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US Claims Satellite Shoot-Down Success
Posted by
CmdrTaco
on Thu Feb 21, 2008 08:44 AM
from the hope-your-foil-hat-was-on-snug dept.
from the hope-your-foil-hat-was-on-snug dept.
Readers of Slashdot last valentines day will remember discussing US Plans to Shoot down a damaged spy satellite. An anonymous reader noted that the US is
reporting success last night, thus saving us from hydrazine exposure. Of course this makes me wonder- if it's this easy, wouldn't an international super power war pretty much immediately mean the downing of every satellite in orbit?
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US To Shoot Down Dying Satellite 429 comments
A user writes "US officials say that the Pentagon is planning to shoot down a broken spy satellite expected to hit the Earth in early March. We discussed the device's decaying orbit late last month. The Associated Press has learned that the option preferred by the Bush administration will be to fire a missile from a U.S. Navy cruiser, and shoot down the satellite before it enters Earth's atmosphere. 'A key concern ... was the debris created by Chinese satellite's destruction -- and that will also be a focus now, as the U.S. determines exactly when and under what circumstances to shoot down its errant satellite. The military will have to choose a time and a location that will avoid to the greatest degree any damage to other satellites in the sky. Also, there is the possibility that large pieces could remain, and either stay in orbit where they can collide with other satellites or possibly fall to Earth.'"
Submission: US claims sattelite shoot-down succes by Anonymous Coward
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in other news (Score:5, Interesting)
Re:in other news (Score:5, Insightful)
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Re:in other news (Score:5, Funny)
I'm waiting for the anti-(anti-missile missile) missile
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Re:in other news (Score:5, Funny)
The US Navy announced that due to bad weather, it will postpone the attempt to shoot down the impaired satellite until tomorrow at the earliest. Our zillion dollar "star wars" technology is clearly capable of stopping incoming missiles so long as: they come one at a time, are the size of a school bus, travel in orbits that have been calculated for months, don't deploy any decoys, and the weather is clear.
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Re:in other news (Score:5, Informative)
Russia goes on about us using it as a cover for anti-satellite testing. As sh00z [slashdot.org] mentioned, it's an anti-missile missile. Then they ramble about how toxic fuel has crashed to Earth before and how they think it isn't a big deal. But since we didn't know where it would exactly land and don't have the luxury or using Siberia or Kazakhstan as a crash site, there could be enough risk of exposure to civilians as it was projected to hit North America. Besides, I'd like to hope we shoot for a higher safety standard than Russia. They do a lot of really cool things for really cheap
I found China's response is both hilarious and hypocritical. Their concern about security in space is a joke given that they hit a real satellite just last year. At 800 km against our 200 km! I think their test says more than ours in the international dick waving sense - plus a majority of their debris won't burn up within a week. I don't really see the two launches as apples to apples; more like China totaling a working 1993 Honda and the US totaling a 2007 BMW with a cracked engine block.
Odds are quite good that it was really just to destroy the top secret components on the satellite. Fair enough since it's our tech and we don't like giving it away. The environmental concern with the hydrazine happens to be convenient whether as a cover or for real legitimate concern - hydrazine is nasty stuff regardless. As for a weapons test, the missile couldn't hit a satellite in use. It really could only be useful as both a cruise phase interceptor test and a cold tracking (no infrared) sensor test. Besides, it's been known for years that the US can hit working satellites - no need to flip out over hitting a lame bird.
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They need to be more careful. (Score:5, Funny)
priorities? (Score:5, Informative)
Re:priorities? (Score:5, Funny)
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Video (Score:5, Informative)
Yes they expect them to fall out of the sky... (Score:5, Informative)
It's not about hydrazine- and it's not new. (Score:5, Informative)
2. The likelihood of the propellant tank making it to Earth in a populated area while still sufficiently intact to release hydrazine on impact is infinitesimal. The satellite was launched in 12/06, and represents the pinnacle (well, a year ago) of US spy satellite technology. There's plenty of good coverage in The Washington Post that supports both of these points.
Make no mistake about it, this is all about preventing the tech from falling into the wrong hands.
Video of the intercept (Score:5, Informative)
http://www.liveleak.com/view?i=71c_1203596547 [liveleak.com]
Like hitting a bullet with a bullet. Neat engineering feat.
Re:Video of the intercept (Score:5, Informative)
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Cold War News (IE, Old Hat) (Score:5, Informative)
USN's Standard SM-3 missiles are their new Black and Decker tools of fleet defense. They pulled a preproduction bird off the table, loaded a ASAT seeker on it and sent it on it's way.
