles may hit it, but the density is not enough to counteract the momentum the sail will gather at the beginning of the trip.

Re:Stellar Pong? (0)

Anonymous Coward | more than 9 years ago | (#9927025)

there ain't much friction out there in Space :) so the solar sail will not slow down much. Particles may hit it, but the density is not enough to counteract the momentum the sail will gather at the beginning of the trip.



Um, did you read the article, the summary, or even the comment you were replying to?"



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.



If a destination star does not emit particles of sufficient density to slow the ship, how did the ship get going in the first place?


Only if you're sending sails to super-bright stars (1, Interesting)

Anonymous Coward | more than 9 years ago | (#9926940)

If the destination star has about the same amount of solar wind (or whatever sails use; I forget what exactly) as our sun, the point where it reverses course would be about 1AU from the destination star. I'd say that's close enough to be considered "reaching another star".

Re:Stellar Pong? (0)

MidnightBrewer (97195) | more than 9 years ago | (#9926943)

Same principles apply as in Earth-based ocean sailing - if you angle the sail, you can deflect the particles, thus allowing you to use the solar wind of another star even though you are approaching it rather than leaving it.

Regardless of space or the ocean, basic principles of physics apply. Action and reaction.

Re:Stellar Pong? (4, Insightful)

JVert (578547) | more than 9 years ago | (#9927052)

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? (2, Funny)

eric76 (679787) | more than 9 years ago | (#9926944)

An interstellar yoyo?

Re:Stellar Pong? (3, Interesting)

Igmuth (146229) | more than 9 years ago | (#9926947)

And alot sooner than you would think... Once you cross the heliopause [wikipedia.org] , the solar wind is basically moot.

Re:Stellar Pong? (1, Informative)

mark-t (151149) | more than 9 years ago | (#9926954)

No. Once you have reached whatever your desired cruising velocity is, you discard the sail completely (or somehow retract it, if that is possible). The gravitational pull of the star at your destination will give you even more accelleration later on.

You use on board rockets to help steer as you draw close to your destination.

About Time (-1, Redundant)

Anonymous Coward | more than 9 years ago | (#9926833)

someone finally did this. Nasa.. are you listening?
Oh, first post

until Godzilla trashes it chasing mothra (-1, Redundant)

Anonymous Coward | more than 9 years ago | (#9926837)

fp

Whatever happened to Big1 (1, Funny)

Hido (655301) | more than 9 years ago | (#9926838)

Does this mean that plans for taking the flying steam-powered train to the stars is cancelled?

Re:Whatever happened to Big1 (0)

Anonymous Coward | more than 9 years ago | (#9926852)

They can't cancel that, I still have my ticket!

Troll? (0, Offtopic)

rsilvergun (571051) | more than 9 years ago | (#9926983)

This is a reference to Galaxy Express 999. It's a joke near as I can tell. Not a fair mod in my eyes

Ironically (3, Funny)

chancycat (104884) | more than 9 years ago | (#9926844)

Ironically, this technology can take us to 'the stars' but not toward our own. Better not change your mind and want to turn around less than half-way to Alpha Proxima...

Re:Ironically (2, Funny)

StarHeart (27290) | more than 9 years ago | (#9926867)

There is probably some engineering trick to work around this. It might be possible to use mirrors to shine on the opposite side of the sail. Almost surely wouldn't be as fast, but seems like it would be doable.

Re:Ironically (1)

cliffy2000 (185461) | more than 9 years ago | (#9926904)

And why don't we just use a fan to move a sailboat?
(Hint: think conservation of energy.)

Re:Ironically (0)

Anonymous Coward | more than 9 years ago | (#9926925)

Actually, I remember some scifi author worked out the details of how to do it. I can't remember how it worked, though.

Re:Ironically (0)

Anonymous Coward | more than 9 years ago | (#9926932)

Forget the sail. You can move like a hovercraft does by pushing air.
(Yes I know what you meant... just being a slashbot.)

Here's how it works. (0)

Anonymous Coward | more than 9 years ago | (#9926975)

What you need to do is let loose a set of mirrors in front of the ship -- those mirrors will be pushed forwards by the lasers, and then reflect the light back to slow down the ship.

