Satellite Shoot Down

[sdennison]

http://www.msnbc.msn.com/id/23166344/

Ok tactical jet fighter jock types, how is this going to work? Randy et al, brief us on this mission if you were conducting it. I'd think we can only intercept over our airspace, no?

Intercept speed? What is the relationship between the interceptor and the interceptee? Do you take on a closure attitude, head on? Just get within 30 miles, vertical or otherwise?

Sorry, I think it's an interesting tactic. Wouldn't the SDS do the trick, if it exists?

Thanks for the replies...

[CAPFlyer]

Well, if it was me, I'd pull an ASAT out of mothballs, put it under Randy's bird and take care of it that way.

But SDS doesn't have the required range to handle this one where they want to. Ideally they're wanting to catch the satellite right at or just before atmospheric interface (where the atmosphere begins to get thick enough to exert real friction against the satellite) because once it reaches AI, then it will begin to tumble and be extremely difficult to hit. With the SM-3 missile, it was designed to intercept an ICBM or TBM at this same point in it's trajectory, so the idea is to make this basically the first operational test of the system after successfully testing in previous years against other, smaller satellites and dummy warheads.

I think it's their best shot with where AI is going to occur. If the SM-3 doesn't get it, then about your only backup with the re-entry trajectory is going to be a PAC-3 shot, but that would be very dangerous because the debris would probably still fall on populated areas.

I do think it highlights the need for the US to have a viable anti-satellite system that allows it to intercept and destroy any disabled satellites and/or other spaceborne objects of satellite size (like spent rocket boosters) if their re-entry trajectory threatens populated land or other "sensitive" areas which the government would not like to have debris impacting on (like natural landmarks, parks, and preserves).

BTW, more info on the SM-3 can be found here - http://www.globalsecurity.org/space/systems/sm3.htm

[B17news]

I don't like the fact that they are filling up the lower orbit with space junk that will eventually hit something important.

B

[Kyleb]

I don't like the fact that they are filling up the lower orbit with space junk that will eventually hit something important.

B

If you hit the satellite when it is in the last few days of orbital decay, won't those little pieces decelerate faster than the satellite would have, thereby falling from space relatively soon?

[chico]

Ok tactical jet fighter jock types, how is this going to work? Randy et al, brief us on this mission if you were conducting it. I'd think we can only intercept over our airspace, no?

Intercept over "our" airspace is unlikely. The idea is that if anything heavy is left, it should come down on the 70+% of the world that's covered with open ocean. If it gets "shot down" that, or any other means of shoot down, will probably happen well out over the pacific, depending on how low the satellite gets before it's brought down.

Adding more junk to LEO is my concern as well. When you've got paint flakes cruising along at 13,500mph and leaving chips in the space shuttle, just think what added left over bits of satellite will do. Here's hoping we can pop it once its sunk low enough that it'll decay fairly quickly.

[B17news]

I don't like the fact that they are filling up the lower orbit with space junk that will eventually hit something important.

B

If you hit the satellite when it is in the last few days of orbital decay, won't those little pieces decelerate faster than the satellite would have, thereby falling from space relatively soon?

in most explosions I've seen, debris goes in all directions, up...and down. With less gravity and atmospheric resistance to deal with, those fragments will go a long way up (and down).

B

[engguy]

Yeah briliant, just what we need some more dangerous and highly toxic Plutonium debris coasting around up there.

[Kyleb]

I don't like the fact that they are filling up the lower orbit with space junk that will eventually hit something important.

B

If you hit the satellite when it is in the last few days of orbital decay, won't those little pieces decelerate faster than the satellite would have, thereby falling from space relatively soon?

in most explosions I've seen, debris goes in all directions, up...and down. With less gravity and atmospheric resistance to deal with, those fragments will go a long way up (and down).

B

Realistically, arn't the only things that will stay in orbit longer pieces that are accelerated into an orbit with a higher perigee? Is that possible in this scenario? I can see how a missile impact could cause the debris to have a more elliptical orbit with a higher apogee, but the perigee shouldn't increase to anything higher than the satellite's existing perigee.

Presumably, since the satellite is pretty low anyway and the perigee won't be higher than the intercept point, shouldn't the small(er) pieces should come down pretty quickly?

[B17news]

I don't see how it *couldn't* have a higher perigee, since the explosion from the missle will blow debris in all directions from the impact point.

B

[RickH]

The missile isn't supposed to have a warhead.

[B17news]

The missile isn't supposed to have a warhead.

wouldn't the hydrazine be volitable enough to not really make a difference?

B

[RickH]

Had lunch today with one of our guys who had just got out of a NASA meeting regarding this very issue. He said that the hydrazine is frozen solid it will vaporize as it heats up. They expect to hit the satellite and all of the pieces would fall into the atmosphere within a few days at most. It aint gonna happen until the shuttle has recovered.

[CAPFlyer]

I don't see how it *couldn't* have a higher perigee, since the explosion from the missle will blow debris in all directions from the impact point.

B

No. You're operating under a lack of acceleration and movement in other directions. First, since the impact would happen close to Atmospheric Interface, there is already a not-insignificant amount of friction acting upon the satellite which would serve to resist acceleration by any debris. Second, since the satellite is moving forward, any debris moving "higher" from the satellite would still have tangential movement "forward". As such, it would still be moving into the direction of friction (against the atmosphere) resulting in deceleration and canceling out much of the additional kinetic energy created within a few minutes of impact. As well, because of it's low altitude, any debris not immediately reigned in will most likely re-enter the atmosphere within months again because it's still in contact with the upper atmosphere. It is extremely difficult to maintain a stable orbit without constant boosting under a 100 mile orbital altitude. As such, most items that are "released" or decay to such a low orbit tend to reenter the atmosphere fairly quickly. The concern over "low orbit debris" is for objects that are in orbit between 100 and 200 miles orbital altitude. This is where many of the early generation satellites and boost sections reside. Taking those out is difficult with any existing system as they're designed to engage ballistic missiles which have an apogee of somewhere around 100 miles.

[Canso42]

Hang a couple of Sidewinders on a Blackbird!

[B17news]

I learned something new today. Awesome!
B