NASA to Launch Solar Sail 147
arbitraryaardvark writes "Physorg reports that NASA will launch a solar sail around the end of July. It'll be the first of its kind; a previous attempt blew up. It's a small proof-of-concept gizmo, not a full-on spaceyacht.
Solar sails operate on photon pressure from sunlight. They are well known to science fiction readers, otherwise not so much." C-net has coverage, too.
Ah, sigh (Score:5, Funny)
Re:Ah, sigh (Score:5, Insightful)
Re:Ah, sigh (Score:5, Insightful)
"Yeah well, Hollywood and {science, art, engineering, law, philosophy, history, fantasy, ...} haven't ever mixed well, for the most part."
There. Fixed it for you.
I'll give you a hint. Hollywood is like a marketing department at an engineering firm. They have learned very well that they don't need to understand the product to sell it. Package a movie with a couple of hunks and babes as well as some explosions and dramatic music, and nobody is going to care about its accuracy.
Re:Ah, sigh (Score:5, Funny)
Package a movie with a couple of hunks and babes as well as some explosions and dramatic music, and nobody is going to care about its accuracy.
Well, except sad bastards like us.
my parents (Score:4, Funny)
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Hollywood is like a marketing department at an engineering firm.
A unicorn is what's left of the engineer's rhinoceros after marketing gets done with it.
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Hollywood is like a marketing department at an engineering firm.
A unicorn is what's left of the engineer's rhinoceros after marketing gets done with it.
I always thought it was the other way around...
Oh wait, that's after upper management gets done with it.
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Stupid disney and their stupid wooden ships in outer space.
And stupid children too dumb to even think about questioning any of it.
Re:Ah, sigh (Score:4, Insightful)
Joke, right? Because know a lot of science fiction movies that contain some very rotten science, doesn't mean they're bad films only that you shouldn't take it as a science class. I'd rather have entertaining entertainment than accurate yet extremely boring movies. Yes, I know that in space noone can hear you scream but I don't care when the star destroyer comes "whooshing" by. And that most things don't blow up like they were packed with dynamite. If you didn't learn that outside the movies, maybe the problem is that you take all your learning from movies rather than the movie...
Re:Ah, sigh (Score:5, Interesting)
Re:Ah, sigh (Score:4, Informative)
Almost right. The revised version of 3 pages of technobabble became "Reverse Course!", not "Turn around!'
Re:Ah, sigh (Score:4, Informative)
At the risk of replying to myself, I believe that story was first related in Whitfield's "The Making of Star Trek".
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Makes sense .. no one would believe Kirk was up on that much of the technical details and that the crew wasn't. If my captain had to explain to the crew how to turn the ship around, I'd be looking for the life boat.
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I'd rather have entertaining entertainment than accurate yet extremely boring movies.
I'd rather have entertaining entertainment with accurate science movies.
The two are not mutually incompatible like many people like to imply. e.g. 2001. The basic problem is that most Hollywood types are scientifically illiterate, are actively proud of it and don't care that they're not very entertaining to people who are scientifically literate. Many movies are like fingers on a blackboard. e.g. The tilting helicopter in
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Yes, I know that in space noone can hear you scream but I don't care when the star destroyer comes "whooshing" by.
This always seemed like a weird pedantic objection to me. If your ears were exposed to the vacuum of space you'd have bigger problems than not hearing spaceships. Why not question the fact that there's an all-seeing camera fraudulently providing the visuals?
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cork has been used for the heatshield of several reentry capsules. Wooden components have seen limited use in space- but wood is also becoming a hitech (composite) material in many ways so expect more in future perhaps. In the deeper future when plants are grown in open space (bamboo seeded asteroids, baby) then we will build entire hulls from plant fiber and epoxy.
Cork reentry shields (Score:2)
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Funny, that's how you get from Bajor to Cardassia as well.
Photon Pressure (Score:2)
What's worse is they could read slashdot and believe that they work by photon pressure rather than solar winds. What next? Does reentry burn you up because of friction (rather than rapid pressure change)?
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Sadly, my kids think a solar sail is something you put on a wooden ship to power the ion thrusters. Stupid disney and their stupid wooden ships in outer space...
