How to Launch an Intercontinental Ballistic Missile

North Korea likes putting on a big show of testing its missiles. The small country has conducted tests with increasing frequency, and recently rolled out the advanced Hwasong-14, which some analysts think think could could soon carry a small payload halfway around the world — far enough to reach New York City or Washington D.C.

It’s frightening to think that US cities could be within shooting range of North Korean nuclear-tipped rockets. But most foreign policy experts see the DPRK’s nuclear buildup as a method to gain negotiating power over the United States, not the run-up to a catastrophe.

Still, it’s worth understanding how the Hwasong-14 works.

What defines an ICBM?

An intercontinental ballistic missile isn’t really one thing. You can build a rocket however you want, and as long as it can cross an ocean to strike your enemies on the other side, it’ll earn an ICBM designation.

The HS-14, as best as anyone can tell from photos, is a two-stage rocket. It’s got a large lower stage to do some initial heavy thrustin and a smaller top stage to accelerate it further toward its target.

Why North Korea Missile Tests Always Go Into Space

If you’re a North Korean rocket scientist getting ready to launch a missile, you’ve got a few questions to answer. The first, and most important: Where do you want the missile to go?

Keep in mind, the whole region surrounding North Korea is bristling with detectors and military weaponry trained at the isolated state. Japan, South Korea, and their powerful ally the United States are ready to respond with overwhelming force to a North Korean attack at a moment’s notice.

So you don’t want to do anything that even might look like an attack, and find yourself responsible for a swarm of nuclear-tipped LGM-30 Minuteman missiles screaming through the outer atmosphere in the direction of your base.

That rules out overflying Japan to the east, or South Korea to the south. To the west and north, you’ve got China and Russia — who probably wouldn’t be too thrilled about an HS-14 crashing down in their territory either.

In other words, you’re left with one remaining direction to go: Straight up in the air, into space.

How North Korea Tests Its ICBMs

North Korea rolled a very big truck into the middle of a spot of bare land in Chagang Province on Friday, in the north of the country. Heavy lifters at the back of the truck pushed, and the large missile on its back tilted straight up into the air. This missile was refined and souped-up, prepared for a much more dramatic display than its first July 4th test — a test that already shocked analysts, and travelled more than seven times higher than the International Space Station.

At 11:41 p.m. local time, or Friday morning on the East Coast of America — an unusual nighttime launch — the missile test began.

Liquid fuel stored in the rocket’s midsection coursed downward. Most of it ignited and exited under pressure through a single engine at the bottom of the vehicle. The tremendous force of the hot fuel ejecting pushed the rocket upward, accelerating it toward its top speed.

A small portion of that fuel diverted, igniting and shooting out through four smaller angled thrusters. Those thrusters kept the rocket stable, and allowed for course corrections. Within seconds, the whole contraption was forcing itself through the atmosphere far above its launch site.

For a brief while, probably no more a minute or two based on similar equipment, the rocket motored its bulk upward. At some point, the first stage ran out of fuel and detached, and the second stage ignited, taking advantage of the reduced weight to loft the warhead even higher.

Then that stage died as well, and still the rocket shot upward. It passed the orbit of the ISS and our planet’s other low satellites, then doubled it, then tripled it — eventually topping out at 2,300 miles.

Along the way it drifted a bit, out over the ocean and toward Japan. And on the way down, it kept drifting, likely guided by what appear to be eight retrorockets in its nose cone.

Down it fell, accelerating faster and faster. A shroud covering its payload fell away. Analysts don’t know for sure what it revealed. Their best guess though is what’s a “blunt body re-entry vehicle” — a payload carrier with a big flat surface pointing downward, like a smaller version of the cones NASA used on the Apollo missions to carry people.

When that blunt surface struck the atmosphere, it generated immense energy and heat, but the shape created a shock wave that travelled in front of the rapidly descending payload, distributing heat away from its surface. If a nuclear bomb were inside, that bow shock would have protected it from burning up before it could detonate.

Soon after re-entering the atmosphere, the payload splashed down into the water 621 miles from its launch site — and well within Japanese-controlled waters. It was 47 minutes after the rocket’s ignition.

The Rest of the World Determines What Happened

North Korea doesn’t put out key statistics that would let international observers precisely calculate the potential of its rockets. So analysts have to rely on pictures put out through state propaganda and observations from afar.

That propaganda is designed to provoke a response from the rest of the world, and it’s already succeeded.

Without knowing the exact size and weight of the missile or its payload, there’s room for quibbling about its range. Most folks have agreed since the July 4th test that if the HS-14 were aimed at an easterly angle and took advantage of the Earth’s rotation, it could likely hit Alaska or Hawaii.

This test went a lot higher.

More conservative analysts like John Schilling over at 38 North said then that that’s about the limit of the rocket’s demonstrated potential, but that with some tweaking it might be able to carry a 500-kilogram payload to San Diego.

Jeffery Lewis of the Middlebury Institute of International Studies was a bit more alarmist, arguing that the missile could likely strike New York or D.C. He took to Twitter to say Friday’s more dramatic test confirms his suspicions.

The United States does have some missile defenses, which might be able to shoot an ICBM out of the sky about half the time. So the next steps in North Korea’s ICBM program may be less rocket power than figuring out ways to fool those defenses.

That North Korean engineer’s about to end up in a race with Americans to weight that coin flip in their favor.