A little bit more on the new theater missile interceptor;
http://www.globalsecurity.org/space/systems/sm3.htm [globalsecurity.org]
So of course... (Score:5, Insightful)
Summary Info (Score:5, Informative)
USS Lake Erie [wikipedia.org]
Missle Used:
SM-3 [wikipedia.org] with kinetic interceptor [wikimedia.org]
Tracking was probably provided by the SBX [wikipedia.org] amongst other sensors.
Previous intercept videos of importance:
Japan Defence SM-3 test [dailymotion.com]
Prior shot from USS Lake Erie [youtube.com]
The propaganda that I find really funny is the DoD stating that it "nailed" [cnn.com] the fuel tank. C'mon, the impact probably released over 100 megajoules of energy. Were they really aiming for the "fuel tank" or just trying to hit the damn thing? With that much energy, who cares?
Big Dick waiving, yes. Technical success, yes. Political success, TBD.
On a side note, I was reading a story [bwcinet.com] written by a guy who was stationed at Thule AFB in Greenland where one of the first BMEWS (Ballistic Missle Early Warning System) Radars was deployed back in the late 50's early 60's. From a tech standpoint, it is quite fascinating what we could do back then with such limited technology and how it was accomplished. Read the intro through the epilog, I enjoyed it, so I'm passing it along...
Pinata (Score:5, Funny)
This wasn't a sat-kill test (Score:5, Interesting)
The Chinese took out one of their telecomm birds last year. It was 500 miles up and in steady orbit. That was a sat-kill test.
The US spy satellite was a) 150 miles up, b) in unstable orbit and c) a spy sat.
Destroying the super-secret spy technology on the satellite was a bonus.
The shoot down was a test of whether US anti-ICBM systems worked as intended. THIS was the whole point. We've done contrived tests of the missile defense technology before, but here was an opportunity to shoot down a real, faster moving, unpredictably moving target.
Shooting down satellites in stable orbit isn't hard. The challenge is getting a missile up there, and the US has this technology locked. Shooting down a very fast moving object that is coming at you in a more or less unpredictable way is tough. The success of this test makes China and Russia nervous not about their satellites but about their ability to lob missiles.
As for all-our space-war, the challenge would be to be selective. The EMP from a small number of well placed nukes would fry the electronics of nearly every communication and weather satellite in space, not to mention taking the GPS system out of commission. Only a low-tech rogue nation with nuclear weapons, like N. Korea or Iran would in any way benefit from such tactics.
Re:Wasn't that the whole point (Score:5, Insightful)
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Re:Wasn't that the whole point (Score:5, Informative)
The satellite that was shot down yesterday was very, very close to the Earth's atmosphere. It was only one rotation, maybe less, away from starting to graze it (which means that it would slow down and begin to reenter and burn up). If we assume that when it was destroyed, pieces flew in all directions, some of them would have ended up with a greater net orbital velocity at the end. These pieces aren't the ones that exploded *up* (normal to the surface of the Earth), though, they're the ones that exploded *forward* (in the direction of the satellite's motion). They picked up some velocity and would end up in a slightly higher orbit as a result. I suspect it's not much of a higher orbit, though -- if anything, it probably just means they'll take a little longer to hit the atmosphere than other parts. It's tough to say without doing any calculations, but I doubt you have enough Delta-V to push the pieces into a long-term stable orbit. (Unless maybe the rocket fuel detonated.) The difference in velocities between high, long-term stable orbits and low atmosphere-grazing orbits is pretty substantial.
The pieces that flew off in other directions aren't really a huge concern, because they all end up in the same or lower orbits. Plus because you've blasted the satellite into little pieces and thus increased its surface area tremendously, it'll start slowing down on hitting the atmosphere much more quickly, and the pieces will burn up more completely on their way down.
My understanding is that what the Chinese did was quite different. The satellite they shot at was way out in a stable orbit, and thus the pieces it was reduced to stayed there as well. So now instead of a dead satellite floating around in orbit that's relatively easy to track and avoid, you have a vast cloud of small debris. Not an improvement at all.
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Followup and oblig. car analogy (Score:5, Informative)
The way most anti-satellite and anti-ballistic-missile weapons work isn't by blowing up the target, it's basically by just positioning itself in front of the target, and letting physics do the rest. The satellite has a huge velocity in one direction, the missile a huge velocity in the other, they slam into each other -- wham -- target destroyed.