Re:Ironically (2, Interesting)

Anonymous Coward | more than 9 years ago | (#9926978)

And why don't we just use a fan to move a sailboat? (Hint: think conservation of energy.)
You might be joking, but my dad used to do this all the time when he'd take us sailing if the wind would die down and we were all still out on the lake. He had a big gasoline generator and a 36-inch fan. Worked fine; moved us right along. (True, by "gasoline generator" I mean "all of us kids" and by "36-inch fan" I mean "enough oars for all of us," but, still, it worked just fine.)

Re:Ironically (1)

tufflove (580300) | more than 9 years ago | (#9926881)

Why would you want to go to the sun. You'll just die. And as previously stated, surely there is a way to retract the sail, or use reversable slats so you can control the amount of pressure or turn them perpindicular to the star, etc..... Sort of like interstellar tacking. Still, it would take an awful long time to get to any nearby stars, much less any that may support some kind of planet which would be relevant to our species.

Re:Ironically (0)

Anonymous Coward | more than 9 years ago | (#9926899)

Why would you want to go to the sun. You'll just die.
Shhh! You're not supposed to say that until AFTER the solar cruise ship is full of passengers!

Re:Ironically (1)

tufflove (580300) | more than 9 years ago | (#9926976)

Oh yeah......SHIT!!!!

Re:Ironically (5, Funny)

andreMA (643885) | more than 9 years ago | (#9926946)

Why would you want to go to the sun. You'll just die.
That, of course, is why you go at night!

Going to Sol (2, Informative)

anactofgod (68756) | more than 9 years ago | (#9926920)

You just have to tack into the solar wind. *grynn*

You heard it hear first -- America's Cup 2200.

---anactofgod---

Re:Going to Sol (2, Funny)

name773 (696972) | more than 9 years ago | (#9927048)

sounds kind of... tacky.
:)

Turning around... (1)

anactofgod (68756) | more than 9 years ago | (#9926964)

Actually, to be a bit serious, I seem to recall through clouded memory from college days long gone by that flipping the sail around was one method to decelerate the rocket on approach to the target star. In this scenario, the rocket would have maximum velocity somewhere around the mid-point between the source and destination stars.

So, unless one had other means of propulsion to facilitate a return to Sol, one would have to change one's mind a whole heck of a lot sooner than ~half-way to Alpha Proxima, otherwise it'd just be easier to just keep on truckin'.

---anactofgod---

Re:Ironically (1)

Beryllium Sphere(tm) (193358) | more than 9 years ago | (#9927012)

Turn the mirror sideways so that thrust is lateral instead of radial.

Use the lateral thrust to kill your orbital velocity.

Furl the sail.

This would work great for a trip to Mercury, actually. If you want to reverse course in between stars you need to use one of the ideas the late Bob Forward played with, e.g. a disposable mirror in front of you reflecting a launch laser to force you backwards.

Re:Ironically (1)

BerntB (584621) | more than 9 years ago | (#9927039)

late Bob Forward
Helvete. Google confirmed. The world is a poorer place.

So that was why he stopped writing. :-(

You miss important stuff when you're too busy.

Re:Ironically (5, Informative)

gibodean (224873) | more than 9 years ago | (#9927030)

I'm surprised that no-one else has mentioned this.

The truth is that a solar sail doesn't get you away from the sun by just having the sail aimed straight at the sun. It does it much more trickily than that :).

What happens is that you orientate the sail at 45% (or something like that) to the sun. That way, a large amount of the force from the sun actually goes to changing your orbital speed, and not just pushing you away from the sun. By orienting the sail so that it increases your orbital speed, you end up making greater size orbits around the sun, until you are far enough away from the sun and you can do some other tricky stuff to leave the solar system.

But, it works the opposite way too. Orient your sail so that you are decreasing your orbital speed. You go slower, and therefore your orbit size decreases, and you start approaching the sun.

Of course another poster queried why you would want to travel to the sun. Good question. But how about Mercury or Venus ?

Phase 1: Deploy Solar Sail (0)

Anonymous Coward | more than 9 years ago | (#9926848)

Phase 3: Profit! (obviously)

my guess ...

"Phase 2: Attach Giant Mecha ... in Japan."

Just imagine... (0)

Anonymous Coward | more than 9 years ago | (#9926956)

a beowulf cluster of these things each carrying a beowulf cluster of "Beowulf" mecha.

Can you power it with farts? (-1, Troll)

Wisgary (799898) | more than 9 years ago | (#9926851)

I'd like a fart sail that would be nice.

gee - solar sail (0)

Anonymous Coward | more than 9 years ago | (#9926858)

But how far did that rocket sail to and speed?

