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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.""
"...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.
You are confusing me with someone who cares.
Does this mean that plans for taking the flying steam-powered train to the stars is cancelled?
Havin' it large, livin' the life, Welcome to the land of the rising sun.
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...
Evan - needs to hit preview before submitting
Phase 3: Profit! (obviously)
...
... in Japan."
my guess
"Phase 2: Attach Giant Mecha
But how far did that rocket sail to and speed?
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.
Tweet, tweet.
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.
I couldn't think of a sig.
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. Looks like a pretty interesting technology!
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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.
Read Pynchon.
...it is the only technology now in existence that can one day take us to the stars.
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. But it's nuk-yu-ler, so it doesn't count.
Mod down posts with a "Free Mac Mini/iPod" sig, they're spam!
Solar Anchor :)
Rus
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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.
Sorry, but that is incorrect. There is a design from the late 60s 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.
Mod down posts with a "Free Mac Mini/iPod" sig, they're spam!
You just have to tack into the solar wind. *grynn*
You heard it hear first -- America's Cup 2200.
---anactofgod---
---anactofgod---
"Equal opportunity swindling - *that* is the true test of a sustainable democracy."
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.
These posts express my own personal views, not those of my employer
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".
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.
a beowulf cluster of these things each carrying a beowulf cluster of "Beowulf" mecha.
I'd expect more photos from a Japanese space craft's liftof. (ie space tourist)
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---
---anactofgod---
"Equal opportunity swindling - *that* is the true test of a sustainable democracy."
Let's all raise a glass of Sake to the engineers behind this project!
"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...
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.
This is a reference to Galaxy Express 999. It's a joke near as I can tell. Not a fair mod in my eyes
Hi! I make Firefox Plug-ins. Check 'em out @ https://addons.mozilla.org/en-US/firefox/addon/youtube-mp3-podcaster/
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!
The Orion Spacecraft dosen't. They're right.
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).
Is just me or do those press photos look like they are CG? Circa Doom II.
At the SPS 04 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.
Energy: time to change the picture.
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.
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- - You can't take something off the Internet! That's like trying to take pee out of a swimming pool.
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.
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."
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?
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?
The light weight and lack of propellant make this an ideal platform for interplanetary endeavors, even for lifting satellites into high Earth orbit cheaply. Much of the cost of a mission is getting the weight out of Earth's gravity well, and the weight of boosters for that must be lifted by the lower stages.
First of, I am not a trained professional. I am a high school senior but I believe that I understand the principals behind this technology. The term solar sail is a modern misnomer. Solar sails are only capable of accelerating away from a star. This is because the sail is powered by reflecting solar radiation/solar wind. (I'm not sure, but I believe that this is limited by the inverse square law, which means that every time you double the distance between you and the source of the radiation, you decrease it's power 4 times. AKA it's power decreases exponentially as you travel away from it.) This means that in the expanse between stars, there will be essentially no acceleration, and in fact, depending on the size of your sail, some drag. Because space is not really empty (one hydrogen atom per square meter, which would add up if you need to travel light years with fully deployed several KM wide solar sails.) While the best way to use solar sails would be to put human power behind them, that is to fire lasers at the sails to continue powering them past the heliopause, enabling them to continue accelerating past our solar system. The simple option for travel would be to have a craft capable retracting it's sail, retract its sails once it leaves the area of acceleration, and then deploy them once it arrives in it's target solar system, slowing it down. Solar sails are also impractical for travel in a solar system (with the exception of traveling from an inner plannet straight out to a planet more distant from the sun.) Solar sails can not function like sails on an ocean. The reason sails work on an ocean is because boats have centerboards, solar sail craft do not have centerboards (because space doesn't have the matter to support one) they would simply drift away from the sun. Conclusion: Solar sails, while wonderful and interesting, will never have a practical use transporting humans simply because it would take hundreds of thousands of years to travel between stars. I also believe that if we begin constructing solar sail craft to travel to distant stars, we should (if we don't we are doing something wrong) be able to travel to the star and back before a solar sail craft would get there to begin collecting data. If I screwed up anything flame me as much as you want.
In nature, there are neither rewards or punishments, there are only consequences.
Rest Mass from Wikipedia
A clover type deployment was started at 100 seconds after liftoff at 122 km altitude, and a fan type deployment was started at 169 km altitude at 230 seconds after liftoff
But a laser pumped solar sail could be faster. Those big laser will be a big investment, though... and the "misuse" applications should be about the same as for lots megaton bombs! (It's mentioned e.g. here.)
