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Solar Sails
carpediem55 writes "Reuters is reporting that The Planetary Society (founded by Carl Sagan) is bringing science fiction to life, with a Solar Sail powered by light." But get how they plan to launch it: on a Russian submarine ICBM. The sponsors have a site with more information.
This propulsion technology is obviously not intended to be the sole means to move a vehicle from one location to another. But it is very efficient in long-distance travel.
Just because you have a solar sail to propel you from location A to location B, doesn't mean you cannot also have some sort of fuel based thruster device to maneuver your vehicle at the local space-station dock or whatever.
-=e
While that's all well and good, I couldn't care less if a pseudo-me sees the wonders of the universe. I will still be stuck on this little ball with nothing to do but pust on Slashdot.
Seriously, I have the same ideological problem with the transporters on Star Trek. I cease to exist while my doppleganger continues to live my life, play with my kids, etc. I mean, I have nothing against potential digital clones of myself- I'm sure we'd get along well- but I would receive no benefit whatsoever from the donation of my neural patterns.
Dewey, what part of this looks like authorities should be involved?
> Although facinating to consider, it seems that a solar sail would be of limited use for a two way trip. A solar sail powered spacecraft can't tack against the 'wind' like a sail boat on the ocean is able to do.
s /i ntro/tacking.html
Actually it can, sort of, since the sun's gravity acts in the opposite direction to the solar wind and your ship is going to be in orbit about the sun, by angling the sails appropriately you can move to a closer orbit, as well as a more distant one.
http://www.ugcs.caltech.edu/~diedrich/solarsail
If you are using an interstellar solar sails, possibly read "destination star" for "sun" at the far end - alternatively see
http://www.forwardunlimited.com/pdf/tp069.pdf "Roundtrip Interstellar Travel using Laser Pushed Lightsails" (yes, you can use an Earth based laser for the return journey, and you don't have to tack into it).
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rant
Well I'm not terribly into astronomy, so I don't follow sattelite launches much. I have no idea why launching from a submarine would be desirable, so yes, I find it curious. Maybe because there simply are more ICBMs that are available to the public in subs than on land (if any), but everything else being equal, it seems to me, that costs should be lower on land than from a submarine.
The first U. S. satellite was launched from a converted ICBM -- the Redstone booster.
People always forget about those other two guys... kinda like Apollo 11. Everyone remembers Neil Armstrong, some people remember Buzz Aldrin (probably because he has a cool name), but who remembers Michael Collins?
Your reply illuminates the presumption that anything unconquered is by definition "disorder". This is exactly what I'm talking about. "Discovery and learning" does not necessarily equal conquering and vice versa.
Generally the mindest of "Western civilization".
"fatalism:
1.The doctrine that all events are predetermined by fate and are therefore unalterable.
2.Acceptance of the belief that all events are predetermined and inevitable."
Yup, things sort of suck when one's whole world-view revolves around the belief that humanity is an imperfect creation, that nothing really worthwhile in this world can be done, except to work hard and resignedly hope for a better afterlife. A subconscious drive for some abstract concept of "progress", coupled with an ultimate resignation, I think leads us to strive very hard without purpose, exploiting for immediate gain. What shall we "conquer" after space?
"I guess what I'm really asking is what do you have against Western thought?"
Besides the dogged persistence to always want to conquer some new thing for the holy grail of some undefined "progress", nothing really. But I'm sure I can always be assured of some knee jerks in the Slashdot crowd. (Sober introspection about our mad rush to develop and conquer? What you say?!)
It's 10 PM. Do you know if you're un-American?
well, slow accellerating might be more the ticket. Keep in mind that it is perfectly feasable to concentrate and redirect the sunlight, and also to capture the reflected photons for use as energy (perhaps to power a hydrogen scoop and thruster)?
For better interplanetary missions, I read the really enjoyable Web between Worlds by Sheffield. He toys with the idea of space rotors (I think Forward wrote about these as well) which basically store ALOT of angular momentum. You jump on in the middle and lower your way out on a rotor. By the time you're at the end, you're up to speed and just let go when you are pointing in the right direction.
