Solar Sail Craft Damaged 54
C. Mattix writes "It looks like we won't know if the solar sail will work for a while. There was an accident prior to launch that will delay it for quite some time. Full story from Yahoo."
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Solar Sail Craft Damaged
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If it wasn't for Newton, we wouldn't have to eat bruised apples.
The Russkis broke it (Score:1)
Blockbuster called... (Score:1)
[Philip Michael Kramer ate my balls.]
Re:This is not NASA (Score:1)
If the tether really works via induction, what you could do in principle is to drive it backwards with the power you get from elsewhere (solar cells, plutonium rtv, et al). Then you are effectively creating a magnetic field which pushes against the earth's field and lifts your orbit.
Figures (Score:1)
Re:It's an alien conspiracy (Score:1)
It's an alien conspiracy (Score:2)
C'mon, old news: standard regatta rules apply (Score:2)
sheesh! once again the slashbots dive right in without being familiar with sailing tradition.
Re:Thus... (Score:2)
I suspect the Russians (Score:4)
The Russian space agency must be reeling, now that MIR is out of the sky. They were once a proud nation with a proud space heritage, but now they're a third-world grounded nation begging for international aid from the west. That has to hurt.
So what do they do? They sabbotage America's glorious space program. They're jealous of our potential and they're jealous of our success. They never forgot that we were the first nation in history to successfully fake a moon landing, and they won't forgive us NASA's recent successes with missions to Mars. Worse than that, we insulted their collective genitalia with Taco Bell's publicity stunt which put a target in the Pacific ocean for MIR to land on.
NASA is far too clever to have caused this accident by their own incompetence. America is too strong a nation to let such accidents get in the way of our manifest destiny. We must find the spy who committed this act of terrorist espionage and bring him to justice.
The Cold War is very much alive.
Re: Not hot enough for ya? (Score:2)
conwstruction of a mirror that effectibely focuses this energy into
the space required is another matter addressed elsewhere . . .
>P>
hawk
Re: Not hot enough for ya? (Score:2)
hawk, sticking to what he knows . . .
Re: Not hot enough for ya? (Score:3)
> the square of the distance is it not?
No, it is not.
That is the density for a point source that is radiating in three dimensions. For a lossless focused mirror, the density would be the density at the point of the reflector times the ratio of the area of the reflector to the area of the target. This has to be adjusted for losses at the mirror (less than full reflectivity) and through the air (you hit molecules and disperse, and what's left will be ionizing the air near the target).
hawk, actually a physicicst among his many hats.
Re:I suspect the Russians (Score:1)
NASA is not anywere in a picture.
well at least we now know.. (Score:3)
Re:This is not NASA (Score:2)
They were doing experiments with electricity generation with tethers, and they found that much more electricity was generated than expected. The tether broke, and when they landed they insepected the severed end. It had been burned through by an electric arc, which gives you a good demostration of generating electricity by moving a wire at speed through the earth's magnetic field.
Re:This is not NASA (Score:3)
Re:Good, solar sails are too dangerous to be allow (Score:2)
Before you condem me, think of the facts. They are talking about orbiting a huge, acre sized, piece of mylar, with controls to change it's orientation.
It's a giant space mirror!
For those of you didn't read the Mars trilogy, think back to the first time you played with a magnifying glass in your backyard.
Because far too many people seem to be taking this (hopefully) humorous post seriously:
While you could fry things magnifying-glass style with a concave mirror, you won't be able to with a solar sail. To focus light properly at all, the mirror would have to have a very precisely controlled shape. You *could* put a complicated and heavy support structure around a space mirror to adaptively shape and focus it, but you sure as heck won't see this on any solar sailcraft.
Sailcraft don't need to focus light; they just need to reflect or scatter it more-or-less backwards (or at least, less forwards than it was when it came in). Thus, they don't bother with heavy focusing gear, and so wouldn't be able to burn holes in anything if they tried.
Re:Something is odd here (Score:2)
Well, I can't speak for anyone else, but I'm paying attention to this project because it's interesting.
If I ignored everything connected to anyone who might have some weird ideas, I'd have to stop reading Slashdot. Hell, I'd have to stop reading, period.
Re:enough funding? (Score:1)
Re: Not hot enough for ya? (Score:2)
And what is the distance of the focal point? The energy density at the focal point is inversely proportional to the square of the distance is it not? Will the huge sail even have a distinquishable focal point?
stupid command line! (Score:1)
while testing.