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I didn't see anything in the article saying how big the test sails were. Large ultralight structures have to be pretty ungainly to handle even in zero-g, and designing effective deployment and handling systems can't be easy. Imagine what it takes to steer a fragile gossamer object like that!
Microsoft has currently installed Sol on our computers even up to a decade ago.
Hit WINDOWS KEY + R type in SOL ENTER
Sol is right here, no need for travel!
Didn't Count Dooku - aka Darth Tyrannus - have one of these? Probably not the fastest vehicle for escaping Yoda's army of clones, but maybe it leaves no heat signature or something ;-)
When I am king, you will be first against the wall.
Looks more like a solar parchute.. Compared to a sail on a sailing boat that can actually sail back to the location from which it came.. how are they going to get back with that thing. Thinking of how we use resources on earth maybe their isn't anything worth coming back to..
If I understand solar sails right, they are actually pretty different from the way wind sails work. Contrary to what your NASA links is telling us, most of the force from the sail does *not* come from the wind trapped in the sail pushing it along. Rather, under the pressure of the wind, the sail takes the form of a wing, and Bernoulli forces propel the boat along. This also enables sailing (up to a degree depending on the craft and the rigging) against the wind. I do not see how Bernoulli forces would appear on a solar sail (as the light can't go faster on one side of the sail than on the other).
how they are going to produce an untra-thin and ultra-light solar sail on such a gigantic scale? I forgot the ratio but it's going to take an ernormous sail to propel even a few kilograms. The only reasonable analogy I've heard is painting wax with a silver pigment and then melting the wax away, but that still leaves an important issue: The smalest speck of interstellar dust will leave a sizable hole in a sail so thin and light. How far can something like thins make it? Even space isn't a truly zero friction environment.
Send Texas and the Middle East to another planet? That would satisfy both sides, right?
A clover type deployment was started at 100 seconds after liftoff at 122 km altitude, and a fan type deployment was started at 169 km altitude at 230 seconds after liftoff
Oops, I meant to title this "Origami in space!!!", not "Ortw" but I accidently hit "Enter" and Slashdot's unforgiving code irrevocably posted it.
the problem with shooting lasers at the sails would be that it wouldn't help much, just waste energy, everytime you gave off radiation pointed at the sails it would push the ship back when it went off and then push the sail the same amount, unless you meant that we should push it from earth.. in which case as you got farther away it'd get worse and worse with aim and you could veer off course since the light would take so much longer to get there it'd take longer to make a course correction.
This reminds of the Deep Space 9 episode in season 3 where Sisko builds a primitive Bajoran sail ship and attempts to fly to Cardassia with it.
-- Get
These solar sails are pretty useless. Here http://solarsails.jpl.nasa.gov/introduction/design -construction.html
are calculations from NASA guys. It looks like this
Japanese sail has acceleration of few mm/s^2 and is not able to get out of sun gravitational field (and, of course, the Earth's one). It would take solar sail 100 years to get
to alpha centauri if it had acceleration 10 m/s^2 (table 3 in the above link, there is "-" in the
table for 5 m/s^2 and less , that is it will never get away from sun ).
There was a good idea though to build a huge mirror to focus sunlight on such sail. This would effectivly increase surface area of a sail and
pressure would not drop as square of the distanse from the sun.
The Gripping hand
I can't tell if they were terrible books, or great books, but either way I really enjoyed them.
I dunno if Arthur C. Clarke was the first to introduce the concept of Solar Sails in it's short story 'The Wind from the Sun', this is one of the things that got built in the mans liftetime... Btw, in the story, solar storms would cause the fragile sails to break apart.
"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."
Bollocks. What about a very big flashlight wired to a nuclear reactor?
1) This would keep generating light-pressure for the whole journey to a nearby star - even in the dark middle part.
2) You don't need lead shielding in space, so I bet that pound-per-pound, a nuclear reactor would produce far more energy (and hence accelleration) than a mirror.
Can I patent this in Japan?
Yes, it keeps accelerating over long distances....but I can make a rocket do the same thing by asymptotically slowing down the rate of fuel burn. A solar sail is doing nothing differnt, while the sail will keep accelerating the accelaration will fall off with the radiation pressure (about 1/r^2).