Both Velocity and acceleration at the tip are linear in radius, but Acceleration is quadratic in rotation while Velocity is linear, so by doubling arm length and reducing rotation speed by sqrt(2), you maintain a constant acceleration, but increase outgoing velocity by sqrt(2). Tensile requirements go up linerally by radius (it's longer, but acceleration is constant) so the material requirements are not too stringent.
The one caveat is that you have to catch as much as you throw or else inject energy into the rotor some other way.
Can you think of anything better for them to do with all of they money they have? I imagine most of them have been down the 'feed the hungry' path before, probably done the 'cure a major disease' thing too, so why not 'spread humanity to the stars' as this months charity event?
Kintanon
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Very cool story -- even though I won't move solar sails from my "Vaporware" until I actually see one in outer space...
The right to offend is far more important than the right not to be offended. (Rowan Atkinson)
- Our current probes are already slow. They are limited by the kick that chemical-fuel boosters can give them, and then have to coast or run complicated gravity-assist trajectories to get to their targets (does VEEGA mean anything to you?). Solar sails can be much faster.
- We can use solar sails on the missions we are doing now, to get more science out of them. Consider the NEAR mission. This mission is at an end because the NEAR craft is out of fuel. If it had only required fuel for small but rapid changes in velocity and instead relied on a solar sail for cruising thrust, it would be on its way to another rock. And then another, and another.
- Because solar sails can produce thrust without expending any mass on a more or less indefinite basis, they are one of the big enabling technologies for real exploration and colonization of the solar system.
Clear enough? If the sails are laser-propelled, your cargo vessel could be both smaller and faster over long distances than anything which propels itself only with fuel it carries. Even without laser propulsion, the sails have many uses which do not involve hauling people around. These uses include propelling the probes to locate resources or other points of interest, and hauling the supply stockpiles for people to use when they arrive. The cargo travels by slow boat, the people travel by express.--
Knowledge is power
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Study hard
Time is Nature's way of keeping everything from happening at once... the bitch.
This is beyond cool, and I hope this works out. Not only is this a hopeful new technology for space travel, but I get a kick out of how it's being launched from a converted ICBM -
Turning swords into plowshares...boring. How about turning missles into spacecraft. Now that rocks.
And to think, this will be the first. I hope NASA gets off their ass if this works. Typical that something so experimental, hopeful, and daring had to come from private funding and not from NASA.
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ah honey, we're all resplendent - Bill Mallonee
Never ceases to amaze me that people are insisting on physical sails for solar sailing, given that there are a slew of problems to contend with. Furthermore, the mission profile simply calls for a deployment test and minimal motion (no plans for a planetary or extrasolar mission).
Using an M2P2 (Mini-Magenospheric Plasma Propulsion) drive would be a much better choice, because in addition to the lack of launch mass (expensive!), you don't need to worry about deployment problems, and can then think about actually doing some science instead of a publicity stunt. More on M2P2 here and here.
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But you do have to admit he/she is improving. It took a line or two today before it was off topic. :)
Cypherpunks: Civil Liberty Through Complex Mathematics. Those who live by the sword die by the arrow.
It wasn't necessary to prove anything beyond that. An object can't travel at a given speed without first accelerating to that speed (quantum mechanics aside; we're talking about spaceships here).
Oh, for christ's sake, it was a joke. You can't tack into a solar wind anyway, keel or no--the aerodynamic effect that allows sailboats to tack upwind is not a property of the photon breeze that pushes a light sail.
No relation to Happy Monkey
Reading the various accounts it seems clear that the major objective seems to be testing teh deployment of a large, lightweight structure using inflatable tubes. I'm a bit surprised that they aren't aiming for more than a minor boost in orbital attitude from solar pressure.
Still, I've often wondered why there aren't more space installations based on inflatable structures. You could build a collosal laboratory in space out of some sort of plastic sandwich (to make it self-healing from micrometeor hits). A structure larger than a football stadium could fit in the shuttle bay and inflated in orbit. You probably wouldn't want to live in one of them (radiation shielding), but you could certainly do materials science and agricultural experiments in one of them. Heck, you could make a giant inflatable wheel and spin it for "artificial gravity"
But there is another way. Instead of travelling faster, we just need to travel subjectively faster. I anticipate that in 20 years time we will have the technology to upload or mindfs into computers, and send digital proxies to the stars, using solar sail technology.