Re:Let's do the math (Score:1)
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OOPS (Re:Let's do the math) (Score:1)
You have: 5422809.3watts/yard^2
You want: watts/in^2
* 4184.2664
In other words, your original calculations were pretty good. (my mistake).
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Re:I suspect the Russians (Score:2)
Re:I suspect the Russians (Score:2)
Bill Murray (as Bob) said it best... (Score:1)
In the future... (Score:1)
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Let's do the math (Score:1)
That's absurd. Have you ever played with a fresnel lens? I've used one square foot of focused sunlight to burn holes in non-metals (including my hand :(!
For the unscientific, read the link below to see how a 3' circle of sunlight, concentrated to a square centimeter, can melt Aluminum. For the lovers of conversion factors, read on:
I'm going to trust an astrophysics grad student for a conversion factor on this one (http://www-personal.umich.edu/~bclee/lens.html). He says the sun puts out 1340 Watts/m^2 at the Earth's surface, before atmospheric absorption. Mississippi State says there are 43,560 square feet in one acre. My trusty ti-83 says that 1 acre * 43560 ft^2 / acre * (12 in)^2 / (1 ft)^2 * (2.54 cm)^2 / (1 in)^2 * (1 m)^2 / (100 cm)^2 * 1340 W / m^2 = 5.4 megawatts from one acre of sunlight.
My light bulbs put out 100 Watts over somewhere around 4*pi*(3 in)^2 (yeah yeah that's a great approximation :), making 113 in^2. About 1 Watt / in^2. As opposed to 5.4 megawatts spread over a 3 foot square, as you said, which yields (5400 kilowatts) / (36 in)^2 = 4.2 kilowatts of power per square inch. Ouch!
This is all fraught with inaccuracy, and the atmosphere does soak up quite a bit of radiation, but I sure hope i'm not off by a factor of 4,200. Did I miscalculate something?
Re:Good, solar sails are too dangerous to be allow (Score:3)
The solar foils added to ISS/Alpha recently were half an acre in size. This means that if aligned nicely, you can see ISS/Alpha with your unaided eyes. Oooh, the danger. I'm afraid.
If you can focus all of the solar light that hits an earth-acre space, into a much smaller space (say, a 3' square) on the ground, yes, it's gonna be hot and perhaps dangerously hot. But not weapons-grade dangerously hot.
You've been reading too many scifi novellas.
Re:Thus... (Score:2)
"AAaAGGHHH! Not that button!" - As they're all tangled in foil and squashed against the ceiling. - "Real cool Yuri. Now help me get this folded back up before they come
Jon Sullivan
This is not NASA (Score:3)
An interesting note, this solar sail is to be launched atop a former ICBM from a submarine. That, my friend, is the essence of cool.
What "US-Russian space hegemony"? (Score:1)
That's why I'm patenting my new "SPACE-LASER-FACE-NOT-BURN-OFF STUFF" (TM). If you send me $20 I'll send you a WHOLE ROLL of tin foil so those nasty buggers don't melt your face or your MP3 collection. Hurry! Before it's TOO LATE!!
G.H.
This is NOT a
Re:Good, solar sails are too dangerous to be allow (Score:1)
=\=\=\=\=\=\=\=\=\=\=\=\=\=\=\=\=\=\=\=\=
Re:This is not NASA (Score:3)
I always wondered why we never heard more of this. From my understanding, the basic concept was dragging several mile long tether through the earth's magnetic field, generating electricity. From what I heard, they energy produced was so much greather than what they expected, the tether broke and the circuit breaker tripped (is was supposedly rated at a very high rate too).The experiment was not a failure, they just underestimated the energy that would be produced.
This experiement seemed to have shades of Tesla written all over it (ie The earth is a giant capacitor), but I never heard anything more.
Martians REALLY don't want us there... (Score:1)
Don't know if this is the case (Score:3)
Saves them from the embarassment of launching something that will not work. On the other hand it does end up with a correct item that works as expected so everyone is happy.
Again, just something to think about.
DanH
Cav Pilot's Reference Page [cavalrypilot.com]
enough funding? (Score:1)
Re:This is not NASA (Score:2)
And in the case of tethers, 'This is not NASA' typically means 'This works'.
e.g., the Small Expendable Deployment Systems (SEDS) [tripod.com] which is a dirt-cheap (by aerospace standards) system that has flown successfully several times.
Re:Good, solar sails are too dangerous to be allow (Score:1)
First of all, mirror != magnifying glass.
Second, "scale that up to a beam of light"?!? I am left wondering what the hell did you shine through your first magnifying glass? Or did your parents think the combination of lenses and light were too dangerous?