The annoying part is that other than that, it was actually a fun movie, but that was a little much. I actually much preferred Titan A.E., which wile not exactly super-realistic, did at least have action-reaction in space.
Re:Ah, sigh (Score:5, Informative)
Is there anything wrong with the idea of combining solar sails WITH Ion thrusters? Both should be light weight, not require a large energy source, and theoretical light speed acceleration.
Ion engines still need fuel. Ions, to be precise. Just because they use electricity to accelerate them (instead of some kind of combustion process) doesn't mean that the energy doesn't have to come from somewhere, so now you need an energy source. Which is either solar (cutting into your available area for a sail and becoming increasingly infeasible when you get away from the sun) or nuclear (which means enormously heavy: RTGs are many kg per Watt and a full-blown reactor weighs tons before you've generated the first Watt).
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Which is either solar (cutting into your available area for a sail and becoming increasingly infeasible when you get away from the sun) or nuclear (which means enormously heavy: RTGs are many kg per Watt and a full-blown reactor weighs tons before you've generated the first Watt).
Or you can make the solar sail out of a flexible solar panel and kill two birds with one stone.
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Re:Ah, sigh (Score:5, Interesting)
Every time I read something like this ("but that's impossible!"), I think about 1900. Amazing the number of things that were "impossible" in 1900 that we do routinely now....
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except, they're primarily marketing the technology as a 'power' solution for RFID, they haven't got approval to sell the product for use as home solar power, and they have a lot of plans, and no customers. that's never a good business model, especially since you switched from an in house, proprietary manufacturing to some untested system using inkjet printer hardware... how long will these devices last, even if they can be printed on plastic... if they're targeting RFID devices, i got a feeling they don't
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Obviously the photons absorbed gives you only half the momentum of the photon reflected, but as solar cells absorbs photon only on some frequency range, the other could be reflected, so you'd loose less than half of the momentum.
But the weight of the solar cells is probably much higher than the weight of a normal solair sail..
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Anywhere with enough solar energy to use a solar cell or solar sail probably has enough particle density (from the solar wind) to use an ion thruster. You don't need a lot of mass to make a thruster, just accelerate each particle to really high velocities. There are engineering problems, but you can't dismiss it out of hand.
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[...] Which is either solar (cutting into your available area for a sail and becoming increasingly infeasible when you get away from the sun) or nuclear (which means enormously heavy: RTGs are many kg per Watt and a full-blown reactor weighs tons before you've generated the first Watt).
.... unless, of course, you are using a bussard reactor [wikipedia.org]. not all kids get science from movies, i got mine from sci fi books. they can be imprecise to the point of criminal, or incredibly visionary. bussard reactors are beyond our technical capability now, but try reading up Jules Vernes remembering when he wrote his books. describing a moon landing when all the population used horse drawn carts is no different from what sci fi does now.
P.S.: bussard reactors were described, in different configuration
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First time I've had mod points and a story accepted at the same time. But I might want to comment, so I'll just say mod parent up.
What other type of vehicle could a solar sail and Ion thruster be used for?
Robot ninja asteroid pirates?
The 2024 Honda hybrid?
Adding an ion thruster adds some weight, and solar sails tend to work better with low payload vehicles, but yeah, that seems to work.
Maybe the ion drive could be jettisoned once it runs out of fuel, if it's still close enough to the sun/a star that the sa
What a stupid generalisation! (Score:4, Funny)
They are well known to science fiction readers, otherwise not so much
Excuse ME, I'm MORE than aware of what they are and I DON'T read science fiction.
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Star trek ftw!
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Let me guess... (Score:4, Funny)
And in 50 years, the US Post Office will still be using said technology, while FedEx is traversing through worm holes.
Comment removed (Score:5, Funny)
Re:Let me guess... (Score:5, Funny)
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All while DHL keeps screwing up and sending your package directly to me, and when I send it back they boomerang it right back to me again!
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That's FedEx where I live. They dropped someone else's package on my front doorstep, and I called them to come get it three times over two months before I took it back myself. By the time I got home, their truck is in my driveway trying to drop that same damn package on my doorstep again!
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while FedEx is traversing through worm holes
Oh great! So FedEx will now tell me that my package was delivered. The bad news: it was delivered to me in an alternate reality. With my signature to prove it no doubt. Never mind the fact that "I" didn't get the damn package.