Of course, the travel time would be thousands of years, but subjectively speaking it would be instantaneous.
As Einstein irrefutably proved that travelling faster than the speed of light is utterly impossible, some sort of adjustment of our subjective timeframes is the only solution to interstellar travel.
When the singularity comes, as predicted by Vernor Vinge, I shall be among the first to upload. That way I shall be at an advantage, and may perhaps be able to ascend to the stars on light sail technology.
Speaking as a transhumanist, I must say that I consider it eminently possible, even probable, that these technologies will develop in the way I have outlined.
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As long as the alternative is to bring huge amounts of fuel and burn it over a short period, you will have a point where it for longer distances will be significantly cheaper to build a solar sail powered ship with a sail large enough to get you to your target in the same amount of time.
And keep in mind that nothing prevents you from for instance using a two stage system, where you do a short, intense burn using a normal engine first, and then deploy the solar sails afterwards to continue acceleration for the remainder of the trip.
I am involved in a space project, and we have selected this same launcher. It simply is the cheapest one around at the moment. The Makeyev corporation (designer and builder of the thing) and/or Russian navy have some 200 (I beleive) decomissioned ones left over since the START-I (or -II) treaty. These missiles have to be destroyed, and the simplest way to do this is by launching them. Then, why not put something useful on it? Note that the original launcher is not capable of launching something into orbit as far ads I know. Here, they use a solid-propellant kick stage to achieve that. And about launching from subs; I'm not quite sure why they do that, probably something political involving the navy, missile ownership and free launch training, buit it has been done before. Some German microsats were launched on a Shtil (a larger version of Volna) from a sub in '98 or '99. A number of suborbital microgravity missions have been flown with this Volna.
I don't believe this is sad at all, nor is it unprecedented. Corporate satellite launches and private science missions are often launched using non-US technology, such as the French Ariane launch system. One major consideration is cost when making these decisions, another is time. Basically if something can be launched for less when it needs to be launched, rather spend more to wait past the optimal window for launch to use domestic equipment, corporate and private launches will always choose cheap (read: not-as-expensive), reliable, and timely alternatives.
As far as using a Russian ICBM, I say go for it. ICBM technology can be well adapted to a low-orbital insertion, and it takes another weapon off the tally of the world. I'm not a pacifist typically, but really, if weapons technology can be put to non-weapons use, lets use it.. its already been tested and doesn't need an extensive engineering process to be feasible.
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I think I'll call this one Bob.
Live with Love for Love is Life. --mine.
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I think I'll call this one Bob.
Live with Love for Love is Life. --mine.
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I'm reminded of The Mote in God's Eye and the poor little Moties trying to escape their planet on a solar sail powered craft.
Although facinating to consider, it seems that a solar sail would be of limited use for a two way trip. A solar sail powered spacecraft can't tack against the 'wind' like a sail boat on the ocean is able to do. However, I find the lack of harmful byproducts to be an appealing advantage for solar sails.
Sailing was the most environmentally healthy way mankind ever developed to traverse large distances, and it seems appropriate that the same techniques be adapted to space travel. I am disturbed when I hear reports of engineers speculating on the construction of atomic weapon powered space craft, or such. We have already despoiled our own planet so utterly; we should keep space in its pristine purity.
This is precisely the sort of work that scientists and engineers should be engaged in. Rather than just asking what we can do, we should ask what we can do cleanly and well, without causing more of an impact to our environment than necessary.
- qpt
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Domine Deus, creator coeli et terrae respice humilitatem nostram.
Normal sized spacecraft in Earth orbit have to correct their position and attitude for the effects of solar pressure, along with other disturbances from gravity gradients and residual atmosphere. The solar influence is usually small, we are talking about micro-Newtons, but because the duration is long, it can have a significant affect. Since the largest component area-wise of most satellites are the solar arrays, which are normally about 20 m x 1 m x 2 (satellites are normally symmetrical to avoid rotational disturbance torques) they only have an area of around 40 m^2, compared to over 700 m^2 for the solar sail proposed. I'd suggest this is more than big enough for a proof-of-concept vehicle!
it's not that practical for planetary travel, or even interplanetary travel
This is exactly what it's good for - the speed builds up extremely slowly (it only has the pressure of the solar wind driving it), and so the further you need to travel the more effective it is.