Personally, I tend to believe things like ion drive are actually much more efficent and likely to work well with stare exploration (ion drive is just a fancy way of saying you shoot very small amounts of mass out the back going very fast. This is important because it means you can get more thrust from the same amount of fuel weight if you have something like a nuclear power source to accelerate the ions).
If you liked this thought maybe you would find my blog nice too:
For the first time in the world in thin film sail development for "Solar sail" success (Uchinoura)
# Sorry, but I have no time to translate manually
Those pictures make it look like Vejur, coming to cleanse the carbon-unit infestation from the Creator's planet...
You must think in Russian.
to the crew on board, it'd be like
mere hundreds or even tens of years
Not according to general relativity: they need
to accelerate when leaving, and decelerating when
arriving to destination. Decelerating will almost
reverse any time compression from the
relativistic speed...
One rule I've observed is that it doesn't matter WHAT you strap to your flashlight, or how many spares you bring, by the end of the week you WILL be in the dark.
Banaaaana!
For those of you who are - like me - not experts in physics, this technology was featured in the BBC documentary "Space" presented by Sam Neill.
c at ,5,,11,science,831
http://www.imdb.com/title/tt0273608/
http://www.bbcshop.com/invt/bbcdvd1090&bklist=i
One of the chapters discusses how travel to other stars would be possible. As far as I remember there is another technical solution in discussion which would involve nuclear detonations as part of a propulsion system. (I might have confused something there, though)
Easy: double suicide.
I don't dare to speculate about the gruesome events that the venerable pong may trigger...Niven was slyly referring to when Archimedes actually DID that. Archimedes used a burning mirror to defend the harbor of Syracuse against the Romans.
This website has a list of many advanced propulsion technologies under devleopment by JPL. Considering that we are using chemical rockets which have been known about since the 30's it's good to see that people are looking into new propulsion tech. These systems, some of which can reach the speed of light, include Advanced Chemical Propulsion, Nuclear Propulsion, Antimatter Propulsion, Electric Propulsion, Micro Propulsion, Beamed Energy, Sails, Gravity/AeroGravity Assist, Chemical and Electromagnetic catapults, Tethers Skyhooks and Towers,Extraterrestrial resource utilization,etc.
The actual plan is to angle the sail at 45 degrees to the sun, accelerating it in *orbit* around the sun until it reaches a reasonable velocity. Then you set out.
This has been said in other posts, but it has a clear relevance to your point in particular. The orbital radius will remain fairly low for a much longer time than you imply. Force is inversely proportional to the square of the distance, but distance will not be directly proportional to time spent accelerating.
It's also not correct that solarsails can't be used to reach other suns, because the sun there gives an oposite force. It's quite trivial, when using adaptive (rotating) solarsails, which have only one higly reflective side, to slow down or accelerate when nearing a solarsystem. And even withing a solarsystem; for an interesting project in that regard, see the planetary society where they plan to launch the first non-gov solarsail-powered probe.
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slashdot needs fart jokes
Count Dooku has had a bitchin' solar sail for years now. Old news.
that would be robbIE.
What the hell is wrong with you? You hear of a well-thought-out idea developed, examined, and approved by physicists, and without looking into it, you dismiss it with your first couple of off-the-top-of-your-head thoughts.
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.
Hasnt anybody read this story by Arthur C. Clarke about an Earth to Moon race in solar sail powered space ships.
A beautiful story with an excellent description of some problems which may exist.Read the story,i will spare the spoilers.
Wanted : A Signature.
I can't find anything about this in the main stream media, the only story Google News finds (at least at the moment) is this which is talking about NASA and a recent on-the-ground test deployment.
Anyone actually got any more hard facts about this one?
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I'm not a physics expert by any means, but I do recall that that momentum is conserved. If the spacecraft has been moving away from the source star and toward the destination has it not built up a bit of momentum? And to stop at the target star would one not have to kill that forward momentum? That is: if this were a rocket, wouldn't one flip the spacecraft at midpoint and begin decelerating? Why should a solar sail be any different? As for the front needing to be non-reflective: wouldn't a far more efficient technique be simply to contract the sail thus reducing the area and the overall thrust?
I'm probably wrong: I am not a rocket scientist.
...in Japan.
There is another existing technology that could travel interstellar distances. NASA's Orion project designed a starship propelled by nuclear weapons and a big pusher plate. And yes, the crew can be properly shielded.