No, it will deliver the package back in the future. Why does everything have to be Trek?
Re:Let me guess... (Score:4, Funny)
Yes, walk outside tomorrow, and get a crapload of packages from yourself from the future, with a note "store these for me, k?" Maybe some UPS discount if they can deliver the package "anytime", cutting down on the number of stops they have to make. You know, saving money and all. Meanwhile, you're getting all these random packages for yourself 20 years from now.
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and then the kids will all start saying 'that's so next week' when they get 1,239 packages that they ordered over 56.4 years, and they come in a courtesy semi trailer, ordered by date of opening them!
but what happens, when a scientist takes advantage of this service, and sends himself everything he patented over his 120 year life span ,courtesy of his life extension drugs he sent himself before he patented them, marketed them and became the first googlbillionaire for having every technology advance for the
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I thought it Fedex would be forced to turn the package over to the frelling Peacekeepers and Chriton would have to go in with Moia to recover it. Shows to go what I know, doesn't it?
Re:Let me guess... (Score:4, Funny)
Its the first of its kind. (Score:5, Funny)
You use this phrase Its the first of its kind. I do not think you know what it means.
And yes .. welcome to /. etc etc
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Yet a previous attempt blew up. .. welcome to /. etc etc
You use this phrase Its the first of its kind. I do not think you know what it means.
And yes
When writing a slashdot post, I try to be succinct.
I figure those (few) who rtfas will sort it out.
It would be the first solar sail successfully deployed. The planetary society one did not blow up; the rocket that would have deployed it blew up, so it never launched.
I'm using these terms somewhat arbitrarily, what would expect from an aardvark?
I'm new here: arbi
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"The first of its kind that hasn't failed already"
Name suggestion (Score:2)
Bajoran-One (ST:DS9 reference).
Interesting (Score:2, Interesting)
Still, the idea of a science-fiction object being realized in the real world is mighty interesting.
Maybe tomorrow they will think about warp drives.
Not science fiction in origin (Score:2)
Actually, the idea was first proposed by Johannes Kepler in the 17th century. And there are still a lot of basic misconceptions about solar sails and light sails, no doubt because of the word "sail".
Simply put, they don't derive their thrust from the solar wind, the stream of charged particles emitted by the sun, but from the radiation pressure of sunlight (as stated in the summary), which provides vastly grea
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The hard part is creating the antimatter. By the way, for warp drives we need something more exotic than antimatter. Matter with negative mass or something.
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Even if we could make antimatter cheaply and on a large scale it still isn't very practical for interstellar travel. The distances are just so unimaginably immense. There isn't yet even a theoretical substance that could propel us to the stars within a human lifetime and then have enough "fuel" to slow down again. Surely everyone has read that NASA "warp drive when" link by now. I'm getting tired of posting it. The idea is that we really need a true "space drive" for practical interstellar travel. Rocket te
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Duh, you just build a machine that creates a complete copy of yourself at the destination in 10 million years from now when it gets there. the plus side, is you don't even need enough fuel except to decelerate the device when it gets there.
as long as you can make a reliable computing device, capable of cloning yourself at the destination, complete with memories, oh an maybe give it enough fuel to come back, make a third clone of you with both the original memories, and the memories of visiting there, and t
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oh wait, i just thought of a problem...
the exponential gravity well problem.
the problem is that while attemting to hit the 'event horizion' of the gravitational effects of the next solar system, you're faces with exponential gravity drag. eg: for every meter you travel, your distance is slowed, based on your toal distance from the sun, and the percentage of gravity well pulling you back, since gravity wells extend to infinity and the next neared gravity well is 2 light years away, you need continuous thrus
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Actually, it doesn't. I remember a program item back at LACon II in '84 where Dr. Forward had something to say about exactly that. He said that recent calculations had shown that if you dropped a lump of anti-matter on the floor it would sizzle like a drop of water in a hot frying pan taking several minutes to vanish. You see, the reaction only takes place on the surface and, of course, the bigger the piece, the less of it is surfac
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Very good point. Another is that modern containment of antimatter is often done by freezing. The closer you get it to absolute zero, the less interaction there is with normal matter.
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What do you store antimatter in if it explodes on contact with matter?
