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NASA to Launch Solar Sail

Posted by timothy on from the cue-bad-brains dept.

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.

42 of 147 comments (clear)

  1. Ah, sigh by Gewalt · · Score: 4, Funny

    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...

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    1. Re:Ah, sigh by ScrewMaster · · Score: 4, Insightful

      Yeah well, Hollywood and science haven't ever mixed well, for the most part.

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    2. Re:Ah, sigh by Anonymous Coward · · 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.

    3. Re:Ah, sigh by neokushan · · 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.

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    4. Re:Ah, sigh by Plazmid · · Score: 3, Interesting

      What do you mean? Wood has strength to weight ratio similar to that of carbon fiber, however wood is much cheap than carbon fiber. The main reason wood isn't used to build spacecraft is that wood is porous, but this might be solved by vacuum coating the wood with aluminum.

    5. Re:Ah, sigh by Iron+Condor · · 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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    6. Re:Ah, sigh by Anonymous Coward · · Score: 2, Funny

      Funny, that's how you get from Bajor to Cardassia as well.

    7. Re:Ah, sigh by Kjella · · Score: 3, 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...

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    8. Re:Ah, sigh by ricegf · · Score: 4, Interesting

      In the book "The Trouble with Tribbles", David Gerrold mentioned that an early Star Trek script included three pages of technically accurate dialog between the Good Captain and his crew to get the Enterprise turned to head to the newest monster-of-the-week. Gene Roddenberry scratched out all three pages and replaced it with a single Captain Kirk command: "Turn around!"

    9. Re:Ah, sigh by sconeu · · Score: 3, Informative

      Almost right. The revised version of 3 pages of technobabble became "Reverse Course!", not "Turn around!'

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    10. Re:Ah, sigh by sconeu · · Score: 3, 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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    11. Re:Ah, sigh by slashtivus · · Score: 2, Informative

      Solar sails are nothing but gossamer (light weight) sails. If it was that easy to get something like that to generate electricity with something as thin as standard garbage-bag plastic I'm sure we would have done it before. Solar panels are pretty much a similar process related to CPU/microchip fab == silicon chip == expensive and heavy.

    12. Re:Ah, sigh by CrimsonAvenger · · Score: 4, Interesting

      Solar sails are nothing but gossamer (light weight) sails. If it was that easy to get something like that to generate electricity with something as thin as standard garbage-bag plastic I'm sure we would have done it before. Solar panels are pretty much a similar process related to CPU/microchip fab == silicon chip == expensive and heavy.

      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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    13. Re:Ah, sigh by Mike610544 · · Score: 2, Insightful

      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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  2. What a stupid generalisation! by neokushan · · Score: 3, 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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    1. Re:What a stupid generalisation! by oodaloop · · Score: 2, Insightful

      Obviously they weren't aware that one data point nullifies a generalization. Stupid indeed.

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  3. Let me guess... by Anonymous Coward · · Score: 4, Funny

    And in 50 years, the US Post Office will still be using said technology, while FedEx is traversing through worm holes.

    1. Re:Let me guess... by DigiShaman · · Score: 5, Funny

      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.

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    2. Re:Let me guess... by Anonymous Coward · · Score: 5, Funny

      Meanwhile, UPS will just launch the damn thing into a black hole and say customer service is 'working on it.'

    3. Re:Let me guess... by canuck57 · · Score: 2, Funny

      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?

    4. Re:Let me guess... by st1d · · Score: 3, 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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    5. Re:Let me guess... by aplusjimages · · Score: 3, Funny

      How do you think your alternate reality self feels? Now he's stuck with the "Hungry Bitches" DVD you ordered.

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  4. Its the first of its kind. by OzPeter · · Score: 4, Funny
    Yet a previous attempt blew up.

    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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    1. Re:Its the first of its kind. by hvm2hvm · · Score: 2, Insightful

      Well thanks captain obvious. But if they meant that they should have said that. "The first of its kind"<>"The first of its kind that didn't blew up". Also, might I add that it didn't blew up because it hasn't been launched yet? And yeah, it could have meant that its the first kind (like in model) of its kind or something like that. Yeah, this is slashdot so I'm kinda used to that.

