US Claims Satellite Shoot-Down Success 616
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?
in other news (Score:5, Interesting)
Re:Wasn't that the whole point (Score:4, Interesting)
pic of success? (Score:2, Interesting)
Re:In other conspiracy-related news... (Score:3, Interesting)
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.
Comment removed (Score:4, Interesting)
Re:Wasn't that the whole point (Score:3, Interesting)
Still wanna try to claim that tank would survive reentry?
It could be worse! (Score:3, Interesting)
It could be worse:
Here is a video (Score:2, Interesting)
http://www.youtube.com/watch?v=sfk2m60z9EI [youtube.com]
Re:priorities? (Score:3, Interesting)
Re:It's not about hydrazine- and it's not new. (Score:3, Interesting)
Using the sat to test the SM-3 anti-missile saves millions as the sat is useless & an target platform will not need to be expended.
Yeah but China, Russia can't do it from a boat (Score:1, Interesting)
Re:priorities? (Score:2, Interesting)
Re:Wasn't that the whole point (Score:4, Interesting)
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.
Re:Wasn't that the whole point (Score:5, Interesting)
Re:Yes they expect them to fall out of the sky... (Score:3, Interesting)
It's funny to think that it's basically the same technology, although the wiimote uses MEMS [wikipedia.org] accelerometers instead of high-precision gyroscopes (hence the error is way larger)
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.
Re:Wasn't that the whole point (Score:3, Interesting)
Second, even if the tank didn't melt, it would still undergo structural failure at some point due to the terrific pressure hydrazine would generate at those temperatures. And as soon as the containment failed, the hydrazine would begin to decompose. Since it is a monopropellant, it wouldn't need the presence of another gas for this reaction to commence, and the entire tankful would break down in short order.
Re:What's the big deal? (Score:3, Interesting)
Re:Wasn't that the whole point (Score:3, Interesting)
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...
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.
Re:Wasn't that the whole point (Score:3, Interesting)
Re:Wasn't that the whole point (Score:3, Interesting)
Re:Wasn't that the whole point (Score:3, Interesting)
Standard procedure is hose them off outdoors, then send them to hospital for checkup. I never met any troops who were sprayed and expressed any symptoms.
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:3, Interesting)
Well, cost is a valid argument.
Public sources put the cost of the shot at $40-$60 million. [cnn.com] In DoD funding terms, that's pocket change.
To my mind, the more amazing thing is how fast the Navy got the systems involved modified to track and kill a target the weapons weren't originally designed for. Talk about agile development!
Re:Wasn't that the whole point (Score:3, Interesting)
To be more specific: the transfer orbit [wikipedia.org] is an ellipse (as are all orbits. Circles are just ellipses with an eccentricity of 0), which is similar to an egg, but more symmetric.
And you are completely correct about the important bit: Any delta-v burn performed as an impulse (as in, short duration, like an OMS burn or an explosion. Electric propulsion has more complicated rules) will change the orbit, and the new orbit always* passes through the point at which the burn was performed.
*except escape trajectories or certain (N>2)-body problems, but neither of those are really orbits, and they're not particularly relevant in the case under discussion.
Re:Wasn't that the whole point (Score:2, Interesting)
Damn Lies and True Lies (Score:1, Interesting)
So what lies were told?
Was there a sat in orbit? - Confirmed something in orbit by outside observers
Was this a billion dollar spy sat or just left over junk planned for target practice?
Was this a known bad launch vehicle just tossed up as a target?
Was this an old sat intentionally moved to this lower orbit to use as a target?
Was it hit by the missile or was this all theater?
Did the sat have a self destruct and the missile mis it by a mile like one of the former tests?
Was this some show to cover some stranger event such as launching to orbit from sea?
They made a show of this for a reason!!!
[tin foil hat = off]