Imagining the satellite just blowing up, with pieces flying everywhere, isn't a good model for the interaction. Although it's not impossible for some pieces to end up with a greater forward velocity than the satellite originally had, conservation of momentum tells us that most of the combined mass is going to end up with a velocity substantially less than what the satellite had to begin with.
(Car analogy: A racecar is going around a track at some incredible speed, say 200MPH. You decide to kill it by taking another car, and driving it in the opposite direction, intercepting the racecar head-on. Without getting too deeply into the mechanics of the collision, the result when the two cars smash into each other is that most of the pieces are probably going to be going less than 200 MPH in the racecar's original direction. Assuming the car's fuel tank doesn't detonate and add a lot of energy to the system.)
So overall, I don't think there's much of a risk with a kinetic ASW that you're going to blast pieces into a substantially higher orbit than where the satellite was originally. If the satellite is already in a high stable orbit, you may have a big cloud of junk in space for a long time though.
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HD Modeling of the Chinese ASAT test ... (Score:5, Informative)
Good model of the debris field caused by the China ASAT test. As you mention, "stuff" doesn't just fly everywhere.
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Re: Wasn't that the whole point (Score:5, Informative)
Orbits have a point of closest approach, which for the Earth is called perigee, and a point of farthest approach which as called apogee. Whenever an approximately circular orbit has a new velocity imparted, the orbit will become an ellipse. The counterintuitive thing about orbital mechanics is that the point where the velocity change occurred (in this case, where the missile hit) will not change on subsequent orbits.
Now assume a particle had an increased velocity because of the missile hit. It now has a "higher" orbit in that the point opposite the missile hit will be farther from the earth. However, its perigee is still the point where the missile hit. Atmospheric drag is significant at the satellite's current altitude, and thus it's velocity at that point will be reduced on every orbit, which will cause apogee to get lower and lower until the orbit is circular and it returns to the entire orbit decaying due to drag. This circularization time is small. Therefore, there is no concern about new orbital debris due to this satellite.
Anything that now has a reduced orbital velocity will only decay sooner, as its apogee is where the missile hit, and the perigee will be deeper in the atmosphere.
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Re:Wasn't that the whole point (Score:5, Informative)
The satellite that was shot down yesterday was very, very close to the Earth's atmosphere. It was only one rotation, maybe less, away from starting to graze it
The satellite was never really out of the atmosphere, because as you go up in altitude, the atmosphere never really stops. The number of molecules per unit volume just gets smaller and smaller.
Every time a satellite hits a molecule, it loses a tiny amount of energy, and that lowers its orbit by a tiny amount. The lower the orbit gets, the more molecules get in the way, so the process gradually accelerates until the satellite "burns in".
At the high altitudes used by communications birds, the concentration of molecules is barely above that of deep space, which I believe is on the order of one per cubic meter, and it can take centuries for the decay process to get on a roll. At the other end of the scale, there is a tipping point around 150 miles up, where the satellite will be losing measurable altitude from one rev to the next, and reentry is imminent; that's where this satellite was yesterday.
In other words, the satellite was on the way down because it was getting lower in the atmosphere, not "close to it".
rj
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Re:Wasn't that the whole point (Score:5, Informative)
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Re:Wasn't that the whole point (Score:5, Informative)
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Re:Wasn't that the whole point (Score:5, Insightful)
What irked me the most was China's whiny statements about the test, which was extremely benign in every regard, while China themselves produced a huge band of debris in a very useful polar orbit for no legitimate reason whatsoever.
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Re:Wasn't that the whole point (Score:5, Insightful)
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Re:Wasn't that the whole point (Score:5, Informative)
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Re:Wasn't that the whole point (Score:5, Insightful)
"In theory, practice and theory are the same; in practice, they are not."
Anyone who has actually had to do installs knows that ABSOLUTELY NO AMOUNT OF LAB TESTING WILL PREPARE YOU COMPLETELY FOR THE REAL WORLD. See: Murphy's Law. See Also: Any angry IT guy: "Dammit, it's ALWAYS something!"
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Re:Wasn't that the whole point (Score:5, Insightful)
Simulations are doomed to succeed.
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Re:Wasn't that the whole point (Score:5, Interesting)
prior to this the maximum ceiling of the missile used was unknown.
We still don't, we're talking about shooting satellites so ceiling doesn't really apply. It is known that the velocity of the missile will taper off as it gains altitude due to gravity and because it's a kinetic kill vehicle that means it's effectiveness is a function of the closing velocity between the warhead and the target. Each potential target is going to present it's unique set of variables through a blend of engineered friability to break it up into small pieces on re-entry to protect the secrets onboard or the public on the ground and the hardening to make it less vulnerable to the space environment and attack; So each satellite shot is unique.
