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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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Of course, you'll need real hardware to go with that.
Ok, jokes apart now hehe.
Someone writes on slashdot days ago about the interesting idea of put a "shield" on space made with a plastic soft container, for example a large plastic bag. fills then with water, the water frozens and you get a good ice shield to put on path of debris. once the shield caugth the debris then can send back to Earth on a planned reentry or ejected to deep space
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But aren't all of those 'solutions' already considered?
Space garbage zapping: You'll end up with particles and debris that is smaller and more difficult to track. Given a speck of paint in space has the same effect as a bullet on earth I don't know if we really want that.
Space garbage collecting: However you try to do it, your spacecraft would have to either maneuver very very well in order not to be destroyed itself (making even more debris) or have such heavy shields that would make it nigh impossible to get into space.
Space pushing into the atmosphere: Just like garbage collecting, your spacecraft will have to be careful. On the other hand it would also be possible that with a slight miscalculation you push it into an orbit that's either much more dangerous (if it bounces instead of incinerates) or more difficult to track and clean up. Next to that some things might just give other side effects here on earth. What do you think would happen if you push an old satellite with some type of nuclear fuel into the atmosphere and it doesn't burn up completely the way you want it to and it basically becomes a dirty bomb in high orbit.
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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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Wow. Just, wow.
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To be clear, they are not talking about blowin' up space junk with lasers. The laser will instead slow down small pieces of space debris so that their orbits deteriorate. (Blowing things up is the domain of the other Project Orion.)
This mechanism is called a laser broom, and there is a short entry about it on Wikipedia. I can't seem to find a more detailed, technical description of how this process works.
Eventually we will have that solar shield that the repair-global-warming crowd keeps raving about.
One cubic foot of water is around 60 lbs.
I thought that number sounded a bit high as a gallon only weighs about 7 pounds, but sure enough, a cubic foot of water DOES weigh around 60 lbs. 62.42796 pounds to be exact. And a gallon is actually just over 8 pounds.
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Orbital mechanics work in strange ways. For example, in a circular orbit, you don't thrust up to go up, you thrust forward. Going down, you thrust backward.
In this case, your best bet will be to hit the forward side of the object. If that's not possible, then hitting the bottom of it (depending on where it is in the orbit) will also have an effect. I can't remember offhand what happens from in-plane radial delta-V application, but I think it's a combination of changing the eccentricity of the orbit without affecting the total energy, and changing the longitude of periapsis. Sorry, it's been a couple years since I took orbital mechanics...
Now if you get a space-based laser up, you get more freedom in how your burns are applied.
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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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Oh wow . . . imaging having that game on-line. 1. Create a mobile base with a laser in space 2. Sell tickets on-line to shoot space debris for 5min 3. ?? 4. Profit!
Which puts us one step closer to landsharks.
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"You're right," Fisheye says. "I should have set it on 'whip' or 'chop.'"
It was very costly to put all that mass up there - it should be collected and eventually recycled in orbit. Basic physics.
Given the price of launching things to space, you could use scotch whiskey instead and it wouldn't affect the cost or feasibility of this plan.
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Unfortunately, most of the folks on here are probably too young to get the reference, so, here's some text from the original boxes:
Build it, and they will come^Hplain.
The proposed Orion space debris laser fits nicely with our recent problems of creating so much debris in LEO. It would be a single pulsed laser on an equatorial mountaintop capable of ridding LEO of hazards in 4 years.
With the recent collisions this is becoming imperative. We need to have a clean LEO environment or we aren't going to do much in space.
http://www.spacefuture.com/archive/orions_laser_hunting_space_debris.shtml
http://adsabs.harvard.edu/abs/1997SPIE.3092..728P
http://en.wikipedia.org/wiki/Laser_broom
http://cat.inist.fr/?aModele=afficheN&cpsidt=3109525
Water makes a great shield inside a space station but is a dumb idea for "collecting" debris.
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Something doesn't seem to add up. They've already indicated that slight modifications to trajectories can deteriorate an orbit, so some portion of the space junk caused by collisions must fail to remain in orbit. But they also say that collisions cause more junk, which causes more collisions, as though this were a never-ending cycle of feedback.
It seems as though there must be a threshold somewhere where the introduction of further space junk removes from orbit, on average, an equal amount of debris as it introduces. The farther past this threshold, the more likely that introducing debris will remove more than is introduced. There must be a point of equilibrium.
Take the following exaggerated scenario, for example. Let's say that by chance or plan, there is debris in orbit within every cubic meter at stable altitudes. (I am not a physicist, but this seems highly improbable statistically.) The introduction of a meteoroid through this debris field would almost certainly cause a significant chain-reaction with many affected objects acquiring unstable orbits leading to failure.
Not-to-scale pictures aside, I doubt we're anywhere near such a threshold -- even if we are reaching a point where our ability to avoid debris is insufficient to mitigate the danger. But surely it would be at least interesting, if not practically useful, to know this "saturation" point.
Or perhaps this is already known, and I am just unaware.
There are at least two different "inches", the survey inch and the standard, or international inch.
The main problem with imperial units (apart from the aforementioned different standards in different parts of the world) is that there are so many units for a single measurement. Length can be measured in inches, in feet, in yards, in furlongs, in fathoms, in rods, in chains, in miles, and who knows how many others. Volume is even worse. Not only do you have teaspoons, tablespoons, ounces, cups, pints, quarts, gallons, etc. but there is the whole pantheon of cubic length units: cubic inches, cubic feet, etc. A pound of gold weighs less than a pound of feathers because precious metals and gems are weighed in troy units and common items like feathers are measured in avoirdupois units.
To further add to the confusion, each unit is a different fraction of the others. 12inches to the foot. 3 feet to the yard. 16 ounces to the pound. 2000 pounds to the ton. And to top of all that confusion lies the convention that you need to need to use at least two units for each measurement: Joe is 5ft9in tall. He weighs 177lbs, 14 oz.
Heaven help you if you want to calculate anything.
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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.
Actually, it is likely that a lot of the water will come back to earth. In a LARGE number of years.
Most of it will come back immediately. The water spray itself, aimed to transfer momentum to the debris in order to deorbit it, should itself be in an atmosphere-intersecting trajectory. The bulk will miss and end up in the atmosphere.
What gets blasted into steam will still be deep in the gravity well. Most of it will be perturbed into denser atmosphere in reasonably short order. (Remember: The atmosphere doesn't "end". It peters out gradually until it merges with the solar wind out at the magnetosphere shock front.) Some will be ionized and the hydrogen will tend to blow away, leaving hydroxyl radicals and monatomic oxyygen - much like what naturally happens in the upper atmosphere already.
You WILL see an increase in upper atmosphere water and noctilucent clouds. But we're probably not talking enough water to have any other significant environmental impact. (Better use deionized water, though. Any chlorine would be a real issue for the ozone. I'm normally a debunker of ozone-hole hand-wringing but this could be significant.)
As to "running out of water": Think of the size of the oceans. We're talking a VERY small drop from a VERY big bucket.
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Send up seawater.
Distill, reverse-osmosis, or otherwise purify it first.
I'm normally one to debunk hand-wringing about the ozone layer. But most of the sprayed water will miss the debris and impact the upper atmosphere immediately (while the rest comes down slowly over many years). If you use unpurified sea water you'll put a LOT of chlorine ions from sea salt into the ozone layer - near the equator where it's a big deal - and chlorine is the catalyst for the ozone->oxygen transition that got freon banned.
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