US To Shoot Down Dying Satellite 429
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.'"
Our secrets are worth more than your secrets! (Score:5, Insightful)
Is this really anything else? The US is willing to protect it's secrets, China was trying to ensure they could protect theirs. Both are sovereign nations with the technology and ability to make these decisions.
The only way issues like this will ever be resolved is by allowing some intra-national body to have either approval or veto powers, but nobody wants to be told what they can/can't do.
Re:Our secrets are worth more than your secrets! (Score:5, Insightful)
That may be the actual thought process at the Pentagon, but there is actually a sound justification for shooting down this satellite: TFA says there is a 1 percent chance debris could hit a populated area. That is well above the danger threshold NASA, etc. allow when choosing where to perform a controlled deorbit. 1 percent doesn't seem like a lot, until you realize how many satellites are up there, and they all must come down eventually.
Even if safety weren't a genuine concern, it would still be acceptable to shoot down this particular satellite, in my uninformed opinion. I believe this because it's already in a decaying orbit that will bring it down within two months. Any debris created by the explosion will be in a similar or slightly higher orbit, and will also decay to GLO (ground-level orbit) in a reasonably short time. The satellite the Chinese shot down was in a much higher orbit, and that debris is likely to stay up for *hundreds* of years, IIRC. If they had shot down a satellite in a similar orbit as this, there wouldn't be a stink about the debris, only about the naked attempt at weaponizing space.
China's debris to remain for thousands of years... (Score:5, Informative)
The two shoot-downs are not equivalent, which of course won't prevent agenda-driven comparisons...
Still dangerous (Score:5, Insightful)
Letting the satellite re-enter atmosphere unbroken would be the only way to make sure it does NOT create a debris field.
A satellite is not an airplane, there's no way to "shoot" it down. Breaking it in pieces will not bring it down, it's atmospheric drag that's doing it. All the Pentagon is doing is trying to make sure that it breaks down into pieces small enough to protect their military secrets.
By blowing up the satellite with a missile they have no control on how it's going to break, all they can do is estimate on the most probable breaking patterns. They cannot be sure that the remaining pieces will be of such sizes and shapes to re-enter the atmosphere in a predictable manner and time.
There is still the possibility that some of the largest fragments will hit some populated area. The fuel tanks, which are compact and very strongly built, will have a rather good chance of surviving, and reaching the earth's surface still containing some of that extremely toxic hydrazine (so toxic that a drop can kill a person). Besides, the explosion will inevitably send some fragments into a higher orbit, and possibly damage other satellites.
Blowing up a decaying satellite with a missile is, IMHO, the stupidest thing to do, and I have been an engineer working with satellite control systems for nearly 24 years by now.
Re:Still dangerous without the shot? (Score:5, Informative)
Yes, they would. People on the ground will always be at some danger when you put an 11-ton satellite in low earth orbit.
But it's easier to predict the impact point of a body that has a well known shape and orbit than that of a body that has been torn apart and pushed in random ways by an explosion.
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You can minimize the danger if you inflict a sudden loss of momentum on the satellite such that it will come down in an unpopulated area, such as an ocean, with a high degree of predictability. If you can at the same time destroy the satellite's tank, which contains a highly poisonous substance, all the better. If you just let it come down on its own, it can come down anywhere (equat
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Re:Still dangerous (Score:4, Informative)
Sure, but how hard can you hit? It's not as if it were hitting a stone wall, it's hitting an exploding missile, that is, a fire ball. It's travelling at close to 8000 meters, or five miles, per second.
The densest parts, like batteries, fuel tanks, and possibly the main camera mirror, will go through that explosion ten times faster than a bullet. Do explosions stop bullets? Not unless it's precisely concentrated at the exact point [wikipedia.org]. There is no way the explosion could transfer enough momentum to the densest parts to significantly affect their orbit.
The flimsiest parts like, for instance, the solar panels, will be shredded to very small pieces by the explosion, of course, but those are exactly the parts that would burn first when entering the atmosphere.
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Re:Still dangerous (Score:4, Interesting)
Since you've got 8 km/s of orbital velocity and probably around 3 km/s on the interceptor, you're probably talking about 10 km/s at the intercept. The heat of vaporization of iron is 250 kJ/kg and this thing has a mass of 11 tons, so we can assume 2.7 GJ will do quite a number on this satellite. Sure, it's not made of iron, but you don't really need to liquify it to destroy it. Satellites are usually only built to survive launch stresses, not impacts.
