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The Flight of the Solar Sail
N3wsByt3 writes "After months of uncertainty, the final verdict has fallen: The Planetary Society has reveiled that it will launch its Cosmos 1 on June 21. Cosmos 1 will be the first non-governmental spaceship that makes use of solar sails as main propulsion mechanism - it is pushed along by light particles from the Sun, instead of bringing its fuel along for the ride - which makes this a unique experiment in more then one way." This was supposed to have happened already, so here's hoping things get off the ground this time.
more THAN one way
"reveiled:" is that like the opposite of "unveiled?" So, are you saying that they have tried to cover up the news? And if so, then how are we finding out? Or is it from the French "reveil:" the awakening. Did they wake up to the news? Is that why they tried to cover it up?
So confused.
If you open yourself to the foo, You and foo become one.
http://ntl.matrix.com.br/pfilho/html/lyrics/o/orin oco_flow.txt
"ORINOCO FLOW (SAIL AWAY)
Enya
Let me sail, let me sail, let the Orinoco flow,
Let me reach, let me beach on the shores of Tripoli.
Let me sail, let me sail, let me crash upon your shore,
Let me reach, let me beach far beyond the Yellow Sea.
From Bissau to Palau - in the shade of Avalon,
From Fiji to Tiree and the Isles of Ebony,
From Peru to Cebu hear the power of Babylon,
From Bali to Cali - far beneath the Coral Sea.
From the North to the South, Ebudae into Khartoum,
From the deep sea of Clouds to the island of the moon,
Carry me on the waves to the lands I've never been,
Carry me on the waves to the lands I've never seen.
We can sail, we can sail...
We can steer, we can near with Rob Dickins at the wheel,
We can sigh, say goodbye Ross and his dependencies
We can sail, we can sail..."
all the governmental solar sail spacecraft? WTF?
This article made me wonder when was the last time the .gov used solar sails... I couldn't remember any (I am not that much of a space guy). So I decided to look up "solar sail" on Google. The first link that came up... planetary.org I have never heard of the site before (almost makes me wonder if it is fake) so I got to thinking... could slashdot have upped the ranks of that website on google? Could this be a newly found slashdot effect?
/dev/null
Please direct all flames to
This solar sail is really going to blow.
Honestly the idea that because it doesn't carry fuel makes it easy to 'travel to the stars' is kinda stupid. For one thing, almost by definition you can't travel towards a star on this thing because as you approach it, it will start to slow down, and eventually stop.
The idea of using the suns energy is good, but maybe they should find a way to harness that energy so one could move the direction one pleases.
"A man is but the product of his thoughts what he thinks, he becomes." -Mahatma Gandhi
generated by the beans of the universe
So.. uhh.. speed? I haven't RTFA but I guess the question would be, why. What is the voyager probe propelled by, that's just rockets to correct trajectory and drift, no? Why solar sail, when a probe can reach the edge of our solar system the running out of fuel problem when reaching long distances is solved so.. is the solar sail fast? (over a very long time allowing acceleration like an ion drive that is).
Spelign onluy cvoutsn ni commadns, config s,adn cod e,not inc hat. Adn nto inS lasdhot sotries iether, its eems. ~.^
It must be Windows. It needs half a gig of RAM and a hardware-accelerated graphics card just to run Solitaire.
Lesbian Seagull...
Uhhh... Would that be Johnathan Lesbian Seagull?
Spelling is fine, it should be "grammar police" instead!
"You mortals are so obtuse." -Q
You could use a solar sail to go from Earth to Mercury if you wanted.
Angle it so that thrust is opposite the orbital motion of the earth. You slow down relative to the sun. You fall to a lower orbit. Nifty, huh?
If you're really in a hurry to slow down you detach a reflector, let it fly in front of you, and have a planet-based launching laser fire at the reflector, bounce back to you and slow you down.
The second one: Johnathan Lesbian Sequel
so apparantly we have the technology to propel objects via sunlight... but we still cant make our cars to utilize a resource besides gasoline ( with a little hydrogen somestimes)?
