47 replies to this topic

[jon3831]

Christopher, on Feb 22 2003, 05:45 AM, said:

Another possibility would be a wide swath of aerogel, a very diffuse but sturdy foamlike material (that "very fine netting" you mention, only much better).

I thought of Aerogel last night whilst looking for the news to catch up to our earthquake last night... It would have the advantage of being able to absorb multiple impacts at the velocities we're talking about...

http://eande.lbl.gov...ogels/satoc.htm

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Aegis: Of course you have the question would be how many shots you could manage with the fuel available and all the International hang-ups of a high powered laser in space.

Yeah, you're right... You'd probably have to get an amendment to the Outer Space treaty...

http://www.oosa.unvi...aw/outerspt.htm

[Nick]

I don't see how a laser would really help much . . . I mean--whether its a chunk of metal or a bunch of little bits of metal hitting a spacecraft . . . it could still do significant damage . . . just spreads out the debris I think . . . Unless you get complete vaporization, which I don't see as feasible from a space-based laser w/ present tech.

*shrugs*

BTW it looks like there may have been 3 foam strikes during takeoff:
http://www.cnn.com/2...tion/index.html

-Nick

[Edit: messed up tag]

Edited by Nick, 23 February 2003 - 12:32 AM.

[CJ AEGIS]

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jon3831:
I thought of Aerogel last night whilst looking for the news to catch up to our earthquake last night... It would have the advantage of being able to absorb multiple impacts at the velocities we're talking about...

Though it still seems like you would be dealing with a fuel intensive operation with all the tracks you would have to sweep. Even then are these aerogels that resilient to be able to absorb an impact at those velocities?  

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jon3831: Yeah, you're right... You'd probably have to get an amendment to the Outer Space treaty...

Does that treaty just cover nuclear or WMDs?  A spacer based ABL really wouldn’t have the power to penetrate very far through the atmosphere so I really wouldn’t count it as a WMD.  

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Nick: Unless you get complete vaporization, which I don't see as feasible from a space-based laser w/ present tech.

As I understand it most of the space debris that endangers spacecraft is actually fairly small.  Stuff like paint chips and other small debris.  The ABL is at least a megawatt range laser so it should be sufficient to take out small debris like that.  It might work for a combination of nets to catch large debris you can’t vaporize and lasers for smaller debris.

[Banapis]

One of the more exotic solutions I've read to the space debris problem:

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Li says that if the ions in an HTSD are aligned by a magnetic field, the gravito-electric fields they create should also align. Build a large enough disc and the cumulative field should be measurable. Build a larger disc and the force field above it should be controllable. "It's a gravity-like force you can point in any direction," says Campbell. "It could be used in space to protect the international space station against impacts by small meteoroids and orbital debris."

http://popularmechan...ity/print.phtml

As a side note, Gravity Probe B (mentioned in the article as having been designed to measure the gravito-magnetic energy produced by the Earth) has suffered a few setbacks since that article was written and is now scheduled for a July 20 launch on a Delta 7920 at Vandenberg Air Force Base.

http://www-pao.ksc.n...le/mixfleet.htm

Banapis

P.S. It's also kinda interesting to ponder if such a gravity-like force could ever be applied as form of propulsion.

Edited by Banapis, 23 February 2003 - 04:40 AM.

[Nick]

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In an HTSD, the tiny gravitational effect of each individual atom is multiplied by the billions of atoms in the disc. Using about one kilowatt of electricity, Li says, her device could potentially produce a force field that would effectively neutralize gravity above a 1-ft.-dia. region extending from the surface of the planet to outer space.

That sounds a bit odd.  If that's really what this device is (theoretically) capable of . . . could it work on an even larger scale?  say a launchpad sized device that would create a column of neutralized gravity greatly reducing the fuel requirement to get to orbit?

And now that I think of it . . . if the gravity were "switched off" in a columnar region all the way up to space . . . wouldn't it cause some major atmospheric problems? i.e. w/o gravity holding our pressurized atmosphere in . . . seems like it would cause something of a gas jet spurting out into space . . .

-Nick

Edited by Nick, 23 February 2003 - 05:34 AM.

[Christopher]

CJ AEGIS, on Feb 22 2003, 08:10 PM, said:

Though it still seems like you would be dealing with a fuel intensive operation with all the tracks you would have to sweep. Even then are these aerogels that resilient to be able to absorb an impact at those velocities?

Well, how fuel-intensive is it to operate a fleet of garbage trucks?  If it needs to be done, it needs to be done.

And I'd say aerogel is definitely resilient enough.  Since it's so low in density, it's a very good insulator, so the heat and kinetic energy generated when a particle impacts and vaporizes will not be transmitted very far.  It's an ideal ablative material.

[Delvo]

Nick, on Feb 22 2003, 08:34 PM, said:

could it work on an even larger scale?  say a launchpad sized device that would create a column of neutralized gravity greatly reducing the fuel requirement to get to orbit?

And now that I think of it . . . if the gravity were "switched off" in a columnar region all the way up to space . . . wouldn't it cause... a gas jet spurting out into space

I'd bet that, although the physics behind it would still apply if such a thing were built at large scales, the cost of actually doing so would be prohibitive. That's a mighty big chunk of superconducting Bose-Einstein condensate latticed ions there... or a mighty big set of little ones to work together.

But if it can be done at all, the problem you describe sounds solvable by fitting the vehicle with one on the bottom and another on top to counter it... or just one, on the top, instead of the bottom. Think about it... for the one at the bottom to "point" up above it, it has to be set to repel, and, for the one on top to point down above it (so air's not pushed up), it has to be set to attract. Now picture the ship between them. There's a force under it repelling, and a force above it attracting; BOTH forces are pointing up as far as the ship is concerned, and that force remains constant (so the ship constantly accelerates) because the force generators are attached and go along with it. This wouldn't just reduce the rocket thrust needed, it would negate the need entirely; no more producing fuel and rocket engines. A similar effect could be expected from a single generator on the top of the vehicle, set to attract, without one at the bottom at all.

[Nick]

Delvo, on Feb 22 2003, 10:51 PM, said:

I'd bet that, although the physics behind it would still apply if such a thing were built at large scales, the cost of actually doing so would be prohibitive. That's a mighty big chunk of superconducting Bose-Einstein condensate latticed ions there...

I'm having a hard time seeing what could be "prohibitive" if it virtually eliminates the need to takeoff with a great deal of fuel . . . If the device costs billions or even trillions, it would be money well spent, IMHO.  And promptly pay for itself with the tremendous savings on launch expenses . . .

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But if it can be done at all, the problem you describe sounds solvable by fitting the vehicle with one on the bottom and another on top to counter it... or just one, on the top, instead of the bottom. Think about it... for the one at the bottom to "point" up above it, it has to be set to repel, and, for the one on top to point down above it (so air's not pushed up), it has to be set to attract.

Assuming it can be set to actually apply a force beyond simply negating gravity, then we have--essentially--a reactionless drive (okay, not really . . . nature always balances her books, so whatever bodies it alters the gravitational attraction to/from are moved with just as much force as our imaginary spacecraft) . . . which becomes *terribly* handy.  But even if the condensate can't *generate* additional forces beyond negation of gravity . . . getting in to orbit would become a cakewalk . . .

But you have a good point with mounting one on top of a spacecraft, it just hadn't occured to me to "think upside-down".


-Nick

Edited by Nick, 23 February 2003 - 07:17 PM.