Anyhow at an impact velocity of 10 km/s 2.7 GJ would require a impactors with a total mass of 50 kg, probably in the form of lead or depleted uranium for compactness. To be thorough in your destruction, you probably want multiple small impactors, say 500 of them at 100 grams each. The total mass of the warhead depends upon how close you can get to the target. If you could be ensured a direct hit, 50kg would suffice. But it's likely that this won't be a direct hit, so you'll need to cover a larger area than the satellite itself.
We'll assume the satellite projects an aspect of 600 square meters (say about 60 meters by 10 meters) and that our shot cloud covers a circular area. Once your impact parameter exceeds 14 meters your warhead size goes up as the square of the distance. At 25 meters, you need 160 kg. At 50 meters you need 650 kg. At 100 meters you need 2.6 tons. At a kilometer you need 260 tons.
The only thing determined by the yield of the charge that scatters these impactors is the timing. How long before impact do you need to set it off and how accurate does your timing need to be? These are left as an exercise for the reader. If I were designing the thing I'd keep the scattering charge as small as possible. The bulk of the constraints are set by the trajectory. In a head on trajectory, there is nothing wrong with scattering the impactors 5 seconds or more before impact. For an interceptor that travels vertically, the maximum timing probably depends upon atmospheric properties.
Given the geometry of the likely impacts, it is unlikely there would be significant amounts of ejecta inserted into long lasting orbits. The worst cases would be insertions into elliptical orbits, but they would circularize quickly at low altitude due to the low perigee. It should be possible to choose in impact point that will minimize risk to other vehicles.
FWIW, I do not design space weaponry, and I do not know the actual capabilities of U.S. anti-satellite weaponry. I just know how to break things in a practical and sometimes dramatic manner.
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What goes up must come down, eh?
Nope.
It depends entirely on the radius of the orbit, the orbital velocity, and the amount of upper atmosphere remaining at that altitude. If the orbit is good and the drag nil, it'll stay up there. Or at least that's how orbital mechanics worked when I was a kid.
Re:Our secrets are worth more than your secrets! (Score:5, Insightful)
Re:Our secrets are worth more than your secrets! (Score:5, Insightful)
To be fair, the space junk isn't equivalent -- the junk from a satellite that's about to reenter will also reenter promptly, whereas the junk from a satellite in a high orbit will remain in a high orbit. The impact won't actually alter the orbital parameters of the junk as much as you might expect; nearly all of it will reenter promptly, and I'd be surprised if any of it managed to get high enough to present a danger to other satellites (the satellite in question is well below normal operating altitudes).
Of course, I'm not trying to say the US isn't guilty of hypocrisy -- just that this case isn't as bad as you make it out to be.
Re:Our secrets are worth more than your secrets! (Score:5, Insightful)
Such as telling certain countries they are not allowed to have nuclear weapons while allowing, and even encouraging, others to do so. Or telling certain countries they cannot have wmds in general and then invading that country to prove they don't have any. Or did you mean not trading with a country until it changes its political climate?
You mean a world dictatorship telling soverign nations what they are permitted to do like that, right?
Target practice or....? (Score:5, Interesting)
Re:Target practice or....? (Score:5, Interesting)
A bit of both I suppose. It's not every day you get to do a live-fire exercise of your satellite-attacking technologies... Not to mention it's not every day you get a real live test of just how good your satellite's anti-missile technologies are! Either way somebody in the military wins :P
Big chunks will no doubt re-enter the atmosphere relatively quickly, and they should be small enough that they will burn up completely in upon re-entry, which I think was the whole point of this exercise...
Re:Target practice or....? (Score:5, Interesting)
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Of course this being the USA Military I expect military intelligence to kick in and they send up 5 missiles more than they need to.
Re:Target practice or....? (Score:5, Insightful)
The US military is probably aware of the max velocity of debris from their different ordinance. As much as the US administration is full of morons, the physicists designing the ordinance and planning stuff like this are quite competent.