Something tells me Styks could make a comeback off this launch: I'm Solar Sailing Away
fly with me, FLY!
with MIND bullets! that's telekinesis, kyle.
ok, fine. i think it's crap and they should focus on nuclear propulsion rather than some crappy-ass crap sail that's gonna take a gillion years just to get to a point where it can send useful information because it goes so slow. crapping crap crap
We know the Voyager probes took 30 years to reach the edge of the solar, give or take a few stops to snap pictures at some of the more famous landmarks. But how long would it take the solar sails to reach the edge (assuming that it was making a beeline out of the system)?
:P
In laymen terms, please. For us dumb Americans.
Most discussions about solar sails tend to discuss things like interplanetary or interstellar travel. While this is cool, it is a rather long term goal. The more interesting uses would be orbital stationkeeping. Currently, if you want a geostationary orbit, you either have to set the satellite at 41,000km orbit. If you want it at a different altitude (this is a 200ms round trip lag for light signals) you have to constantly burn fuel to remain geostationary. Once we have viable solar sails, they would be useful to maintain geostationary orbits at various altitudes without burning extra fuel. You just have to make sure that the satellite doesn't fall down in the night.
You could also use solar sails for other stationkeeping like the L1,L2, & L3 Lagrange points which is needed for certain telescopes.
WTF? Where is the other post that mentions a lesbian seagull? And how can the very first post be redundant?
A solar sail could, theoretically, pass the Voyagers in less than a week. That's the advantage of having continuous thrust along the way, rather than one impulse at the start and then coasting as the Voyagers did.
The Voyagers are now at a distance of about 13 light-hours from the sun. A thin and lightweight solar sail would quickly accelerate to almost the speed of light, so it's possible to cover that distance in a few days at most.
If this is true, why aren't we sending a probe to Pluto, or Alpha Centauri, for that matter?
What's the secret drawback that you're not mentioning thats preventing this from being used?
To confirm you're not a script, please piss in my ear.
The problem with the parent's post is the sail itself. Our solar system is a rocky and dangerous space, and so far, we have no idea what the area outside of it is like either.
The sail would quickly break apart as it gets struck by all kinds of space debris, some left by us, others by more natural occurances. Thus, for an effective craft, multiple sails would be kept on board, being deployed stratigically when the previous sails are no longer providing maximal thrust, and when the coast is clear.
Next, between those times when the sails are not up, the ship will probably want to keep thrust, so it will have to carry onboard some propellant to keep its thrust up during the times it is without sails. Thus, the ship will lose a significant portion of weight during its travel.
Lastly, unless we align everything like we did with the Voyager launches, gravity will not be so forth coming for this space craft. This will probably mean multiple near-sun passes to build up the speed nessicary to exit the solar system and continue on to the next star. This means some clever routing by computer simulations, along with a computer figuring when to discard and open new sails along the way.
Not only will all of this cost a lot, it will likely make it take much longer to get out of the solar system. Lucky for us, as we can pile on the goodies like cameras, radio antenna, and do some exploration as it passes through the planets building up gravitational accelleration.
"Victory means exit strategy, and it's important for the President to explain to us what the exit strategy is." G.W.Bush
So what happens when it gets close to another star? If the Sun will push it now, the next star will push it too I would assume - but which way? The sail could go backwards, wrap around what its pulling, and then due to momentum you have a giant missle.
The fact that such a solar sail wouldn't be able to carry much of a payload.
OK, here's the long answer: a solar sail made of a reflective membrane a few atoms thick would be able to accelerate very quickly to high speeds. But if you attach any sort of payload to that membrane, then you have to accelerate the mass of the payload as well as the solar sail itself.
There's a technology limit here, the bigger and thinner we can make a sail with a given strength, the quicker we can send a load to anywhere. Since no one ever used a solar sail for propelling any payload, we do not have real data to answer precisely the question of how long it would take.
Assuming a technology level we can reach within the next ten years, I would guess we could build a solar sail scientific spacecraft with roughly the same capacity of a Voyager, capable of reaching Pluto in a year of travel.
