PopularMechanics082017

NORTH KOREA:

HOW BIG A THREAT?

NUCLEAR

WARHEAD

Ready:

now or soon

Experts surmise that

North Koreans put

nuclear warheads on

short-range missiles in

2013. That technology
      can be used on an
      ICBM. “Most North
      Korean nuclear-capable-
      missiles seem to have a
      payload section about
      65 centimetres in diame-
      ter, appropriate for a
      first-generation war-
      head,” Schilling 
      says.

RE-ENTRY VEHICLE

Ready:

now or soon

One of the most challenging parts of

an ICBM flight is re-entry into Earth’s

atmosphere. It’s hard to keep a war-

head on target while it’s moving at

hypersonic speeds, when friction with

the air forms a shroud of superheated

plasma around the vehicle. “The chal-

lenge is ensuring that whatever mate-

rial burns away from the heat shield

does so in a uniform and symmetric

manner,” Schilling says. “Test footage

[from 2016] showed Kim Jong-un

examining the re-entry

vehicle that seemed to

show uniform ablation

at the conclusion of the

test.”

MAIN

ENGINES

Ready:

4 to 7 years

A March test

allowed experts

to learn about the

propellant being

used simply by

observing the

exhaust. Earlier

tests had smoky

exhaust, indicating

kerosene, but this

plume was orange,

indicating carbon,

and translucent.

“The most likely

candidate is

unsymmetrical

dimethylhydrazine,

though other

hydrazine deriva-

tives and similar

compounds are

possible,” Schilling

says. This fuel

gives a rocket

15 per cent more

power. “It was

more advanced

and efficient than

anything we had

really expected

them to be able

to develop for the

first stage of their

ICBMs.”

ROCKET

READY:

1 to 3 years

The KN-14,

which could

reach California,

has been shown

in parades but

not flight-tested.

David Wright,

missile expert

at the Union of

Concerned

Scientists, says

that the paraded

KN-14 can be

seen to have two

stages. This indi-

cates that liquid

fuel rather than

solid is being

used. Although

liquid fuel requires

relatively heavy

pumping systems,

it tends to be

better at lifting

mass. And, with

fewer stages,

there is less

potential for

complications.

Here are the mechanics of a theoretical

nuclear ICBM attack.

BY JOE PAPPALARDO

NORTH KOREAN DICTATOR Kim Jong-un can
launch a short-range missile with a nuclear
warhead, but the United States remains at a
relatively safe distance. For now. North
Korea enjoyed several milestones on the way
to a nuclear intercontinental ballistic missile
in 2016, including a warhead test and the
successful launch of a satellite. According to
John Schilling, an aerospace engineer and con-
sultant to the North Korea-monitoring web-
site 38 North, Kim could achieve “initial
operational capability in late 2021”. Which,
when you’re dealing with a maniac, is much
closer than its enemies would like it to be.

ILLUSTRATION BY TAVIS COBURN

HOW YOUR WORLD WORKS

12 http://www.popularmechanics.co.za _ AUGUST 2017