Re:gee - solar sail (1)

tufflove (580300) | more than 9 years ago | (#9926893)

its NOT a rocket........

Solar sail (4, Interesting)

Uplore (706578) | more than 9 years ago | (#9926863)

What I dont understand is how they intend to protect these massive sails from being shot full of holes by meteorites and space dust as it propels its way through space.

Also, seing as how it is powered by solar wind, what happens when the craft is between 2 or more stars which are all exerting equal force on the sails. With no fuel it is doomed to slow down and be 'blown' around in space.

Re:Solar sail (2, Informative)

Anonymous Coward | more than 9 years ago | (#9926874)

please read this [howstuffworks.com] . The work because of the reflectivity. It's not really a 'sail' in the Earthly sense, it's a giant mirror that's only reflective on one side.

Re:Solar sail (1, Informative)

Anonymous Coward | more than 9 years ago | (#9926891)

Ever seen a radiometer? or hear about the radiation pressure equation?

Well it's like this, a dark color like black will help one absorb "at least visible" light, which is converted into random motion of atoms, otherwise a kind of kinetic energy known as hear. But a reflective "color" is different. It doesn't just absorb the momentum. It acctually absorbes twice the momentum of the incoming light, but not the heat energy. The same amount of energy that came in on the light gets reflected out in the opposite direction.

Re:Solar sail (5, Interesting)

whopis (465819) | more than 9 years ago | (#9926981)


Ever seen a radiometer? or hear about the radiation pressure equation?


This is a common misconception... one that even Maxwell mistakenly believed. Apparently along with the folks at Encyclopedia Britannica as well.

Pay attention to which way a radiometer turns. If it were turning due to radiation pressure, it should act as if a force were pushing on the white side of the plates. Since the white plates reflect the light, there should be twice as much pressure on them as there is on the black plates which absorb the light. (It takes a greater transfer of momentum for something to bounce off of you than for you to catch it... think of the conservation laws).


The problem with the radiometer is that it turns the wrong directions... it acts as if something is pushing on the black side of the plates. And there is... air pressure. The black side will reach a higher temperature than the white side, and then due to the thermal transpiration, the gas near the edges moves from the hot side to the cool side, and in doing so it pushes the blades along.


Radiometers are in a near vacuum, but there is enough air pressure inside to allow this effect to happen.

Re:Solar sail (0)

Anonymous Coward | more than 9 years ago | (#9927006)

Right, but as you note, the radiometer will take you to the correct concept for how a solar sail *does* work. Damn that einstien for proving atoms and explaining brownian motion! Nice catch, but still, there's something to be said for having your eye on the ball :).

Repairing micro-meteorite holes (1)

metachor (634304) | more than 9 years ago | (#9926896)

What I dont understand is how they intend to protect these massive sails from being shot full of holes by meteorites and space dust as it propels its way through space.

This is pure speculation on my part, but perhaps some future form of nanotechnology could be used to make self-repairing sales. Implanted sensor arrays would detect discontinuities in the sail-surface and delegate molecular assemblers to patch it.

Re:Solar sail (1)

Sparr0 (451780) | more than 9 years ago | (#9926914)

who cares if it gets knocked full of holes? as long as the dust doesnt hit whatever the sail is pulling, i dont see it mattering as long as the damage isnt total and is roughly uniform in distribution.

Re:Solar sail (1)

erice (13380) | more than 9 years ago | (#9926919)

What I dont understand is how they intend to protect these massive sails from being shot full of holes by meteorites and space dust as it propels its way through space.

Maybe you don't. Just make the sail big enough that to generate adequate "thrust" with a few holes in it. Solar sails are very big and very thin. Any debries that hits is just going to create hole and keep on going.

Also, seing as how it is powered by solar wind, what happens when the craft is between 2 or more stars which are all exerting equal force on the sails

For interstelar travel, you can't rely on the sun. You need big honking lasers in your home system. The light from the lasers will be much stronger than the light from the target star, at least until the probe gets rather close.

Re:Solar sail (0)

Anonymous Coward | more than 9 years ago | (#9926951)

Screw lasers, if you're making a habit of such off world excursions build big ass space mirrors. Let the sun do the work, and be careful not to cook the ship, no need to get carried away and all.