For furhter reading, there's an interesting anthology about solar sails, published in 1990 with Arthur Clarke and David Brin as editors. The title is "Project Solar Sail" and it has both science fact articles and fiction short stories.
And there are practical solar vehcles that run off of batteries charged by sunlight -- range is around 170 miles between charges, and a full charge takes 45 minutes to one hour (charging from the wall takes less time).
http://www.solarvehicles.org/pages/1/index.htm
Okay, I understand that something can be pushed by light. This makes sense. Yet I came up with what I consider to be a paradox. Can someone find the hole in my logic and help me understand things better?
Okay... I have two solar sails with perfect reflecting ability. I place them so that they are facing away from each other. I turn on my handy-dandy perfectly unidirectional light source so it hits one of the sails square on.
Bounce! The light pushes the sail a bit. Light reflects to other sail. Bounce. The light pushes the sail a bit. Light reflects to other sial. Bounce.
I don't see how the light beam loses any energy in my model. Yet the sails definitely gain energy. Can someone show me the flaw in my logic?
Thanks!
See my journal for slashdot ID's by year. Mine created in 2005. http://slashdot.org/journal/289875/slashdot-ids-by-year
This was supposed to have happened already, so here's hoping things get off the ground this time.
/oblig
And preferably the ship!
how ill is that???? look here to see what i'm saying: http://www.planetary.org/cometbash.html
Second reply to this post. I did some math, to show how naive the parent post is:
.000454N/(10kg) = 0.000045365 _m/_s^2
Assume 10Kg craft.
F = (S*A*sin(theta) / c
Theta = incident angle
A = area
S = solar flux
Let theta = 0, A = 100m^2, S = 1.36KW/m^2
F = 0.000454 N
a = F/m =
22043.6 Seconds to reach 1 meter per second (6.12 hours)
So about 6 hr/(m/s)*4500(m/s)(about that needed to get to mars on a nice, almost hohmann, orbit from earth orbit). = 1125 days.
Presently we can get to mars in about 180 days.
V_esc for sun at earths orbit:
M_sol = 2E30 kg,
R_eo = 1_Au = 1.496E8 km
G = gravitational constant = 6.6726E-11m^3/(kg*s^2)
V_esc = root(2G*M/R) = root(2*G*M_sol/R_eo) = 42.239 km/s
Add to that the velocity to seperate the crafts orbit from earths: ~3km/s = ~45km/s
Using a straight shot, which is completely 100% impossible, it would take 6.12hrs/(m/s) * 45000 m/s = 31 years, 315 days. Even.
The reason a straight shot wouldn't work is that flux falls off as the square of distance. So you would need to integrate over time to obtain your velocity, with an inner equation dependant position, which is dependant on your velocity, which is dependant on your past acceleration, which is dependant on your past position... you get the idea.
dependent. Not dependant. sheesh. like 5 times too.
...and a star to sail her by.
Is this thing pushed by solar wind or photons?
"The use-mention distinction" is not "enforced here."
While I think that solar sails are a neat technology, I would like to hear what some other people here think of their potential as manned spacecraft.
My contention of what I've seen from all of the numbers that get used to describe velocities and transit times for solar sails, is that this will be used primarily for transfer of bulk goods between different places in space.
A comparison would be how bulk goods are shipped today in industrial countries. Right now the most common methods are by barge (or equivalent ocean ships like oil tankers) or by rail, and slow-moving rail at that. It doesn't have to get there immediately, the stuff simply has to get there eventually, and as cheap as possible, at least on a price/kg basis.
In space a bulk shipping service would be even more crucial. Passenger traffic would have to be done on much faster ships, and IMHO the only reliable energy source with the density needed to accomplish that sort of travel (i.e. Earth to Mars in 3-4 weeks) is nuclear propulsion. Chemical rockets simply don't have the energy needed to get us anywhere... at least in any sort of hurry.
While a neat technology, and necessary to the opening of the solar system to mankind, this technology will be a more workhorse technology rather than something "sexy" that some cool people will want to get to put on their "space yacht". A 1 GW reactor that can push your ship at a continuous 2 G acceleration for 7 weeks on the other hand....