Third, something in space that is acre in size is relatively tiny to a human observer on earth.
Cripes, man, you should write for Star Trek.
Re:Figures (Score:1)
quality control (Score:1)
Instead of the test, actual spacecraft operations began...
doesn't sound like a really tightly managed operation!!
Can't you see them testing their nuclear missiles? Oops! Actual missile operations began...
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Re:This is not NASA (Score:1)
"Star Trek: First Contact" comes in mind
Blessing in Disguise (Was: Something is odd here) (Score:2)
Perhaps the peak of the solar cycle will have passed by then. IANAA (A=Astronomer), but I gotta wonder what a Coronal Mass Ejection would do to a thin sheet of mylar. Imagine not being able to AIM SolarSail1...
If you love God, burn a church!
Re:I suspect the Russians (Score:1)
Good, solar sails are too dangerous to be allowed (Score:5)
Before you condem me, think of the facts. They are talking about orbiting a huge, acre sized, piece of mylar, with controls to change it's orientation.
It's a giant space mirror!
For those of you didn't read the Mars trilogy, think back to the first time you played with a magnifying glass in your backyard.
Now, scale that up to a beam of light, a yard wide and more intense than a steel melting laser beam. Think what the beam of light could do to any cities or countries that don't kow-tow to the US-Russian space hegemony.
Worried yet?
Colonizing the Universe With Solar Sails? Not. (Score:1)
Notorious Time Travel Crackpots [gte.net]
Thus... (Score:5)
Dancin Santa
Re:Good, solar sails are too dangerous to be allow (Score:1)
But you can't. A perfect mirror can't focus a 1/2 degree wide source into anything smaller than 1/2 degree, as seen from the mirror.
That means the size of the image of the sun will be roughly 1/100 of the distance to the mirror. If the mirror is 300 feet away, it could focus the sun into a 3 foot circle, and you'd have to worry about it getting hot. But the sail is going to be hundreds of miles away, and won't add noticeably to the heat from direct sunlight.
There's no risk at all. The original post was a joke.
Re: Not hot enough for ya? (Score:1)
Construction of such a mirror isn't just hard, it's theoretically impossible. You can't focus the sun's image into a 3' circle unless the mirror is within 300'. You just can't.
The people talking about melting things with Fresnel lenses were using much shorter focal length lenses.
Think about the way camera lenses are rated: f/1 is a nice bright lens, able to concentrate a lot of light on the film.
A 3' Fresnel lens with a 3' focal length is an f/1 lens. I don't know the actual dimensions of the solar sail, but if it's an acre in size, it's around 200' in diameter, and it probably needs to be at least 100 miles from its target, so it's going to be like an f/2500 lens. An f/2500 lens is 6 million times dimmer than that Fresnel lens.
Re: Not hot enough for ya? (Score:2)
The sun isn't a point source. It's about half a degree across, as seen from here.
Its image will be about half a degree across, as seen from the mirror.
If the mirror is 100 km up, that means the image of the sun will be around 1 km across.
It won't be very hot, unless the sail is much bigger than that.
Re:This is not NASA (Score:5)
Actually there were space shuttle experiment in 1992 and 1996 to study the use of tethers. Look here for more. [nasa.gov] I believe at least one of these experiments ended in failure when the tether broke; both tethers and solar sails are highly susceptible to micrometeorite impacts.
NASA has also flown experimental ion propulsion technology on the Deep Space 1 [nasa.gov] mission, and has a research team at JPL investigating advanced propulsion concepts [nasa.gov]. You may have heard of a proposal for magnetic-assisted propulsion to travel to Pluto; IIRC that was one of theirs.
I don't know of any NASA attempt to use solar sails, though.
Re: Not hot enough for ya? (Score:1)
"Leave the strategizing to those of use with planet-sized brains." -Tycho
Designed for Windows (Score:1)
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Something is odd here (Score:1)
Three weeks to two months? Most space missions are in terms of years, I don't think this is a major setback.
The project is sponsored by Cosmos Studios, an entertainment company founded by Ann Druyan, widow of the late astronomer Carl Sagan, and Joe Firmage, a Silicon Valley entrepreneur and part-time UFO investigator.
Now I'm suspicious. Why are we paying attention to a Russian project, funded by an entertainment company, and promoted by some UFO nut who believes in aliens?
Solar sails could be useful I suppose. As one insightful poster mentioned awhile back (qpt), it's good to explore a non-polluting source of energy. We don't need to go filling up space with our filthy combustion fuels, and using atomic radiation as a power source. All the clean, reliable power we need can be obtained from our sun!