Re:Solar sail (1)

Jetson (176002) | more than 9 years ago | (#9926934)

What I dont understand is how they intend to protect these massive sails from being shot full of holes by meteorites and space dust as it propels its way through space.

They don't have to. The force imparted by the solar radiation is probably not strong enough to cause any holes to expand on their own. They could further prevent tearing using a cross-hatch "rip-stop" pattern of slightly greater thickness.

Re:Solar sail (1)

evilviper (135110) | more than 9 years ago | (#9926935)

what happens when the craft is between 2 or more stars which are all exerting equal force on the sails.

It is directional. It can only be pushed by solar wind from one direction, so unless they turn-around, the star they are approaching will not affect the solar sail much at all.

Re:Solar sail (1)

RedWizzard (192002) | more than 9 years ago | (#9927021)

Also, seing as how it is powered by solar wind, what happens when the craft is between 2 or more stars which are all exerting equal force on the sails. With no fuel it is doomed to slow down and be 'blown' around in space.
As others have pointed out, they are directional. But aside from that, when you are halfway from one star to the next you'll want to start slowing down anyway.

What Solar Sails Are (4, Interesting)

SlashChick (544252) | more than 9 years ago | (#9926866)

In case you, like me, didn't know that much about solar sails, there's a great article at How Stuff Works about them: How Solar Sails Will Work. [howstuffworks.com] Looks like a pretty interesting technology!

Re:What Solar Sails Are (1, Interesting)

Cecil (37810) | more than 9 years ago | (#9927031)

Wow, that surprised me. I thought they actually used the solar wind to power them, not light. But that is not so. The article says the light produces 9 newtons per square mile (3.5 newtons per km^2) whereas by my calculations, an average strength solar wind stream of 1 proton per cm^3 at 500km/s would only produce about 0.0004 newtons per km^2.

Kind of counterintuitive. I thought the unbelievably small mass of a proton would still outweigh the nearly infinitesimal mass of a photon. But I guess our star puts out enough photons to make it count.

Cool, anyway.

Physics (3, Interesting)

caitsith01 (606117) | more than 9 years ago | (#9926869)

Anyone care to fill us in on the rate at which the energy received by a surface decreases with distance? I imagine that, given the incredibly weak force applied by light, it would take one HUGE sail to get anything like meaningful acceleration for space travel. Surely be the time you are a few million kilometres from the Sun the amount of force being applied will have dropped off by a huge amount?

Anyway, we should get to Mars and back a few times before we try to get to the stars... baby steps.

Re:Physics (0)

Anonymous Coward | more than 9 years ago | (#9926890)

IIRC

inverse square law

as the distance doubles the energy becomes 1/4

Re:Physics (4, Informative)

CrankyFool (680025) | more than 9 years ago | (#9926897)

The amount of force exerted on the sail decreases as a square of the distance (since the amount of light reaching the sail decreases by a square of the distance). We're not talking about 'meaningful acceleration' in anything like our current thinking of space travel -- this isn't "get on this space yacht and a few months down the road you'll get to the other star," but rather "put something on this vessel and several hundred/thousand years from now it'll get to where you wanted it to get."

This isn't about travel.

Either way, the Japanese are trying to make this look cool by saying it's star-faring technology. Probably true, but only because we're not likely to put humans on this thing -- so it's possible we'll do this before we get to Mars, because the expense and risk could be vastly lower.

Re:Physics (1)

vantango (719830) | more than 9 years ago | (#9926991)

Why wouldn't it be meaningful acceleration?
If the resistance in space is less than the force exerted on the sail, it should result in positive acceleration.

Remembering that the ship is already moving pretty quickly when it enters space, its velocity will continue to increase until the force exerted on the sail equals the resistance of space (a long time).

Re:Physics (1)

Beryllium Sphere(tm) (193358) | more than 9 years ago | (#9927040)

The acceleration is very low but it operates continuously. Given a choice between a few minutes of using a rocket before it's out of fuel, versus months of gradual acceleration on a solar sail, you can actually get more speed from the sail.

For the foreseeable future the real applications would be inside the solar system.

Re:Physics (1)

symbolset (646467) | more than 9 years ago | (#9926931)

This takes you to the Kuyper belt. From there, ion drive [nasa.gov] takes you the rest of the way.

Re:Physics (0)

Anonymous Coward | more than 9 years ago | (#9926987)

Can't they use the sail itself as fuel for the ion drive, when they are so far away thesolar wind has no effect?