This bird they used, The RIM-161 Standard Missile 3 (SM-3) [wikipedia.org] seems from the description to be rather modular, I bet they can mix and match rocket motors in the various stages to get the parameters they want without to much difficulty. I'd be surprised if we couldn't reach-out and pick off a geo-sync satellite if we wanted to.
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Re:Wasn't that the whole point (Score:5, Interesting)
Now I personally did not know that we had a ship based missile capable of knocking down satellites but apparently we do. However, that is likely not an epiphany for any other country that is capable of fielding an ASAT weapon system. It's highly likely that several other countries were even informed of the planned launch to forestall any tensions that it might have created.
If we did give away any important information as a result of this launch, it's that our president is capable of making rationale decisions every once in a while. It's entirely possible that countries such as China and India were not aware of that.
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Re:Wasn't that the whole point (Score:5, Insightful)
http://en.wikipedia.org/wiki/SM-3 [wikipedia.org]
The problem with hitting a satellite is velocity. Specifically closing velocity. With the kinetic warhead traveling at the speeds that it is capable of and the satellite orbiting around 17,000 mph, closing velocity was up around 22,000 mph. Altitude can always be achieved just by changing the booster series and fuels. Having a guided warhead being able to adapt to and intercept a target moving that fast is the real problem.
I think the capability was soundly demonstrated and while some may think it was a mistake, the BMD system has roots in a previous system that dates back to 1995-96. This capability has been in the hands of the Navy for a while now just no reason to use it or give away what cards were being held in our hand. It was also being developed at that time when we signed the Anti-Ballistic Missile Treaty which not only said we wouldn't develop any new ballistic missiles but we also wouldn't develop a defensive system against ballistic missiles. As far as I know, that treaty is still in place and this is a direct violation of that treaty. Just goes to show how much the Navy cares about foreign policy. Especially since it can park "90,000 tons of diplomacy" off of any shore and have it accompanied by a battle group with enough firepower to put any country that opposes the U.S. back into the stone age.
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Re:Wasn't that the whole point (Score:5, Interesting)
I contend that this was a 3-for: the US got to test it's anti-ballistic missile system, got to protect its secrets, AND got to reduce the risk to people. And for what? No risk whatsoever. If it missed - no change in situation. It hit, though, and so now everything will just burn up.
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Re:Wasn't that the whole point (Score:5, Funny)
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Re:Wasn't that the whole point (Score:5, Informative)
Not necessarily. If the hydrazine tank is parked in the center of the vehicle it's very probable that it could remain cold enough. You completely negate radiation and most likely convection depending on design, so you rely solely on conduction for heating. If you have a big, massive satellite that is densely packed it is conceivable that the center could remain cold, just like the Apollo modules kept three people comfortable for reentry. Also a big dense object like a satellite is likely to stay intact through re-entry with very little breakup.
Although I agree there is much more at stake than just hydrazine, and I think spy secrets alone would have been justification, there's no saying the hydrazine would be completely gone. There's multiple justifications for this shot, they just picked one to tell people.
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Re:Wasn't that the whole point (Score:5, Insightful)
1) Because the risk to human life was non-zero
2) To prevent sensitive technology from going into the wrong hands. (You can bet that there would have been a mad dash to salvage at ground zero by just about everybody once it went down)
3) To further test our ABM technology.
4) To show everybody once again that we kick ass.
5) And most importantly: Because there were no downside to doing it. This wasn't a dangerous mission that put soldiers or civilian lives at risk. We launched a missile, and if it missed, no big deal, no harm done. But if it was a success, we can celebrate because of reasons #1-#4.
There really isn't any valid argument for not trying this operation.
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Re:Wasn't that the whole point (Score:5, Informative)
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Re:Wasn't that the whole point (Score:5, Interesting)
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Re:Wasn't that the whole point (Score:5, Informative)
Absolutely I would claim that.
Hydrazine is a solid below about 1 deg C. This was a dead satellite. No heat, no power supplies. In other words, you have an insulated pressure vessel (fairly well-built) containing 1,000 lb of hydrazine ice at roughly -273 deg C. That's a LOT of thermal mass; the ice inside the tank would absorb a lot of the reentry heat, preventing the metal from melting for quite some time. Did you ever do that science experiment where you try to burn a paper cup containing water? Doesn't work until you boil off all the water. Same thing here, but we're talking about metal which is even more thermally conductive than paper.
