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US Claims Satellite Shoot-Down Success
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?
The US government has now tested it's anti satellite missiles without looking like complete hypocrites for criticizing China for the exact same thing.
There was no need to show off, we had already shot down a satellite in 1985. The big difference here is that we did this one from the ground. Good job!
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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prior to this the maximum ceiling of the missile used was unknown. They now know it can leave the earths atmosphere. Even our own media was under the idea it would take up to 5 shots before a missile directly hit... we did it in 1.
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You may be claiming that it's demonstrably false, but you haven't successfully demonstrated it. And unless you're a materials engineer with access to technical drawings of the satellite and a good simulation of its reentry profile, you're not going to.
You're clearly making huge hand-waving generalisations about something which you don't have the slightest clue about. As usual.
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Weapon systems capable of shooting down a satellite is nothing new. The US and the USSR explored using nuclear tipped missles in the early 60's that could get close enough to a satellite to bring it down. Several countries experimented with high powered lasers as a method of disabling or destroying satellites. The Soviets experimented with so called "Killer Satellites" that would take out a target with the orbital equivalent of a giant shotgun. Since the mid to late 80's, the US Air Force has had an ASAT(Anti Satellite) missle called the ASM-135 that was fired from a F-16 at extreme altitude and would seek out and collide with its targets as opposed to exploding near them.
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.
No, not exactly. Satellites have highly circular orbits - this keeps them at a maximum distance from the Earth at all points of the orbit, and hence keeps atmospheric drag to a mimimum.
To increase the altitude of a sattelite, you need to do two burns - the first burn accelerates the satellite in the direction of it's orbit. This produces an egg shaped orbit, known as a transfer orbit. The round end of the 'egg' is near the Earth, and the pointy end is the point the furthest from the Earth. When the satellite subsequently reaches the pointy end, a second burn is executed, that makes the orbit circular again. I don't remember exactly what the vector of this burn has to be (a tangent to the circular orbit of that altitude I think...), but anyway, the idea is that you use energy to raise the average altitude of the orbit up to the highest point of the transfer orbit. It normally takes several burns over several orbits to achieve a highly circular orbit.
Disclaimer: Take all of this with a grain of salt. I'm not involved with the space industry. It's just that I wrote a game a while back where you are in a space ship protecting the earth from a hoard of attacking satellites that were bombing the Earth. The game was like good ol' Asteroids, you spin left, right, shoot and accelerate. But the thing was, both the satellites and the space ship were in orbit around the Earth, and I modelled gravity. What I just explained above was the technique I used as the player to raise the altitude of my ship's orbit...
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) 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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The fact that the missile used shot down a satellite does not mean that the purpose here was to see if we could shoot down a satellite. Look here...
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.
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