Antimatter containment fields... DUH!
Sheesh, it's like Geordie taught you NOTHING.
Beating against the solar wind? (Score:5, Interesting)
Re:Beating against the solar wind? (Score:4, Informative)
Or am i missing something?
Gravity.
Disclaimer: Won't work if you accelerate beyond escape velocity.
Re:Beating against the solar wind? (Score:5, Informative)
No, that's incorrect. In space travel, the vehicle is in some orbit, and in the absence of a force other than gravity, it's just going to continue in that (typically elliptical) orbit forever. Say you're going to Mars, for instance. You needed to match orbits with Mars, which means you're in the same nearly circualr orbit around the sun that Mars is in. (Of course you also have to insert yourself into orbit around Mars, and get yourself out of that orbit as well, but let's not worry about that for now.) Once you're ready to leave, you don't just wait for the sun's gravity to pull you downhill back to Earth. You're in a circular orbit whose radius is greater than that of the Earth's orbit, so you're not coming back toward the sun unless you can reduce your velocity.
To understand how you'd really use a solar sail, let's start with the case where you just want to increase your distance from the sun. Intuitively, you'd think that you'd just orient the sail perpendicular to the sun's rays, and let it thrust you outward. However, that doesn't work, because the thrust from the sunlight is orders of magnitude less than the sun's gravitational force. Doing that would be sort of like dialing down the strength of the sun's gravity by some tiny percentage, which would alter your orbit for a given velocity vector, but only by a tiny amount.
What you actually do is to point your sail at an angle. The sunlight's thrust then has both a radial component and a tangential component. The tangential component does mechanical work [lightandmatter.com], because it operates in the same direction as the motion of the vehicle. That means it increases the vehicle's kinetic energy. The higher-energy orbit takes you farther out away from the sun.
When you want to come back, you do something similar, but you tilt the sail the opposite way. The tangential component is now in the opposite direction compared to your motion, so it does negative work, reducing your kinetic energy.
This web page [lightandmatter.com] has an example that calculates the optimal angle to tilt the sail at.
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So the sailing analogy breaks down pretty fast. Too bad we can't just stick some kind of fin into the aether.
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and mount lasers on it. you forgot the lasers, that was a shark fin right, you didn't specify!
Maybe it's not just bad car analogies... (Score:2)
Sail_______/
Velocity___}
Force_____}
Sun_______*
In this example, the force on the sail from the solar wind continually increases the velocity of the ship, slowly increasing its orbital radius.
Sail_______\
Velocity____}
Force______{
Sun_______*
In this case, the force on the sail is working against the vector of the sh
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Learned to sail in a HobieCat. They have daggerboards that can be dropped but, in truth, they're not all that good at sailing close to the wind.
They can be tricky to tack, too--you have to make great, wide turns or do what's called wear, when you make a sort of loop at each tack in order to keep the wind astern. If you make the same sort of quick turn you would make in a monohulled boat, you might find yourself dead in the water.
Re:Beating against the solar wind? (Score:4, Interesting)
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As to the hobies, take a look at the smaller older ones. They had no dagger boards. Their outer edge was straight down and the inner edge curve to meet it. Think of the bottom of the "d". It worked well for them.
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Tilt the sail. In one direction, it will increase your tangential velocity, and raise your orbit. In another direction, it will decrease your tangential velocity, and lower your orbit.
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Rail Sail (Score:5, Interesting)
I'd like to see a maglev train on an Andean mountain firing a ship into Earth orbit, which then deploys solar sails to catch the much more plentiful direct solar radiation to accelerate it away from the Earth. That seems like a better way to use the infrastructure we have on Earth, where at least 25-30% of the solar power is lost in the atmosphere and the air creates drag on the accelerated ship, and to use the microgravity and vacuum of space where it's easier to deploy light, flimsy solar collectors in the full sunlight.
Skip it (Score:2)
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"until japan showed that there is a lot of uranium up there. That makes it very different. That gives us power to build and launch Giant Robotic mecha"
fixed that for you, there is also a lot of titanium, to make the giant robots out of.
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How about one of these:
http://en.wikipedia.org/wiki/Launch_loop [wikipedia.org]
It seems plausible. Especially if you look at using Al or CU loops in dyneema as diamagnets rather than iron as a ferromagnet.