Furthermore, a lot of the surrounding structure must ablate or melt away before the tank can be directly affected by the reentry.
Also, in case you want to compare a thousand-pound meteorite to this satellite: a satellite does not orbit as fast as your typical meteor reentry speed, so you cannot compare the reentry energy to a typical meteorite ablation rate.
If you need proof, consider that hydrazine tanks from the Space Shuttle Columbia accident DID impact in some Florida woods. They were NOT cold-soaked at absolute zero for two years - they were prepped for flight, heated, etc., and wrapped in far more spacecraft structure than this satellite. And they were not full, like these tanks were. That should demonstrate the reality of this risk.
Want to see a photo of a far smaller hydrazine tank, and some other unidentified tanks, AFTER they landed in Florida? http://www.io.com/~o_m/clfaq/s3.htm [io.com]
http://www.io.com/~o_m/clfaq/images/debris_shots/tank1.jpg [io.com]
http://www.io.com/~o_m/clfaq/images/debris_shots/tank2.jpg [io.com]
http://www.io.com/~o_m/clfaq/images/debris_shots/tank3.jpg [io.com]
Most interestingly, these bits of spacecraft look completely uncharred, unmelted, almost new except for a lack of paint.
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Re:Wasn't that the whole point (Score:5, Informative)
First, the Columbia hydrazine tank was part of the Columbia...a shuttle. The satellite tank was part of an object that was never designed to survive reentry.
Second, the hydrazine tank on the Columbia was shielded from the worst of the reentry temperatures. The Columbia didn't lose integrity and break up until well into the atmosphere.
Third, the tank was found ruptured.
There's nothing 'similar' about the two scenarios, and the Columbia tank ruptured anyway.
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Re:Wasn't that the whole point (Score:5, Insightful)
Mostly likely they were just worried about sensitive technology that might survive reentry potentially falling into Chinese or other hands. While not a new sat, it wasn't really that old either. I'm guessing decent optics and other gear on there, including comm equipment. Why risk any chance of parts of that surviving and landing in even a damaged state someplace that a foreign power might be able to get a hold of it.
Of course this idea was never even remotely touched on, which I'm guessing is exactly what the military wanted. They are probably more than happy to be getting accused of testing a missile, it means people aren't talking about the thing that really concerned them.
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Re:Wasn't that the whole point (Score:5, Funny)
Oh c'mon everyone...at the very worst, the hydrazine was just an excuse to do something very cool....shooting a missle to blow up a failing satellite. Cool stuff, and no one got hurt.
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Re:Wasn't that the whole point (Score:5, Informative)
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Re:Wasn't that the whole point (Score:5, Insightful)
Physics. The satellite wasn't designed for re-entry (In fact, it's very likely it was designed for breakup during reentry for various security issues) and as such wouldn't have the heat shielding required to protect those parts of the propulsion system from the heat of reentry.
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Re:Wasn't that the whole point (Score:5, Informative)
Maybe you should look at some of the photos of the skylab debris before making your assumptions.
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They needed to remind ME of that (Score:5, Funny)
As a matter of fact, I expect to see some damned fine shooting stars in the next few days, or I'll be asking for my money back.
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Re:"Pull!" [ratchet] [BANG] [ping!]... "Pull!" ... (Score:5, Informative)
If you start blowing up sattelites in stable orbits, you are playing a kind of russian roulette that could start a chain reaction, destroying all satellites in a given orbit zone. The fragments of broken sattelites don't slow down, like on earth, nor is the chance that they come down to earth and burn up in the atmosphere particularly high (especially with high-altitude orbits). They will mostly start zinging around the earth in various orbits until they make contact with another satellite, causing more debris. Here, I use the word satellite in it's loosest sense: meaning a conventional communications satellite, or a space shuttle, or a space station, an astronaut on a spacewalk or even the moon itself.
This kind of event would make the orbits unusable for the foreseeable future - it is a real risk even without people blowing things up - and we don't yet have a good solution. Research is focussing on using things like aerogel to trap this kind of debris and bring it out of orbit. As long as you can take more debris out of orbit than is being created, you should be able to prevent a chain reaction. But for the moment there is no solution.
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Re:In other conspiracy-related news... (Score:5, Insightful)
I would envision the threat scenario of the Chinese threatening the US in any significant financial way would go like so
1. China: We are cancelling all our loans and investments and want our money back now.
2. US: No.
3. China: Ummm
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