Re:Target practice or....? (Score:5, Funny)
Just to be a smartass, I have to point out that the volume of a circle is zero, not pi*r^2.
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Chances are it would fall back to earth fairly quickly.
Re:Target practice or....? (Score:5, Informative)
Longer answer: The orbit of a satellite can be determined by the position and the velocity at any time. Orbits are changed by changing the velocity of a satellite, but the old and new orbits will continue to intersect at the point where the velocity was changed.
Changing to a higher orbit will require two changes in velocity and uses a transfer orbit that intersects both orbits. One velocity change puts the satellite into the transfer orbit and one velocity change puts it into the final orbit. Usually, the two velocity changes are at opposite sides of the transfer orbit (half an orbit period apart).
I assume that this will use a warhead instead of a rocket motor for a single change of velocity, but there will only be one change of velocity. If the intercept takes place at lowest point of the current orbit then any debris will be in an orbit that will return the debris to the point of intercept. If it is already brushing the atmosphere then reentry is inevitable and the time to reentry will only depend on the ratio of the mass to air drag of the object (small heavy objects will stay in orbit longer).
Normal precautions of staying out of the temporary orbits of the debris does apply.
_Richard
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Or target practice?
Don't underestimate the value of target practice. Shooting down a satellite is no simple matter. The Chinese engineers decided that they couldn't just hit one with a missile, so they sent up a missile capable of firing a separate payload once it got close enough. I'm sure the US would love an excuse to try out a satellite killer. And, since it's been made clear what a hazard this thing could be if it falls to earth, they can try out their new toy AND protect the planet from their defunct satellite.
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In an way, it is an opportunity for a US response to this: http://science.slashdot.org/article.pl?sid=07/01/18/0235229 [slashdot.org]
The thing is, you do not want "pollute" your (everyone's actually) orbital pathways around earth with millions of pieces of high-velocity debris like the Chinese irresponsibly did here: http://www.theregister.co.uk/2007/01/19/china_satellite/ [theregister.co.uk]
The Chinese dramatically increased debris in several orbital pathways from the state-sanctioned shoot-d
Re:Target practice or....? (Score:4, Funny)
Ulterior motive? (Score:5, Insightful)
Re:Ulterior motive? (Score:5, Insightful)
That, or there's some technology on the satellite that they don't want to risk falling (literally) into the hands of another country.
Re:Ulterior motive? (Score:5, Insightful)
A. If push comes to shove they want to be able to shoot down emeny satellites.
B. They don't want the technology/information going to an other countries hands.
C. To show that we can, prevent other people from knocking out our own satellites.
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Re:Ulterior motive? (Score:5, Interesting)
And from TFA (again, emphasis mine):
It doesn't seem as if "shooting down" the satellite is really going to cause much more damage than re-entry and impact will...for this reason, my money's on either target practice for our benefit, or, more likely, a not-so-subtle demonstration of our space superiority.
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And, we can (sorta) choose where the pieces come down, instead of relying on mere chance. My guess is they'll bring it down over the ocean.
Major differences (Score:3, Interesting)
Keep in mind, that America (as does Russia, China, UK, France, and others) de-orbits spy sats regularly. There have been
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Who cares? Wasn't the damn thing broken [tech-archive.net] to begin with?
Re:Ulterior motive? (Score:5, Interesting)
Heh, or not. One of the things Britain did during WW II was to leave bits of busted machinery (electronics) that not only never worked, but were designed to be deliberately misleading, at the occasional aircraft crash site in German-occupied territory. The idea was to keep German radar scientists, etc, busy chasing down wrong paths if/when they recovered the equipment. (Which they did; recovering any kind of radar-related gear from Allied aircraft was a high priority for them.)
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The 'tech on the satellite they don't want falling into ot
Re:Ulterior motive? (Score:4, Insightful)
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As opposed to the US, which has brought so much good to the world lately, I guess.
(By the way, China is as communist as the US is a free market...)
It's far less sinister than that... (Score:2)
Ballistic Missile Defense (Score:5, Insightful)
The program has been in the development and test phase since about 2000, and undergoing tests of increasing difficulty, but always under predefined conditions. The tests are also expensive to orchestrate, typically involving several naval vessels, and a lot of ground support from both the navy and contractors, a lot of documentation, and a target missile that itself probably costs several million dollars. Here they've got a target that won't behave as predictably and costs nothing (well sort of...It's a spy satellite that failed to reach the proper orbit). I'm not sure they even know when or where it will come down yet.