Re:Physics (2, Insightful)

Jetson (176002) | more than 9 years ago | (#9926992)

Anyone care to fill us in on the rate at which the energy received by a surface decreases with distance?

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.

Wrong (5, Informative)

HeghmoH (13204) | more than 9 years ago | (#9926870)

...it is the only technology now in existence that can one day take us to the stars.

Orion [islandone.org] 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. But it's nuk-yu-ler, so it doesn't count.

Re:Wrong (0, Funny)

Anonymous Coward | more than 9 years ago | (#9926875)

"But it's nuk-yu-ler, so it doesn't count."

Yeah, GW's nuk-yu-ler missile shield will shoot it down before it even achieves earth orbit...

Wrong-A "glowing" recommendation. (-1, Flamebait)

Anonymous Coward | more than 9 years ago | (#9926889)

"Orion can take us to the stars"

I don't think there's enough "nuk-yu-ler" to power a spacecraft to our nearest star in a reasonable amount of time.

Re:Wrong-A "glowing" recommendation. (4, Informative)

HeghmoH (13204) | more than 9 years ago | (#9926909)

Sorry, but that is incorrect. There is a design from the late 60s [astronautix.com] for an Orion starship that could get to Alpha Centauri in 130 years, for the whopping cost of $1 trillion. Thats much faster than a solar sail could ever hope to do.

But the Solar Sail exists (0)

Anonymous Coward | more than 9 years ago | (#9926985)

The Orion Spacecraft dosen't. They're right.

Re:Wrong (4, Insightful)

gilroy (155262) | more than 9 years ago | (#9927024)

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.

Are they naive enough to expect... (-1, Offtopic)

Anonymous Coward | more than 9 years ago | (#9926888)

...that they'll make it all the way there before the pirates plunder their hold?

How romantic (1)

syousef (465911) | more than 9 years ago | (#9926933)

We'll sail to the stars.

Please. One poster has already pointed out that this only works within the limit of a star's solar wind. It's also a very slow mode of transport. If you want to send your decayed remanants (even the bones will have disintegrated) HALF way to the stars this is definitely the way to go!

For travel within the inner solar system however, as a secondary form of propulsion it may have its uses.

Re:How romantic (0)

Anonymous Coward | more than 9 years ago | (#9926998)

Are you suggesting that the solar sail would stop after a certain distance? Sure, it will slow down as it gets closer to the target star, but it wont stop just ebcause it leaves the heliopause of Sol.

Re:How romantic (0)

Anonymous Coward | more than 9 years ago | (#9927008)

Allow me to introduce you to a little concept called "inertia."

Or, as it is often expressed, "a body in motion tends to stay in motion."

Ripoff! (-1)

Anonymous Coward | more than 9 years ago | (#9926937)

The Bajorins thought of this first, and
suscessfuly reached Cardassia, much to
the chagrin of the gov't in place on that
planet in the 24th century! :)

My wife (-1, Offtopic)

Anonymous Coward | more than 9 years ago | (#9926942)

would love to buy me something like that.

Not a working solar sail as such (4, Informative)

bigsteve@dstc (140392) | more than 9 years ago | (#9926950)

Quote from article:
ISAS succeeded in deploying a big thin film for solar sail in space for the first time in the world. ISAS launched a small rocket S-310-34 from Uchinoura Space Center in Kagoshima, Japan, at 15:15, August 9, 2004 (Japan Standard Time). The launch was the culmination of a historic new technology, the world-first successful full-fledged deployment of big films for solar sail.
My interpretation of this and the rest of the article is that they were testing deployment mechanisms for sail material, rather than deploying a working solar sail.

The pictures in the article which show the test sail deployed immediately behind the launch vehicle imply the same thing. The following text says that the launch vehicle reentered and splashed down 400 seconds after liftoff. This can only mean that both the LV and the sail experiment were in ballistic flight when the latter was deployed. For a solar sail to work, it would need to be deployed after orbital insertion (or after escaping the magnetosphere.) The article does not mention orbital insertion, nor was there time for this to occur.

