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Using Lasers and Water Guns To Clean Space Debris
WSJdpatton writes "The collision between two satellites last month has renewed interest in some ideas for cleaning up the cloud of debris circling the earth. Some of the plans being considered: Using aging rockets loaded with water to dislodge the debris from orbit so it will burn up in the atmosphere; junk-zapping lasers; and garbage-collecting rockets."
Wouldn't it be extremely expensive to send large quantities of water into orbit (also, our water supply is limited we can't be throwing it into space!)?
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> Sharks can fly to space?
That's what the water is for.
Not only would lofting water into space be a colossal waste of energy and water, it would only exacerbate the problem!
IMHO the only 'clean' way to deorbit debris is to add energy to the debris in the retrograde direction without using additional mass, which means photons. Laser pulses could do it either by radiation pressure directly (huge laser), or by pulses that ablate the debris slightly (creates tiny beads of additional debris).
Electron/proton beams would work as well, as would alpha particles, but they'd pose a risk to humans in space. In fact, using charged particles might induce a charge on the debris that would then help direct the debris toward it's doom (debris vector, Earth's magnetic field, right hand rule....whatever).
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Since space is a "near" vacuum wouldn't the water flash to steam instantly and be useless?
The enthalpy of vaporization for water is very large. On exposure to vacuum, immediately the water will begin to boil. This will very rapidly cool the water so that most of it ends up freezing (the enthalpy of fusion is comparatively much lower). Not only does this make mathematical sense, but it's witnessed daily on vacuum lines in labs.
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Which puts us one step closer to landsharks.
*knockknock* "Plumber!"
"You're right," Fisheye says. "I should have set it on 'whip' or 'chop.'"
We spent hundreds of hours in front of the Astroids simulator, practicing breaking rocks up into smaller rocks!
I've abandoned my search for truth; now I'm just looking for some useful delusions.
Your imagined point of equilibrium is the point where there's nothing but space garbage, and if you shoot up more there'll be more garbage even though some of it falls back. I'm sure you remember Newton's law of conservation of momentum, now apply it to two oribiting satellites on almost similar trajectories crashing into each other, breaking into many pieces. Basicly, they'd become a spray of junk, some going up, some down, some faster, some slower. They'll spread out as if you fired a shotgun, catching up to some satellites while slowing down covering a greater and greater area to collide with others which will again behave the same way. It doesn't matter if 90 of 100 bits fall to earth if they take out >1,1 satellite each on average. It'll just escalate exponentially like a nuke going off, leaving a fine layer of bullets all over the stable orbit.
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This is a good point. But as collisions become more and more frequent, I don't think they be able to maintain momentum. The energy from each collision is spread out among all the fragments produced, and also some is lost during the impact as heat and the energy required to separate the fragments from the larger original pieces.
Let's say that "first-generation" objects are on a stable orbit with sufficient momentum to maintain orbit. After impact, some of the resultant second-generation fragments will fail orbit quickly due to grossly incorrect trajectories, while others enter trajectories that will take longer to fail. Over the time it takes for these second-generation fragments to fail, they cause more impacts. More of these third-generation fragments are lost more quickly, and the remaining ones proceed to cause fourth-generation impacts, and so on. This is the general chain-reaction idea being posited.
One factor to consider is the fact that as these particles reach higher "generations", they are in more and more grossly failing trajectories due to either bad vectors or insufficient momentum. These trajectories intersect less and less with stable orbits, so the collisions are more and more likely to be with already-failing particles. This could only accelerate the orbit failure. Essentially, these particles should clean themselves up.
Again, I am no astrophysicist, but it seems that if chance supported easily-achieved orbits, then we would already be at saturation. The fact that we're not suggests that the "random collisions creating a permanent* cloud of debris" theory may not be self-supporting.
Of course, it may be that the time it takes for this debris field to fail is on a scale which is inconvenient to us. But to say that we'll eventually end up with a stable cloud of microscopic bits just doesn't add up.
Saturns rings would like a word with you. ;)
j'ai découvert une démonstration vraiment admirable (de ce théorème général) que cette si