INTERVIEW: Hits and Missiles

By Reuvain Borchardt

Iain Boyd discusses America’s missile defense, following a campaign promise by Donald Trump to “build an Iron Dome over our country.”

Boyd is the Director of the Center for National Security Initiatives and the H.T. Sears Memorial Professor of Aerospace Engineering Sciences at the University of Colorado Boulder. 

He was awarded the Chief of Staff of the Air Force Award for Exceptional Public Service for his leadership role in the Air Force Scientific Advisory Board (AFSAB).

Boyd received a Ph.D. in aeronautics and astronautics (1988) from the University of Southampton in England. He worked for four years at NASA Ames Research Center in the areas of aerothermodynamics and space propulsion. He was a faculty member in mechanical and aerospace engineering at Cornell University for six years, and a professor of aerospace engineering at the University of Michigan for 20 years. His research interests involve the development and application of physical models and computational methods for analysis of nonequilibrium gas and plasma dynamics processes in aerospace systems. He has authored over 200 journal articles, more than 300 conference papers, and a book titled “Nonequilibrium Gas Dynamics and Molecular Simulation.” 

He is a fellow of the American Institute for Aeronautics & Astronautics, the American Physical Society, and the Royal Aeronautical Society.

Donald Trump recently said at a rally, “I will build an Iron Dome over our country, a state-of-the-art missile defense shield.”

First of all, how does the Israeli Iron Dome system work?

It has several elements to it. It starts with radars that detect potential threats coming into the area that a particular system is defending. It tracks whatever this object is and makes a quick determination as to whether it’s an actual threat and not some other benign object like an airplane or a flock of birds. It then communicates that information to a control center that decides, if you’ve got multiple Iron Dome installations, which one is going to address this particular threat coming in. And so that decision is made, and then interceptor missiles are fired at the threat. And again, a determination is made, whether the threat has been neutralized or not, and they could fire further objects at the threat. So there are several key elements in the Iron Dome System, and carefully coordinated decisions being made very quickly. 

Iron Dome is designed to protect against very-short-range rockets, up to 70 kilometers (around 43 miles). It’s not really protecting against long-range, ballistic missiles, for example.

How exactly does it shoot down the rockets?

For the short-range rockets that Iron Dome defends against, it fires a rocket, but that doesn’t actually directly run into the enemy rocket; it’s not what we call a kinetic kill. Rather, it gets close to the threat and then it explodes, and basically just knocks the other rocket off its course. It may destroy it, but it doesn’t need to; it just needs to confuse it, knock it off its original path.

Iron Dome typically protects against rockets fired by Hamas in Gaza or by Hezbollah in Lebanon. But if a country farther away, like Iran, were to shoot a missile at Israel, would Iron Dome not detect and shoot it down?

It wouldn’t detect the launch. But it would detect the missile once it gets into that 70-kilometer range within which Iron Dome operates; it would be detected and addressed with some probability of success by Iron Dome. And the probability is important. Even though Iron Dome is described as the most capable air defense system in the world, of course nothing is 100% effective. But the short answer to your question is, yes, Iron Dome could neutralize something shot off from Iran. 

If America were attacked, it would probably come from a much farther distance than the threat Israel faces from Hamas and Hezbollah. It would probably be from a place like North Korea, China, or Iran, thousands of miles way. 

Does an Iron Dome system like what Trump talked about, over America, make sense?

It would seem that that’s not what is needed right now. Unless, again, we had something like the Cuban Missile Crisis of 1962 — if somehow, there was a bunch of rockets and missiles close to the American homeland, in a neighboring country or on ships. 

But, as you said, today the missile threats the U.S. homeland faces are long range. And Iron Dome itself would not be a good system to protect against those kinds of threats. The U.S. has extensive capabilities and plans for defense against larger, long-range ballistic and other missiles, already in place. Billions and billions of dollars are being spent on upgrading the American defense system against long-range ballistic missiles.

If someone shoots a missile at the U.S., what system do we have in place now to alert the U.S. government, and then for the government to alert the citizens?

