USA 193 Shootdown Set For Feb 21, 03:30 UTC 358
An anonymous reader writes "Amateur satellite watcher Ted Molczan notes that a "Notice to Airmen" (NOTAM) has been issued announcing restricted airspace for February 21, between 02:30 and 05:00 UTC, in a region near Hawaii. Stricken satellite USA 193, which the US has announced plans to shoot down, will pass over this area at about 03:30. Interestingly, this is during the totality of Wednesday's lunar eclipse, which may or may not make debris easier to observe."
I wonder (Score:5, Interesting)
Destroy classified items (Score:3, Interesting)
Re:Good coverage (Score:5, Interesting)
http://www.fas.org/blog/ssp/2008/02/us_plans_test_of_anti-satellit.php [fas.org]
Re:Good coverage (Score:5, Interesting)
Re:Moon hiding behind megameters of solid rock (Score:5, Interesting)
Yep, but by the time the debris orbits into the Earth's shadow, about 15 minutes after the impact if my guesstimate is right, it will be entirely dark in visible wavelengths, shining only by reflected light. At that point, the lunar eclipse hinders rather than helps things, by removing a light source. And the eclipse moves out of totality within another 15 minutes after that.
Short version: The timing relative to the lunar eclipse is pure coincidence.
Unless it's a critical part of the top secret plan to propitiate Nyarlathotep and force Great Cthulhu back into an uneasy aeons-long slumber among the cyclopean ruins of R'lyeh, the fabled city of the Old Ones, looming over the black abyssal plain that lies miles below the sparkling sunlit waters of the Pacific.
In which case, I don't want to know what's in the payload of that missile.
Re:Isn't it obvious? (Score:1, Interesting)
This has a different PR ring about it, all trumpets and drums before it happens.
You know what would be really funny, after the puff and bluster, the Americans miss it. (and probably take out a Russian sat by "mistake")
Get a Video! (Score:3, Interesting)
Re:Disappointing. We need to LASER it. (Score:3, Interesting)
Re:Good coverage (Score:5, Interesting)
Re:Good coverage (Score:5, Interesting)
Besides, if it's the gear (rather than the fuel) that concerns them then why haven't they bothered shooting down other de-orbiting sats in the past?
Three reasons (Score:5, Interesting)
- They don't want a repeat of Skylab where parts landed in Australia and made us look bad.
- If it comes down in Russia (Russia spans 11 time zones so that's not too unlikely) they don't want the Russians to be able to figure out much from the debris.
- They want a chance to test their anti-satellite weaponry on a real target that isn't saying "Over here! I'm over here! Here I am! Yoo Hoo!"
There's actually a 4th reason - blowing stuff up is fun but they would never cop to it.Re:Good coverage (Score:2, Interesting)
First, them saying that they're "modifying" current hardware and software to be able to shoot down a satellite is like saying the US army isn't quite capable of shooting down a satellite. Of course they can, and they've been capable for years. This is only proving their homeworks is actually a viable solution, while keeping the public's eye away from military demonstrations. "Yeah we're cleaning up our space, that's right."
Second, it serves no useful purpose to the orbital space whatsoever. The satellite is coming down, as a whole, right now. If no actions are done (saving 60$M in the process), the block of metals and circuits will just crash down somewhere vaguely predictable. Now, instead of one big vaguely predictable chunk of technology falling down, we're going to have hundreds if not thousands of smaller chunks that are going to be absolutely impossible to predict their trajectory. Mir was sent purposely into the ocean (missing the fun target), but it was still targeted there. Now this satellite is going to go wherever it pleases, regardless of our actions.
The only reason this is being done is because they want to protect their satellite from enemy's eyes, and test a defense system in the process. Nothing more. Like I said, the satellite is going down, they,re not "cleaning" anything by destroying it.
As others have pointed out in previous slashdot commentaries, there's even the risk that the explosion might send pieces of debris upwards in the atmosphere, and it may even reach an altitude that will not allow it to fall back down for a very long time. This would have the added bonus of actually putting NEW junk to clog up the orbital space that was previously doing without those new parts.
Re:Self-destruct - standard feature (Score:3, Interesting)
The best thing to do when a satellite needs to be removed from orbit is to de-orbit it with thrusters. Unfortunately, the computer on this satellite flaked completely soon after launch, and the de-orbit system could not be activated.