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Momentum. Think of a lasso.
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A lasso has a lot of energy put into it with every turn the tail end is pulled. Enough to push the whole lasso up. The lasso stays in place because of the gyroscopic motion around a center of gravity. That rail hump shows neither of those dynamics.
Planetary Society's solar sail (Score:4, Informative)
Boost laser time (Score:2, Funny)
Yep, we'd best start working on the boost lasers, they'd be handy for the 1st Kzin war too.
Where's the keel on a solar sail-powered ship? (Score:2, Insightful)
Cue Light Sailor by Wendy Carlos (Score:2)
And now you'll have two renegade programs running all over the system in a stolen simulation.
End of line.
Sure. Next article (Score:4, Insightful)
> It will travel to space onboard a SpaceX Falcon 1 rocket
Good luck with that one. They can't even get any time on the island because they have to beg & steal for government launch facilities.
A bit disappointing that the space station isn't being used for breathrough research like this. Instead it's busy enough keeping itself alive & selling Buzz lightyear promos.
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They must be doing something right, cause apparently, the rocket is on the pad right now going through dress rehearsals.
clickenzie here. [spacex.com]
Voyage To Infinity? (Score:2)
On the cruise you will have peace of mind with a garden reeked of love.
For the sake of earnest unity on this voyage to infinity.
On the voyage to infinity, can't forget to take your soul.
Cause at the port you'll find no double sign.
Solar Sailing (Score:2)
"They are well known to science fiction readers, otherwise not so much."
They are well known to those familiar with space history. We learned how to build these sails from Echo 1A and Echo 2, launched back in the 60s. Both were aluminized mylar balloons, used as passive microwave reflecting communications satellites. Both were "blown" off orbit by solar pressure. Analysis of the orbital data told us the why and the how much, so now we can do it accurately.
As for "a previous attempt blew up", the same thing h
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Re:I wonder... (Score:4, Interesting)
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Any idea what solar radiation pressure is at, say, 1 AU? I would imagine that it does an inverse-square drop-off as the distance increases, neglecting CME's and other transients.
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Re:cool cool (Score:5, Insightful)
Probably interesting to watch, but something of a waste. The moon's close enough we could study an area carefully (for minerals and features and other details), then when we know it's composition well, we put a nuke up there, and we'll get much more helpful information about it, as well as be able to select the damage threshold more exactly. Less variation in the results is better, correct?
Roughly speaking, a 220lb spacecraft at a million miles an hour would be 6-1/2 kilotons, about 1/2 the energy of Hiroshima, except of course, it would distribute that energy directly into the ground, not in an air burst. It wouldn't even make the news, from an earthquake point of view, they're measured in thousands of megatons. To eyeball it, take a look at "Minor Scale", it's a little smaller, 4.8 ktons, but wikipedias got a decent picture of the detonation. http://en.wikipedia.org/wiki/Minor_Scale [wikipedia.org]
My guess is the moon probably still gets impacts like this on occasion, so wasting a spacecraft might be redundant.
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That's what I would have thought, but according to Wikipedia, [wikipedia.org] when the wreck of the Kielce was being salvaged in the English Channel near Folkestone, the roughly 3,000 tones of HE it was carrying detonated, causing an earthquake measured at 4.5 on the Richter scale.
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I have to take exception with that statement. They never measured anything from the explosion of the Kielce - they merely guess NOW that it was roughly equivalent to an earthquake measuring 4.5. Who knows how accurate that guess is. Second, the Richter scale is a log10 scale, so every step up the ladder is 10 times the force.
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Re:cool cool (Score:4, Informative)
Only problem with that being that a million miles a second is roughly five times the speed of light. Last time I heard, it's not possible go that fast.
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give the man a break, google calculator defaults to saying "299 792 458 m / s" the m being 'meters' but miles is also designated with an m.
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IRC, the quantum entanglement phenomenon has been shown not to transfer information faster than the speed of light. There's no teleportation of matter occurring at all, simply matter here and matter there whose state is coupled. Not at all the same thing.
Einstein showed that there is no need for a static background. Your arguments suggest that light propagates only as a wave, which again, Einstein showed to be false in those same 1905 papers (quanta of light). He didn't write the book until a few years