This isn't necessarily a good demonstration of our ability to shoot down satellites. The officially released specs say it has a maximum altitude of 160 km. Most satellites orbit higher than that. However, the actual performance is classified and probably somewhat greater.
It's also not something new. We tested anti-satellite weapons in the 80's, although those are now past their shelf life and the response time was slow. In the 60's we developed a system called Nike Zeus that had an altitude ceiling of about 300 km. It wasn't accurate enough to directly hit a ballistic missile or satellite to achieve a kinetic kill like the SM-3 does, but with a 40 kiloton nuclear warhead, that didn't much matter. It was never tested with a live warhead and it would have been messy to use (damages anything else nearby, terrible EM interference on the ground, etc), but it was something.
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Re:Oh bullshit. (Score:5, Interesting)
The reson we are doing this is obvious - to demonstrate to the world (and the Chinese) that was have functional ASAT capability.
I think the reason is more because various agencies are worried that the satellite will end up falling in someplace while Russia or China and the intact pieces will give these countries examples to reverse engineer or clues as to US capabilities. I believe the satellite is supposed to be the newest generation of spy sats so it's probably full of interesting little tech.
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Or, we have a self-destuct system and one of it's requirements is communication with ground.
In that case I guess I'd have liked to of seen some built in structural weakness. Some sort of failsafe so that if the satellite were to re-enter the atmosphere and begin to burn up, some ignitable material would ensure a thorough burn/destruction of the
Re:Oh bullshit. (Score:4, Insightful)
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Re:Oh bullshit. (Score:5, Insightful)
It's a brand new spy satellite that failed on deployment. It's chock full of the highest tech we could stuff in it.
I'd blow it up too if it was mine, there's a crapload of technology that even after reentry would be of HUGE value to many many people on this planet.
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It's in a degenerate enough orbit to not cause any lasting space debris. We've done this before successfully, and we're going to see if we still can.
no, it's not the hydrazine (Score:5, Insightful)
As for the PR damage of killing whoever comes across the fuel, after the whole Iraq war thing, I think it can be conclusively and uncontroversially stated that one thing the Bush administration doesn't give two shits about is bad PR.
Hey, how about making a film about this?? (Score:2, Funny)
Simple enough (Score:2, Funny)
The Winner gets to choose when and where to shoot the missle
I can imagine that conversation (Score:2, Funny)
Bush: 'kay
Military: It poses no real threat, it will probably burn up on reentry...
Bush:'Kay
Military: It was a secret spy satellite...
Bush:What? Spy?
Military:It will look real pretty if we blow it up sir...
Bush: OooOooOoo Pretty... Kay, where do I sign to see the pretty boom boom?!
You've gotta admit... (Score:2)
And I'd probably have a similar response to your hypothetical Bush... muhahaha... boom boom!
In other news... Dead Horse Mercilessly Beaten (Score:2, Funny)
Not the same as Chinese Test (Score:5, Interesting)
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Er, didn't some unscrupulous people put the damned thing up ther ein the first place? I mean, us?
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As for the fuel, I expect you mean plutonium. No propellant is going to make it to impact. So the question is - do you want to spread very small concentrations of plutonium over a wide area where you can't clean it up or have to go find a few concentrated dollops after impact, like they had to do in Canada.
Seems rather like the Quentin Crisp approach to re-entry management to me. Don't lose your nerve - after 5 reentries it won
Controlled de-orbit? (Score:2, Interesting)
There is far too much space junk up there already. Blowing the satellite into a million pieces doesn't seem like the smartest thing to do. I suspect the US simply wants to demonstrate and test its own anti-satellite system.
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The problem with your idea comes down to it being far too complex of a process for the intended result. Launching a rocket to match up with another satellite is much more difficult than in sounds. The bottom line is that
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Because that's a lot harder. If all they wanted was for it to deorbit, they wouldn't be doing anything -- the satellite in question never reached its final orbit, and is rapidly decaying. It will reenter fairly soon if left alone. Presumably they're trying to prevent it from reentering where Russia or China or someone might find the pieces and get clues about our capabilities -- it's pretty clearly a recent-generation spy satellite. If they are careful about how they shoot it down, they may get some con
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let this be a lesson to NASA/JPL (whoever) (Score:4, Interesting)
Re:let this be a lesson to NASA/JPL (whoever) (Score:4, Informative)
Unless of course, the satellite stopped working because it's computer is bust. Then you'd have a big lump of explosives rolling around in space, and no control over it.