Exactly - robotics competition coming too (1)

apsmith (17989) | more than 9 years ago | (#9927000)

At the SPS 04 [congrex.nl] meeting we heard about a planned launch in a couple of years of something very similar - a suborbital rocket with 20 minutes or so in space at zero gravity, which will deploy a large triangular mesh intended to resemble a possible structure for a solar power satellite. Then two or three teams of robots will be competing to maneuver about this mesh under vacuum/zero-g conditions, and see how far/fast they can go, and what they can do. One of the teams involved spoke - they seem to have previously had something to do with playing Robotic Soccer [fira.net] .

photos (1)

theirishhombre (801622) | more than 9 years ago | (#9926960)

I'd expect more photos from a Japanese space craft's liftof. (ie space tourist)

Good to see (3, Interesting)

T.Hobbes (101603) | more than 9 years ago | (#9926967)

It's very good to see this branch of space technology getting funding. I'd rather travel in a starship with warp drive, but until then we need some feasable way to get to other stars. There's no reason, in my mind, why we shouldn't send a few of these off to nearby stars with the sole purpose of taking some close-in measurements and somehow getting the data back here (getting the data back would probably be harder than getting the spacecraft there in the first place). The very fact that it would take hundreds or thousands of years for them to get there is the best reason to start sending them now.

Let's all raise a glass of Sake to the engineers behind this project!

Not so fast... (1, Insightful)

Bill_Royle (639563) | more than 9 years ago | (#9926972)

"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."

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:Not so fast... (1)

imaginate (305769) | more than 9 years ago | (#9927015)

Umm... turn around.

I hope that was intended to be funny.

Re:Not so fast... (1)

Bill_Royle (639563) | more than 9 years ago | (#9927028)

And how do you plan on landing? In a pretty little spiral?

Re:Not so fast... (4, Informative)

gilroy (155262) | more than 9 years ago | (#9927036)

Blockquoth the poster:

This may be true, but it'll take another technology to take you there safely: brakes.


Um, no. As you approach the destination star, its light pressure will start to counteract your velocity and slow you down. The "brakes" are built in.

Creepy fortune at the bottom of the page: (0)

Anonymous Coward | more than 9 years ago | (#9926984)

But I was there and I saw what you did, I saw it with my own two eyes. So you can wipe off that grin; I know where you've been-- It's all been a pack of lies!

Could this be used with other rockets? (1)

JazzXP (770338) | more than 9 years ago | (#9926986)

Would it be possible to have a rocket as well as a solar sail? The rocket for the inital acceleration, then use the solar sail to keep accelerating (much more energy efficient).

CG? (1)

xoboots (683791) | more than 9 years ago | (#9926993)

Is just me or do those press photos look like they are CG? Circa Doom II.

Interstellar travel it wasn't. (4, Informative)

Alsee (515537) | more than 9 years ago | (#9927009)

They deployed a sail less than two minutes after launch, had it in place less than two minutes, threw it away, deployed a second sail, then less than three minutes later it crashed into the ocean.

Total trip, liftoff to crash-down, less than 7 minutes.

-

Not wind! (3, Informative)

Anonymous Coward | more than 9 years ago | (#9927019)

Just to clarify what people seem to be mistaking, the sail is *not* powered by Solar Wind, it is powered by the light of from the sun. The idea is that each photon of light that reflects off of the surface of the sail transfers a little bit of it's momentum to the sail.

Solar sailing (4, Funny)

antikarma (804155) | more than 9 years ago | (#9927022)

It won't be a viable method of transportation between solar systems until it has an anti-pirate defense system. Giant solar sails just scream "come and get me space pirates."

2 questions (Earth altitude, Sol heliosphere exit) (3, Interesting)

MMHere (145618) | more than 9 years ago | (#9927038)

1. Did they get high enough above Earth to enter the inter-planetary "void," and thus avoid the significant effects of Earth's atmosphere? 100, 230, and 400 seconds after liftoff hardly seem "high enough."

2. What happens to such sails when they cross the heliosphere of a regionally prominent star such as Sol? Is it all chaotic photons and miscellanous radiation in the interstellar "void?" Or are conditions regulated by the nearest stellar bodies?

-- In other words, how would one navigate effectively once the prominent wind from Sol fades and is replaced by other forces? Are you doomed to follow your trajectory mainly established by Sol once you leave its heliosphere, possibly modifed by various minor (uncontrollable) forces from other winds in the void? Can you take advantage of such extra-Solar winds to go where you want?

Just a question... (4, Interesting)

ScottZ (14863) | more than 9 years ago | (#9927047)

How do you run against the solar wind? What are the appropriate forces to run your 'keel' against when you want to track across a solar system (say, to somewhere useful)?

Anyone got any pointers?
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