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The US just pulled off an important missile defense test

Rocket science is hard. Really hard.

Screenshot of Missile Defense Agency video, released today.
US Department of Defense

The US Missile Defense Agency (MDA) just successfully tested a ground-based defense system against an intercontinental ballistic missile (ICBM), ostensibly to ensure that the US can stop threats emanating from Pyongyang or Tehran.

The $244 million dollar test was described as a “very realistic” scenario based on what the intelligence community believes the North Korean or Iranian missile programs might look like in the 2020 timeframe, Vice Adm. Jim Syring, the director of the MDA, told reporters.

Make no mistake: This is a big deal, and a success for the US military as it tries to fend off growing missile threats from the West and East. But even this very good news still comes with a qualification. Mainly, that the test — like most simulations — can never accurately mimic what an actual ICBM attack from, say, North Korea would be like in real life.

That doesn’t take away from the success. It’s just the nature of missile-defense testing. And even when the tests fail, which they often do, the United States can learn from those mistakes.

Basically, this is actual rocket science and therefore hard to pull off, which only makes the test result that much more impressive. Still, because it’s not a perfect copy of an actual attack, any euphoria needs to be reined in just a tad.

This was an impressive test. But it’s still not the real thing.

The Pentagon released a video Wednesday showing some portions of the test. It’s definitely worth your time to watch it, if only because it’s got all sorts of cool rocket explode-y stuff.

What you just saw was the ICBM, fired from the Reagan Test Site on the Kwajalein Atoll in the Marshall Islands, heading for waters south of Alaska. Then, the defending missile was fired from Vandenberg Air Force Base in California to intercept it during its midcourse flight in space.

The test was a success, as shown in the last part of the video where you see the interceptor hit the ICBM head on. "The interceptor that we flew yesterday certainly keeps pace with and I would actually say helps us outpace the threat through 2020," Syring said.

So while Syring is happy with the outcome — and he has every right to be — there are still a few caveats worth noting about this test that was three years in the making.

First, “the test was highly scripted,” as the “target was fired right at the interceptor on a nice sunny day with lots of warning,” Jeffrey Lewis, a nonproliferation expert at the Middlebury Institute of International Studies at Monterey, noted in an interview. And that makes sense: These tests do the best they can to simulate an actual attack, but there are limitations.

After all, if an attack happens, there will likely be some warning, but probably not much. The US may not be fully confident where the missile is headed, what kind of ICBM it is (yes, there are multiple kinds), or other factors. During a test, though, those involved are mostly aware of where and when the attack will take place — taking away the elements of surprise and uncertainty.

Still, the simulators “conducted a test as close to reality as they’re physically able to given the constraints of cost” and “the realities of our testing limitations,” retired Lt. Gen. Patrick O’Reilly, a former director of the Missile Defense Agency, told me in an interview. “What they did yesterday is probably the best you can do.”

Second, as physicist Laura Grego of the Union of Concerned Scientists wrote in a recent piece, the test missile did not travel as far as a North Korean missile would need to in order to hit US territory. Per Grego, the top distance the ICBM could travel in this case was 5,800 kilometers; a North Korean missile would need to travel around 11,000 kilometers.

That matters quite a bit. One of the things testers need to know is the “closing speed” of the incoming missile — that is, how quickly the gap between the threatening missile and the interceptor closes. A test with a shorter distance changes the closing speed, and thus the conditions under which the interceptor can hit the ICBM.

Therefore, this was not a representative test of the threats facing the United States, and Lewis says “it is not accurate to describe this target as representative of a North Korean ICBM threat.”

So, while it was still impressive that the test ended with a head-on collision, the test’s scripted nature and the much-shorter distance the ICBM traveled still do not assure everyone that the US is ready to defend against a real attack.

That doesn’t mean there’s no cause for celebration. It’s still a pretty big deal that the US can even pull off a test like this. And that’s almost certainly because they’ve learned from all the previous tests — even the failed ones.

The missile testing and baseball connection

The Missile Defense Agency has come under some scrutiny for only having four of nine intercept tests finish successfully. That statistic doesn’t provide much confidence to those worried about missile threats from abroad.

But O’Reilly says that data point, and others like it, don’t actually tell you all that much.

“The problem with counting successes and failures is that it’s really a deceptive way of trying to gauge the progress of a missile program, and the reason is you don’t know what’s the difficulty level between tests,” he noted.

Let’s get to the core of what he means using a baseball analogy.

As O’Reilly helped me understand it, you have the bat and the pitcher has the ball. Sometimes, the pitcher throws a fastball; other times, he throws a curveball, or a change-up, or something else. Same pitcher, same bat, different pitch.

In other words, with each new pitch, you as the batter have to change your timing and your swing to hit the ball, and sometimes you will miss. But you will learn something new after each pitch, which in turn will help you with the next one.

Conversely, if the pitcher kept throwing the same pitch each and every time, then you will hit the ball a lot more often, but you won’t figure out if you can hit a different kind of pitch.

And it’s also worth remembering that these tests are very expensive and take a long time to set up. So even as corrections are being made between tests, it’ll take some time to know if the new calculations will work during the next test.

In sum, rocket science is hard. Really hard. So it’s worth applauding any successful outcome — especially when these tests are meant to help keep North Korean and Iranian nukes from hitting the United States.

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