Are some smart weapons a dumb idea?

[unixronin]

No, bear with me here for a moment.  We all know that one round, on time and on target, is worth more than a battery twelve half an hour late and five miles down the valley.  But one thing I've been noticing lately is that more and more, the US is moving toward GPS targeting for precision-guided munitions — cruise missiles, tactical surface-to-surface missiles, even artillery shells.  And I'm not at all sure this is a good idea.

The good part of this is that, if the GPS system is working, all these weapons become capable of reliably striking within a few feet of their targets, so long as you know with good accuracy EXACTLY where the target is.  But the key part of that is the clause "when the GPS system is working".  The recent Chinese ASAT test makes two things very clear — first, that they can kill satellites with a ground-launched weapon, and secondly, that they have no qualms whatsoever about filling up near-earth space with junk and debris.

So consider this scenario.  China makes a move against Taiwan.  The US threatens military intervention.  China fires off a salvo of thirty or so ASATs and splashes twenty or thirty satellites, mostly their own old satellites, in orbits that intersect those of the GPS satellites.  They haven't fired on any US asset, so it's not a directly hostile act against the US.  But over the next twenty four to forty eight days, impacts with debris disable a large proportion of the satellites in that orbital region, including a large proportion of the GPS constellation.  Perhaps if if the debris could doesn't disable enough, they directly fire on several of the remaining GPS satellites, taking out enough of the GPS constellation that there's no longer enough satellites visible at any given time to obtain GPS fixes.

And the US military's entire arsenal of GPS-targeted precision guided munitions stops working.  Suddenly they're not precision-guided any more.  Inertially-guided cruise missiles still work, but GPS-targeted weapons like ATACSM lose the ability to strike their targets.

It seems to be to be a very bad idea to base your entire munitions strategy on a relatively fragile resource that one of your major potential enemies has already demonstrated the ability to disable or destroy.  I sincerely hope the Pentagon is thinking about this.

Comments

[johnkzin.livejournal.com]

IIRC, with laser guided bombs, the guidance system is actually an add-on to the front of a bomb. It can be removed and replaced with a different guidance system. You can unscrew the guidance package from the front, replace it with another, and just hook it into the mechanism that articulates the fins/winglets on the bomb.

I would hope that GPS guided bombs are similarly modular, so that if such an event happens, the obsolete pile of scrap is just GPS guidance modules, and not the entire bomb.

The question then will be "how must dust has been gathering on the laser guidance modules".

Though, I also seem to recall that the GPS guidance is on the BACK of the bomb instead of the front. That, then, makes me wonder if a given bomb can actually be fitted with both guidance systems at the same time.

[lonewolf545.livejournal.com]

You can bet the military is aware that GPS can be compromised or knocked out. Our troops still use plenty of non-precision weapons, they ARE cheaper, after all. But when you CAN use precision weapons, they offer tremendous advantages, particularly when operating close to civilian populations that you don't want to harm.

[unixronin.livejournal.com]

Oh, sure. There's still lots of application for plain ballistic delivery. I'm just concerned that where it comes to PGM guidance methods, we may be putting too many eggs in one basket because GPS is "cheap, accurate, and there".

[mrmeval.livejournal.com]

Latest GPS smart bomb is a glue and go package for the standard iron bomb (or leaflet container, nuke, emergency supply delivery etc.) and it has an inertial guidance system. It's very good with GPS, but does not suck too badly without it.

[unixronin.livejournal.com]

That's good to know. Glad they didn't go entirely to a single-mode seeker.

[mrmeval.livejournal.com]

http://en.wikipedia.org/wiki/Precision-guided_munition

Reasonably accurate, there are other sources such as global security and you should be able to subscribe to the various defense contractors press releases.

The stuff that's publicly listed is impressive. The stuff that could be possible is pretty staggering but is stifled by the rules, regs, etc.

Orbits

[7leaguebootdisk.livejournal.com]

GPS sats are in medium orbits, 12k miles out, a MUCH harder target than stuff in LEO (a couple of hundered miles). There is lots in LEO, a little in geosync orbits, and very little in between.

Re: Orbits

[unixronin.livejournal.com]

It's harder, yes. But is it really that much harder, for a nation that's declared its intention to put taikonauts on the Moon? If they can kill a target satellite in LEO on their first try, I wouldn't put the GPS constellation out of their reach in the next five or ten years. We put'em up there, after all, and they have the benefit of a great deal of what's been learned since then.

(And frankly, who knows what else the Clinton White House sold to China....)