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And what of those other ideas? (Score:2)
How about a disintegration ray? (Score:2)
thats right, my disintegration ray would sound like a toy gun you can find at the dollar store.
Maybe instead they should just find a way to push the satellites out of orbit into space maybe even toward to sun for future disposals? Otherwise we're gonna need to come up with either much stronger material to not get damaged by space debris, or make some big magnet that can scoop it up out of orbit.
They are spinning the media with a scare story (Score:3, Interesting)
Looks like a great chance for the Bush regime to pull off an ASAT test, with a ready-made cover story to deflect blame for all the space junk it will create.
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rj
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The US has had ASAT technology for decades, which is why the Russian Navy has equipped its ships with shortwave radios.
Cost Effectiveness. (Score:5, Funny)
You know, if the pentagon REALLY wanted to come across as bad ass, they wouldn't have told anyone it was a bad satellite. Then we could show the world we'll shoot down our own satellites just cause we can. Like a diplomatic "Don't you know i'm locco, esse?"
I wonder (Score:2)
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Option 5: option four plus some shit we slashdotters haven't thought of
Shooting it down? (Score:5, Funny)
That makes a better headline anyway, "US To Shoot Up".
Why demonstrate ASAT? (Score:2)
If it is a matter of scaring their "enemies"*, they already have enough to be scared of... and they still cause trouble. If the test is successful, why give them a demo of what you would actually do so they have real world ideas of how to make counter-measures?
*enemies the US really has to worry about couldn't make a sputnik with prese
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All the simulations in the world aren't worth 1 actual shot. And it's quite hard to keep a shot like this secret.
Am I the only one... (Score:2)
-Goran
Once gain - tinfoil over facts (Score:5, Insightful)
This is very unlikely to add to the space junk problem - because this bird is in a decaying orbit. You further reduce the chances by waiting as late as possible (when the bird has been greatly slowed). You further reduce the risks by arranging your intercept geometry such that few (or no) pieces are boosted towards or into stable orbits.
It's not nearly as simple as "oh n0es, bl0w1ng stuffs up 1n spac3 m3ans mor3 spac3 junk !!11!!!1111!!111".
I often wondered (Score:5, Funny)
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I guess that's why they can't use the thrusters. I wonder how much this piece of junk cost, and how much money was taken from health care and education just to fund it. Why repair it when we can show other people how we blow stuff up?
So, would you rather take another $1.8 billion dollars to have the same incompetents build a satelite repair-robot or just take a few dozen million and risk the setback of loosing a shuttle while having the same incompetents try to catch the thing in low earth orbit and bring it safely back to earth? Personally I think we should just launch a little satelite with big thrusters and a grapple of some sort to glomp onto the defective uuber-satelite and adjust its orbit so it'll land on US soil, but what do
Re:Incompetent (Score:4, Informative)
Kind of hard to do that when the master CPU fails on boot-up, which is the whole reason why something needs to be done about it. It is literally out of control.
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Re:Incompetent (Score:5, Informative)
Re:Incompetent (Score:5, Funny)
Orbit Pollution (Score:2, Funny)
Wonder how long till Al Gore's next book?
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Apparently, we do. And it's from a cruiser, not a carrier.
I know an ASAT weapon was launched from an f16 (i think)
F-15, firing an ASM-135 [wikipedia.org]
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...or they could calculate the trajectory of the satellite as it is, figure out where it would land with its current momentum, and then shoot something to collide with it to make it land somewhere in the U.S.
And here I though the aerospace industry was full of physicists....
Mg (Score:2)
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Both the original ASAT system and the Aegis are only useful for low orbiting targets. So it's probably more useful to have it as part of a theater defense setup more than something you need to have enough warning to launch an F-15 at.
But, yah, the s
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So yeah...err..totally different (and i'm not American, so I'm not defending my own nation or anything).