Re:Good coverage (Score:3, Interesting)
Re:How Convenient (Score:4, Interesting)
So imagine the satellite in a stable orbit. Then you blow it up. So some pieces go flying in all directions. If you work out the orbital mechanics, every one of those pieces will be in a different orbit, but all of those orbits will pass through the point of the explosion. Caveats: this isn't true of orbits that intersect the ground first, or bits that, as you noted, get flung out of orbit altogether - that is, they achieve escape velocity. Escape velocity is awfully fast though, so that's probably not an issue here, and if something does hit escape velocity then it's not going to be a problem for us because that chunk of satellite will be GONE.
That's the reason you can't fire things into orbit with a gun (railgun, whatever), by the way. Any "orbit" you can put it into will have a point intersecting your gun. In order to put something in orbit that way you'd have to fire it out of the gun, then have a rocket on board to fire later and put it into an orbit that doesn't intersect the ground.
You can't actually escape the gravitation of anything, much less a planet. Technically, Earth, the sun, your toothbrush, will all pull on you (very weakly) no matter how far away you get. What you're thinking of is escape velocity, the speed at which you will never fall back, but continue on (slower and slower) outward forever.
Things we send into space can go a few different ways. If it's above escape velocity (Voyager, say) then it will never come back. If it's in a nice high orbit, way above the atmosphere (like geosynchronous satellites) then it will stay up for a LONG time. It will probably eventually come down, because there are always a few stray particles and things, but not for a long, long time. Things on a suborbital trajectory will come back down without circling the planet. Like SpaceShip One. Or you can have a low orbit, like spy satellites and the space shuttle. The atmosphere at that altitude is really thin, but not non-existent, so without thrusters to boost the orbit those sats will come back down, often on a fairly short time scale. The space station is fairly high (and massive) but if I recall correctly, it's orbit will decay in something less than a year without periodic boosting.
The problem with the satellite is that they've lost control. It isn't responding to commands. So it has lots of fuel (hydrazine) but the controllers have no way to fire the thrusters.
As someone else pointed out, orbital mechanics is kind of a counterintuitive thing. You'd think you could shoot things into orbit with a big enough gun, or that blowing up a satellite could boost some bits of it into stable orbits, but it turns out not to work that way. Something else weird: when you thrust in the same direction as you're traveling you slow down. You gain altitude, but you slow down - the opposite of what we normally expect. These satellite bits are speeding up (and losing altitude) due to atmospheric friction.
Lunar eclipse is a red herring (Score:1, Interesting)
Re:In Soviet Russia (Score:3, Interesting)
ago are reverse engineered to make stealth cruise missiles
for the Bear Bombers that recently went back on patrol.
http://www.janes.com/extracts/extract/jsws/jsws0485.html [janes.com]
I have never looked at my shovel so fondly before.
Boiling point of hydrazine (Score:1, Interesting)
Really?
The boiling point of hydrazine is 113.5C (Merck, 1983; CRC, 1994).That is: very low.
I'd really like to now how you can keep a tank inside a molten steel ball at 113C max. I'd even say it's not possible.
Re:Nothing to see here, move along (Score:3, Interesting)
Re:Nothing to see here, move along (Score:1, Interesting)
Re:Good coverage (Score:4, Interesting)
Re:Will a nuclear battery blend? (Score:3, Interesting)
Re:Nothing to see here, move along (Score:3, Interesting)
China's ASAT capability is a really, really big concern to the US military. Over the years, we've let ourselves become more and more dependant on satellite communications to guide our forces and control our weaponry. Yes, we have plenty of other means of communication, but satellite communications take up an increasing share of the traffic, and some systems only communicate through satellite. China being able to knock out our satellites during the opening salvo of any conflict wouldn't pose a fatal situation to our combat capabilities, but it would be a huge blow.
As an aside, one fun ASAT mechanism that a friend of mine who used to work in military intelligence told me about a while back: sand. You launch a missile full of sand into orbit, then detonate the missile with conventional explosives. You get sand moving at tens of thousands of meters per second crossing all sorts of different orbits, rendering space a no-go zone for decades. Of course, we know something like Starfish Prime would do a pretty good job on its own, as well as playing havoc with the electricity grid below where you detonate it.