Wednesday, April 10, 2013

Missile interceptors and you

North Korea has continued popping crazy pills at an astounding rate. Their latest move, it seems, will be to fire (or test-fire, as in, not at an enemy target) a medium-range missile or two from its east coast. This has everyone a little nervous, because if even if the thing flies perfectly--and they don't always work out that way--it could very well fly over or land near Japan.

A brief look at what the DPRK is bringing to the table: The Musudan ballistic missile.

Pointy? Check. Fins? Check.

With a range of a little over 2,100 miles, it could concievably hit all of Japan, bits of Russia, a scattering of U.S. island bases and of course China. (A Co-Worker of the Blog suggested hitting China would be North Korea's ultimate "look at us, we're so crazy and unpredictable!" card.) It can theoretically carry a 1,600-pound warhead. I say theoretically because it has not been successfully tested.

Meanwhile, South Korea, the United States and Japan have brought their own pointy-finned toys to the table. In Japan, you have the MIM-104F Patriot PAC-3 deployed around Tokyo.

It's in a box, but yes--pointy and finned.

These are the latest iteration of the Patriot air defense missile made famous--or infamous--in the first Gulf War. These days, they are lighter, faster, stronger and have a tougher job than their predecessors. The early Patriots were designed to destroy their targets by exploding nearby and spraying it with high-velocity fragments. The idea is that this structural damage would rip the target, also traveling at high speed, straight to pieces.

But there is a better way: hitting it directly. Until relatively recently, the idea of hitting a missile directly with another missile was too difficult an engineering challenge to pull off reliably--thus the blast-fragmentation warhead. But the PAC-3 is in fact designed to hit its target directly. It does this by combining high-quality radar data from ground stations with a radar receiver in its own nose (now conveniently empty of a large warhead). When it hits its target, the kinetic energy of two objects, each moving about five times the speed of sound, is enough to completely obliterate the incoming missile... and thus prevent its warhead from following a ballistic path and hitting something on the ground. To make sure the job is done, the PAC-3 also carries a small explosive charge.

Meanwhile, in Korea and Guam, you have the latest in missile-blowing-up technology, the THAAD, whose unwieldy acronym stands for Terminal High Altitude Area Defense. It looks a little something like this:

Yep. Another box.

The THAAD is designed to actually destroy an incoming ballistic missile at the edges of the Earth's atmosphere, essentially before it has time to begin falling toward its target. This is a fantastically tricky task, and the actual interceptor is studded with reaction control jets that make it look like a freaky alien spaceship:

And that weird-looking box smashes into the warhead, again using kinetic energy to blow the enemy missile up real good.

And finally, both the U.S. and Japan have ships loaded with RIM-161--the boringly named Standard Missiles--that can actually blast satellites out of orbit.

Pointy again!
As the link above illustrates, these missiles, in combination with the U.S. Navy's Aegis radar system, are designed to hit incoming warheads well away from the target. This includes ICBMs, which thankfully North Korea has none of, but also shorter-range ballistic missiles. And like the THAAD and PAC-3, they are designed to directly hit their targets.

The exact ranges and capabilities of these systems are played relatively close to the vest. The Patriot's ground-based radar has a range of 65 or so miles. The THAAD and RIM-161 are harder to pin down, but as their targets are essentially extra-atmospheric, we're talking hundreds of miles, most likely.

What does this all mean? Well, essentially, it means that barring multiple failures--not impossible, but unlikely--if North Korea shoots a missile... and it works... and it's headed anywhere remotely dangerous... it will probably be shot down by one of the above systems. But in the meantime, let's hope for a sure thing: if North Korea doesn't test its missile, no one will get hurt.

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