h a l f b a k e r yCogito, ergo sumthin'
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Have they sent Mir crashing into the atmosphere yet? Well I wish they wouldn't. They should salvage it. Not for reuse, but for valuable space scrap metal. Same with all those dead satelites, booster rockets, and other space debris. Someone should collect it all and form an orbiting space scrap heap.
Or at least send it crashing down on the moon in a designated lunar dump area. There may be a time in the near future when we'll wish we had several thousand tons of scrap metal up in space.
Advanced Propulsion Concepts
http://sec353.jpl.nasa.gov/apc/
A veritable Halfbakery of wacky propulsion concepts. [egnor, Dec 15 2000]
The above idea would make for some interesting junkyards
Near_20Earth_20Orbi...ation_20Corporation
Here's some folks who can help you collect the goods [normzone, Jul 11 2011]
[link]
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There's a difference between "space" and low earth orbit, where most "space trash" is. To boost trash free of Earth's gravitational influence, or even to the moon, is an expensive proposition. Most space junk consists of small bits like paint flakes and bolts, so it's not even practical. I agree it's a waste of potential energy, though. |
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Solar mirrors powering big electromagnets could collect at least some of the junk...and rather than just let it burn up, salvaging it for later use is a good idea. Wouldn't need to land it anywhere, just get it into a stable orbit. At least some of the dead satellites would have even a little fuel left, and it could be used to help... |
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And being able to reduce the possibility of damage to spacecraft would be a big help as well. The Shuttle windows have to be replaced fairly frequently becuase those paint flakes beat the hell out of them... |
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One of the problems with doing stuff in space is that accelerating requires both energy and mass. Things like solar cells can provide power essentially forever, but can't be used forever for providing accelleration power since the only way for a space craft to accellerate is to throw out mass. |
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I wonder if space junk could be useful as something to push against? |
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You can get away with throwing less mass for acceleration if you throw it faster. How big would your solar array need to be to power a cyclotron? (Yeah I know, ion drives are Baked. I'm just armchair engineering here.) How much matter could a decent-sized cyclotron throw out, and how fast would the particles be moving--say, with a c-tron 2 meters in diameter? |
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egnor: What I'm thinking is the precursor of the synchrotron--the particle spirals in the magnetic field until it reaches the outside of the cyclotron and exits. I don't any books with me, but as I recall this is simpler than a synchrotron and even possible without supercooling(?--not sure). |
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Am I keeping cyclotron/synchrotron straight here? |
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I'll see if (later) I can come up with some sort of ballpark figures for what might be a reasonable ejection speed for particles and the resulting kinetic energy given a fairly simple accelerator. |
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[Oh, wait: cheap dictionary. 1 to 10 MeV.] |
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A lot of the space junk is paint chips and other useless stuff. Powder that and charge it and use it to feed the electric jet. |
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Any way you can collect the potential energy of all that stuff up there? One ton of stuff comes down and a ton of working brand new satellite gets up. |
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The cost of space shuttle launches, averaged over the life of the program, works out to about US$15,000 per kg of payload, which is about half the price of gold. That stuff is valuable up there! (+) |
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It may be possible to add to orbital velocity without propulsive mass. There has been some suggestion that a tethered satellite could use the tether as a rotor with the earth('s magnetic field) acting as the stator. The introduction of an electric field of the proper polarity to the tether would result in a mild acceleration (and very small slowing of the earth to balance). To the best of my knowledge there hasn't been a practical test of this approach (although the reverse, generating current at the expense of orbital velocity, I believe has). |
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I'm thinking that the electronic components and various mechanical bits are worth a lot more than scrap metal. If you want to use solar power and salvaged mass for propulsion, the metallic bits are best fed into the accelerator, and used to move the complex parts to a safe location. |
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The real problem is that it costs an unbelievable amount of
money to send stuff into orbit, much less to get it back
down in any kind of usable form. Yes, some of the junk in
orbit contains gold and other high-value materials, but it
would cost much more to even put together a space-
salvage program, much less operate it, than we would ever
recoup from the material recovered. |
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[Alter] Pretty sure the idea is for orbital re-use. Put together all the scrap along with a solar smelter and you're a long way towards a viable orbital industrial plant. If it saves lofting more material than the the mass of the plant, it's beneficial in the long run. |
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Aha... Now that I can get behind. Very cool. |
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(totally missed that the first time around, thanks) |
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That's why I said "That stuff is valuable up there!" rather than "That stuff up there is valuable!". |
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Make it a requirement that each satellite put into orbit should be able, at the end of its useful life, to be sent to a designated junk yard point on a stable orbit. As the amount of stuff in one place builds up, it will become a, local, mini-moon. As this moon builds up is gravity it will start to collect the smaller bits of junk to it or at least knock them out of there stable orbits. |
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Re the particle accelerator, how about throwing electrons. One electron accelerated to exactly the speed of light has how much mass? |
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//One electron accelerated to exactly the speed of light has how much mass?// |
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Particles with mass, such as electrons, can only asymptotically approach the speed of light - they can never reach it exactly, which would in theory take infinite energy. |
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