The homeland defense is called Ground-Based Midcourse Defense, or GMD. It’s comprised of a number of large interceptor missiles in silos across the country. During the Cold War, they  were arranged to defend against Soviet threats coming over the North Pole, over Canada and into the U.S. There are some now in the West Coast to defend probably mostly against North Korea, maybe China too. They intercept these ballistic missiles in space, and try to blow them up in space, so that, particularly if they’re nuclear, there aren’t any collateral effects below where the intercept occurs.

We often hear about ballistic missiles and cruise missiles. What are the differences between the two? 

A ballistic missile is kind of like a cannon ball. It gets accelerated by a rocket, and then it just falls under gravity. So it goes out of the Earth’s atmosphere off into space in a big arc. And then it turns over, and comes back down again, still in space and then back into the Earth’s atmosphere. That’s how it can travel thousands of kilometers. It’s pretty sophisticated, but they’re relatively easy to track because of this cannonball-like arc motion. Once you’ve detected it and have a track on it, it’s fairly easy, almost like high school math, to be able to figure out its trajectory.

A cruise missile is very different. A cruise missile will have a propulsion system — an engine of some kind that is powering it all the way through its flight. When we fly on airplanes, pilots sometimes say, “We’re now cruising at such-and-such altitude.” Cruising just means you’re going on a flat and steady flight path or trajectory. And you’re able to do that because you’ve got the engine on the airplane overcoming the “drag” — the force that tries to slow you down. The cruise missile has an engine that’s burning all the time, it’s not going on a big arc; it’s in level flight, and can operate close to the ground. Because they’re below the radar, they’re difficult to see. And they can also sometimes maneuver from side to side and up and down, which makes them even more difficult to track and destroy. 

But cruise missiles cannot go as far as ballistic missiles, because you would need too much fuel to make that work. So they’re very different in terms of engineering and design. And they present a different kind of challenge and threat to defend against.

So the big question is: Do you believe America’s current system is sufficient to protect it against an attack from, say, North Korea, or some other enemy we’re not thinking about yet? 

I think we have a good system in place. 

We saw in the Hamas attacks on Israel that a defensive system can always be overwhelmed by numbers. The Cold War was strange in many ways, but looking back on it, our system worked: The U.S. had a large number of missiles, and so did the Soviet Union. And it was basically a standoff. What if the Soviets launched an all-out attack that would overwhelm the U.S. defenses? The U.S. response would be to launch an all-out counterattack on the Soviet Union, whose defenses also would be overwhelmed. I think numbers can always overwhelm any of these defensive systems. We saw that with Hamas, and it was the underpinning of deterrence in the Cold War.

So, if you have a nation that has less to lose, or erratic leadership that is willing to play the game of just sending a large number of missiles against the U.S., it might overwhelm our defensive system. So, one-on-one, I think the system is pretty good. But if somebody fires enough threats against it, it might be challenged. 

If North Korea or Iran or whoever were to fire a missile today at the U.S., whether nuclear or conventional, how much warning would America have, and how would it alert its citizens in the area in which it’s expected to land?

On the order of 30 minutes from North Korea or Russia. Longer from Iran.

And the alert systems would be like those beeps we get on our cellphones when there’s an Amber alert or a flood warning? 

Yes, it would be something like that. It would go out on people’s phones, on TVs, maybe email, every communication form there is. And again, if it was just one or two missiles, I’d be fairly confident that they would be shot down.

So, we started off by talking about Trump’s comment about making an “Iron Dome” across America. Do you believe that if he were elected, there would actually be some major policy change in rocket defense?

Or is it just a bunch of campaign talk?I think it’s unlikely there will be any major changes as a huge amount of money has already been invested in the current capabilities. It is clear that these old Cold War systems do need to be upgraded and replaced. Also, I’m sure countries around the world are looking at what has happened in the Ukraine and in the Middle East, and it’s helping to inform their missile-defense approach and strategy. So I think there’s something to be said for asking, “Is the Cold War approach still what is needed?” I think the answer is yes, in part, and maybe other things are needed, too. You cannot sit on your laurels and think, we’ve got good protection today, so we never need to worry about it. It definitely needs to continually be evaluated. And if that’s what Mr. Trump was saying, I think that’s true. It could also be, like you said, a little bit of politics. 

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rborchardt@hamodia.com