Of course what we really should be working on is actual nuclear rockets - controlled nuclear burn instead of explosives. Nuclear gas core rockets are really not beyond present technology, their exhaust is cleaner than the space shuttle's, and they're so powerful you can build big, heavy, safe vehicles.
"The danger is not that a particular class is unfit to govern. Every class is unfit to govern." - Lord Acton
Okay, everyone. Let's calm down. The Japanese, or any other Earthlings, will not have to worry about changing their velocity at Alpha Centari anytime soon. The fact is, all they accomplished was opening two differently shaped pieces of foil above Earth over a 400 second period.
Please. I used to launch Estes rockets with shiny parachutes. Prove to me that it WASN'T photons reflected from the Earth into my solar parachute that were slowing my rocket's descent. So NASA, ISAS, and 14-year-old model rocket enthusiasts have simply proven that gravity will pull anything you launch into the sky back to Earth.
One problem. Let's say you have a small crew, and the supplies they need to last even a couple years. Figure out the size of a sail to even accelerate at 0.01g. It would be a massive sail, probably measuring tens of kilometers in diameter. The larger the sail, the more debris that you hit.
I believe the size of the equipment that is sent up in solar sails measures under 100kg. Could be wrong...
No, the parent is saying that if you want to push off of something to stop you at that rate of speed, it will need to be very massive.
I would think that you could just rotate the entire assembly around once you get close to the destination to slow down, turing your solar sail into a "solar parachute".
I'm a good cook. I'm a fantastic eater. - Steven Brust
You can definitely use the gravity of a large body to either slow down or "slingshot" you to speed you up.
.
Um... not relative to that particular body you moron.
The entire point of slingshotting is that after a gravitational interaction with a body in space, when you come back out to the same level of its gravity well, you're going at the same speed relative to that body, but possibly in a different direction. So, if you're going at the same speed relative to that body, but more in the direction of that body's travel, you'll be going faster in the frame of reference where you consider the body to be moving.
So, if you want to get out to Neptune, you can use Jupiter to get a boost, or if you want to come
Anyway, the mechanics of interstellar travel are completely different from interplanetary travel. Interplanetary travel is all about orbits, interstellar is simple linear acceleration and deceleration. There are no fancy tricks, just powerful rockets with dense fuel sources, the possibility of an energy/momentum stream to ride (laser or particle beam from the home system), and the thin interstellar medium as a possible fuel/braking/steering source.
I won't go into the other stupidities you posted.
Can someone in the know answer me this:
Since a solar sail needs light pressure to accelerate, can it only accelerate in a direct line away from a star?
also
Isn't there a problem, once the sail gets far enough from its original star, that pressure from other stars will interfere w/ the path?
"I must not fear. Fear is the mind killer." -Bene Gesserit Litany Against Fear
Um, no, you dumb shit. It is powered primarily by solar wind, the stream of charged particles from the sun. Being massive particles they have much more momentum.
There will be a miniscule effect from the light, but most of the boost comes from the solar wind.
Jesus... if you don't actually know DON'T CLAIM TO BE CORRECTING PEOPLE WITH THE FIRST THING THAT POPS INTO YOUR HEAD. Go look something up for once.
http://spacescience.com/headlines/y2000/ast04oct_1 .htm/
I think this is a very interesting technology, and it's been around for 4 years. Basically it's a couple of really powerful magnets creating a small magnetic field around a craft, and pumping it full of low energy plasma (Argon and Helium)to increase the size of the field.
In the article they mention a 15km target size for the field, which should capture about 600kw of energy from the solar winds at a cost of 1kw of power, and less than 1kg of fuel per day. I'm not sure whether they'd be able to capture helium and argon in space, but I'd say it's definitely worth looking into.
IANARS (I Am Not A Rocket Scientist)but it looks like this may solve the problem of slowing the craft down, by either changing the alignment of the magnetic field, or reducing power to the field.
It should also provide an additional layer of radiation shielding to any sensitive cargo on-board the craft, whether it be manned or not.
Maybe one of the other /. readers knows a bit more about this?
A large budget doesn't change the fact that it's littering. If mylar balloons have a negative effect on sea life, what about these big sheets?
What you're missing here is how big this sail would have to be. To get a meaningful acceleration, you'd probably have a big, flimsy sail several thousand square kilometers in area; and once you have that, who cares if you lose a few square kilometers now and then?