You need a more maneuvourable (sp?), or faster reacting, engine for that when it comes to landing, emergency procedures, etc.
You certainly do, but that's not what you would use a sail for. They're intended as a replacement for the long slow burn you need to get to your destination, so you don't need to carry a huge mass of fuel just to get there (instead you can save most of it for the final manoeuvres).
-dair
But get how they plan to launch it: on a Russian submarine ICBM.
Why is that particular point made? Because its Russian, or because it's an ICBM? Neither seem overly unusual to me. Russians have a good deal of expertise when it comes to space technology, arguably more so than the US. And using an ICBM kinda makes sense. I believe they've been bandying this idea around for quite a few years.
The tubes wouldn't have to be that strong if only small pressures are used inside of them. Because space is essentially a vacuum, you can use a very low pressure inside the tubes to accomplish the same thing. It's the difference in pressure that matters.
"...Solar Sail powered by light."
Homer: So, they have solar sails powered by light now.
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It seems that this point was made because this is highly unusual:
#1) It is a Russian weapon system.
#2) It uses a submarine as a launch platform. How many satellites get launched from submarines?? That is extremely unusual.
#3) An ICBM is not designed to loft a large-size payload. A set of MIRVs, while very heavy, is relatively compact.
#4) More to the point, an ICBM is not designed to deliver a payload to space. It is designed to deliver a payload to earth. Why do you think that Alan Shepard's flight lasted only 15 minutes? Because he was sitting on top of a Redstone ICBM.
So yes, it is overly unusual.
"Chill, Orrin!"---Trent Lott
Pretty nifty.. But I have a couple of problems/questions..
It says that the sail is only 30m in diameter. I was under the impression (from reading Omni magazine and Larry Niven, admittedly not the most reliable of sources) that one needed a sail of huge (kilometers) size to be able to get a noticeable boost from the solar sails. Also, the article says that they're using inflatable tubes to unfurl/stabilize the sail. IANAP (IANA Physicist) but wouldn't that make those inflatable tubes have to be tremendously strong to be able to survive in the low-pressure environs of space?
Those thoughts aside... It's pretty cool. And I wish I could launch my girlfriends cat out of a goshdarned ICBM tube.
Brant
Brant
Argle. Bargle.
Norad: Umm... We just detected a ICBM launch from the Russian submarine Smirnof.
Kremlin: Not a problem, comrad! Is just launch of solar-sail you may have been reading about on slashdot.
Norad: Okay... Umm... Our projected trajectory puts it landing in Washington, DC.
Kremlin: Is normal! It will separate at high altitude and booster will fire sail into space. Missile will fall harmlessly into Atlantic.
Norad: Okay... Umm... The ICBM appears to have landed in the capitol, exploded, and wiped out our entire government...
Kremlin: Is this a problem, comrad?
Norad: No, not really. Just commenting.
The enemies of Democracy are
But get how they plan to launch it: on a Russian submarine ICBM.
(Jump forward 4 years, under the sea, in a Russian sub.)
Weapons Officer: Missile number five has been launched. That's one small step for man, one giant-
Captain: Gustov! You mean missile number nine, right?
Weapons Officer: Shazbot!
I was fortunate enough to be in Russia several years ago (as part of a NASA contract) and got to meet and work with Professor Vladimir Syromyatnikov, the father of the Solar Sail, who is one of the most gracious and intelligent men I have ever met. He is truly a brilliant mechanical engineer. His genderless docking collar design is a work of poetry in steel.
The good professor was kind enough to invite me up to his apartment one day to talk over lunch and meet his wife and family.
I often think about that afternoon and in particular, one corner of his living room where his television set was placed. There, atop the tv was a VCR and yup, you guessed it, the clock was blinking "12:00". To this day, whenever I need to assess my own failings, I just remind myself "Even Rocket Scientists can't do everything".
You can email the professor at:
vladimir.syromyatnikov@rsce.nasa.ru
"A microprocessor... is a terrible thing to waste." --
"A microprocessor... is a terrible thing to waste." --
GeneralEmergency
Space.com has more on the subject here.
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