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  5. Interesting by KasperMeerts · · Score: 2, Interesting

    I hope my grandkids can one day go outside to take a spin around Mars with their solar sails.
    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.

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    1. Re:Interesting by KasperMeerts · · Score: 2, Informative

      That's the easy part. A couple of electric and magnetic fields and it'll work out.

      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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    2. Re:Interesting by 0111+1110 · · Score: 2, Insightful

      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 technology regardless of the fuel just isn't going to do it.

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  6. Beating against the solar wind? by DerMatsi · · Score: 5, Interesting

    From TFA: "And like a marine sail, a solar sail could also bring you home. You could use the solar sail to tack your vessel, making it travel "against the wind," back to Earth." I don't see how this would be possible.. sailboats can do this because of a keel which exerts force on the water, which cannot be done in the near vacuum of space. Or am i missing something?

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    1. Re:Beating against the solar wind? by amorsen · · Score: 3, Informative

      Or am i missing something?

      Gravity.

      Disclaimer: Won't work if you accelerate beyond escape velocity.

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    2. Re:Beating against the solar wind? by bcrowell · · Score: 5, Informative

      Gravity.

      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, 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 has an example that calculates the optimal angle to tilt the sail at.

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    3. Re:Beating against the solar wind? by Phanatic1a · · Score: 2, Informative


      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.

    4. Re:Beating against the solar wind? by techno-vampire · · Score: 3, Interesting

      AIUI, wearing and tacking are two separate ways to change course across the wind. In tacking, you turn your ship across the wind, using the ship's momentum to keep you going until your sails can catch the wind. (If you fail, your ship is said to be "in irons," pointing directly into the wind with no forward motion.) Wearing ship is much easier but, as you note, takes more room. You turn away from the wind going all the way around in a big turn and emd up with the wind on the other side of your ship. Although it's slower, it does have the advantage of avoiding any chance of getting stuck.

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  7. Rail Sail by Doc+Ruby · · Score: 4, 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.

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  8. Re:I wonder... by bob.appleyard · · Score: 2, Interesting

    Says it uses "photon pressure," so just under c would be the cut-off, I reckon. It would probably leave the solar system long before it reached that velocity, though.

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  9. Planetary Society's solar sail by imipak · · Score: 3, Informative

    Still time to chip in your contribution towards the Planetary Society's second attempt to do a working solar sail.

  10. Boost laser time by CBob · · Score: 2, Funny

    Yep, we'd best start working on the boost lasers, they'd be handy for the 1st Kzin war too.

  11. Where's the keel on a solar sail-powered ship? by davidkhuffman · · Score: 2, Insightful

    The Physorg article notes: "And like a marine sail, a solar sail could also bring you home. You could use the solar sail to tack your vessel, making it travel "against the wind," back to Earth." But, I thought that do sail across the wind you need something to provide "lift" to counter the lateral force of the sail, which is provided in boats by a keel, or centerboard, or daggerboard, or a fin and rail on a windsurfer, or a skeg, etc. etc. Where's the counterforce in a solar sail in space?

  12. Re:I wonder... by Orange+Crush · · Score: 3, Interesting

    A solar sail craft's maximum speed will be considerably less than c. Mass-to-sail ratio and diminishing radiation pressure as the craft travels further from its star will be the biggest limiting factors.

  13. Re:cool cool by st1d · · Score: 4, 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

    My guess is the moon probably still gets impacts like this on occasion, so wasting a spacecraft might be redundant.

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  14. my parents by Anonymous Coward · · Score: 4, Funny

    My parents were married, you insensitive clod!

  15. Re:cool cool by gyrogeerloose · · Score: 3, Informative

    hopefully it will accelerate to a reasonable speed of a million miles a second

    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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  16. Sure. Next article by heroine · · Score: 3, 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.