The other factor is that once you get outside the solar system, the matter density should go way down; not much dust, virtually no chance of large rocks. Sure, they're out there... but odds are that you'll never hit anything capable of taking out a major percentage of the sail.
"Science is a way of trying not to fool yourself." -Richard Feynman
The force of the solar wind is on the order of 1000 times less than light pressure.
Another option is to use gravitational effects; i.e., the same "slingshot effect" used to boost Galileo to Saturn. IANARS, but I'm pretty sure the same principle can be applied to kill off velocity. (Takes a long time, but what's a couple of years after an interstellar voyage?)
There's also aerobraking, if you know there's a planet with an atmosphere available. Although I'm not sure I'd want to kill off that much speed with friction. Ouch.
All of this assumes a awfully fine degree of maneuvering precision using just a sail. It's hard enough with sailboats on water, and they have the benefit of a rudder and keel. I suspect some kind of reaction-based propulsion system (ion drive?) would be desirable for the end game.
There is another solar sail project: http://www.planetary.org/solarsail/index2.html. It is supposed to get on orbit on russian missile launched from russian nuclear submarine. They seem to be working on this for several years. Their work seam real, but it could be just hoax targeted to get "sponsor" money - the indication of this is that they keep postponing the launch for several years already.
and back again, that's the sailors way!
It's efficient, but not fast. Good for unmanned probes, since you don't have to build a booster. It's not the end-all-be-all of rocket propulsion, but it's certainly workable for selected tasks.
I ran across this novel form of propulsion the other day that looks promising if it pans out.
The idea is to entangle two cesium atoms, then send one up into space. Back on earth, excite the one that remains and the one in space will do the same. In theory that could be used as an ion drive while keeping the bulk of your engine back on the ground.
Have fun using this "sailing" vessel to traverse the Ort cloud. Try crossing ice berg infested waters at over 70,000 mph!
I know from experience: Have you ever played Asteroids while at full thrust!? You last about 15 seconds tops. Now just add a big friggin' sail to act like a drift net and you've got a gourmet recipe for disaster.
I'd rather try my luck playing golf in a thunderstorm.
Authority questions you. Return the favor.
If you turn it around to slow your fall into the next system, then it becomes a solar parachute, right?
A solar wind, by the way, isn't just the light. It's a very light breeze of all of the particles that the sun throws out as it burns (explodes). At something like three times the orbit of Pluto, these particles loose enough momentum that they're completely countered by the existing particles in deep space. That's the heliopause. You'd definitely have to close your sail at that point.
Has anyone ever calculated how much speed you could get from a solar wind? I'd like to see an experiment to measure one.
The concept of whether light-sails would work is still very much in doubt. There are people on both sides of the debate of whether you can push yourself along by reflecting light. The idea that photons act like pingpong balls to push you along makes sense, but apparently the physics doesn't pan out.
Wake up - the future is arriving faster than you think.
It looks like something done by a child at a school play.
> 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.
No solar-sailors would ever jettison their sails. That's like going out to see and throwing your sails into the water.
Once the solar-sail gets past our sun's heliopause, there is *no more solar wind* to push it further out. By that time, the sail has accumulated as much velocity as it will ever get. All it can do from there to the target star-system is coast. The crew would fold up the sail to prevent damage to it.
To slow down when approaching the target star system, just hoist the sail again, but point it away from the direction of travel. The target star's wind will naturally slow it down.
If we could have just tried Orion, we could have landed full-scale bases on the moon, mars, and wherever else we wanted them with only a handful of launches. And we would have done this more than 20 years ago.
We've lost the tooling now to even make more of the Saturn V rockets we used to have. The only reason NASA can even do as much as it does anymore is because they can take advantage of miniturization to fit more in their tiny payloads. That and having Russia save our butts on the station.
It makes me sick.
Hmm, along the lines of SETI@Home, we could ask everyone to point a $3 laser pen at a solar sail to help it go faster. The difference in acceleration could even be measured and posted to a website, live. Hah!
[ReidNews]
Meen we can make sails what can go through the pacific,a f2 tornado, and even survive a modest waterspout. But these fancy Doctors and Masters don't think a solor powered ship can slow down...that's funy.
Are you thinking of the Galaxy 999? :-)
I would think you'd use chemical rockets for course correction and maneuvering jets.
The thing I am wondering could you use lasers on the ship to power the sails?
How do you stop at the other end? It's obvious with Orion or a normal solar sail, but where does the energy come from with a laser pumped solar sail?
If you use a stationary laser to push the ship away from the solar system, how will it be able to stop when it gets to its destination? Presumably the laser provides greater acceleration than the solar wind, and so you wouldn't be able to slow down as fast as you sped up.
Has anyone calculated what the maximum speed for one of these would be? There must be a limit on how large you can make the sail and still deploy it in a reasonable amount of time. I guess you could shot it toward the sun before deploying the sail.
Stop at the other end? I suggest we start worrying about it when we get there. :)
Future Wiki -- If you don't think about the future, you cannot have one.
Having read TFA, I noticed that the two sails were deployed at heights of only 122 km and 169 km altitude. Which means they'll probably be orbiting the earth (or with not enough tangential speed, they dropped down). But are they making it to another planet or (a couple more slashdot stories later) to the stars? I think it will take many rounds before they can leave the earth's gravity, stop circling around the earth, and be on their way. And how many other satelites will they mop up on their ascent to higher orbit? Questions, questions...
Bert
Who is probably posting this too late to get a response
Unless somebody is hypothesizing that photons exhibit a red-shift when they bounce off of a mirror?
The Web is like Usenet, but
the elephants are untrained.
What is it's mission?
-- http://uncannyvalley.org/
Ummm. Photons have momentum. For this *not* to be transferred to the solar sail would be a violation of conservation of momentum.
Strangely, according to its table of contents, the article on Howstuffworks has a chapter called "Shop or Compare Prices".
I couldn't find any prices for a solar-sail-powered spacecraft, though. I guess if you have to ask, you probably can't afford it.
Attack its weak point for massive damage!
if we launched one of these things tomorrow, and pointed it at alpha centauri, how soon would it get there?
Its fairly obvious that the solar wind, not sunlight would be propelling this object in the inner solar system. The solar wind is made up of ions expelled by the Sun http://science.nasa.gov/headlines/y2001/ast31jan_1 .htm
Though Solar Sails are often associated with interstellar travel they have many extremely useful applications in Earth orbit and local solar system exploration. Most potential applications take advantage of the continuous thrust and zero fuel payload of a solar sail. Near Earth, Solar Sails are particularly suited for high orbital inclination satellite missions. Weather forecasting and global positioning systems would directly benefit from satellites orbiting the poles. Most satellites take advantage of the natural speed of Earth's rotation to boost them into an orbit relatively close to the equatorial plane. Changing the plane requires a large fuel burn for a conventional rocket and greatly increases launch costs. With its small but continuous thrust, a solar sail can reach polar orbits without a massive fuel payload, making them more accessible to scientific research. Away from Earth, Solar Sails offer a number of other interesting options. Missions have been proposed for asteroid rendezvous, travel to the inner planets (yes, solar sails can travel toward the sun), and an interesting idea using Lagrange points. More advanced solar sails could use their continuous thrust to enlarge the regions where they are able to "hover" well away from Earth. This allows much better observation of solar activity. Solar sails not only have an appealing sci-fi flair, but appear to be quite practical as well. I hope to see the technology develop rapidly.
The Planetary Society is planning to launch their Cosmos 1 solar sail later this year. It was built in Russia, and will be launched from a Russian submarine, aboard a converted SS-N-18 ballistic missile. The Cosmos 1 solar sail has multiple triangular vanes, and looks a little like a windmill.
What happens when you star approaching a star, will the light particles from that star slow it's speed?
The bad part is that the "dumb shmuck" is modded down to 0, so it looks like he comments on my post above. :-)
Karma: Excellent (My Karma? I wish...:-( )
ISAS succeeded in deploying a big thin film for solar sail in space for the first time in the world
(a quote from the article)
"first time in the world" doesn't quite seem an appropriate expression...now does it?
Logic, macros, and more
Can anyone confirm that the sails are in orbit? (or not) Whilst watching for Perseids tonight (in the UK) I spotted something which appeared to be a satellite, but it's brightness was varying from "quite bright" to "invisible". My first thought was "rotating/tumbling satellite" but the variations were not regular. Viewing conditions were reasonable, with some high misty clouds, but not enough to account for my losing sight of the object. It occurs to me that a sail in orbit might produce this effect. First time I've seen anything like that in many years of skywatching! (Oh, and I saw half a dozen good Perseids too :) )