美国国家公共电台 NPR Nations Rush Ahead With Hypersonic Weapons Amid Arms Race Fear（在线收听）

STEVE INSKEEP, HOST:

President Trump's national security adviser, John Bolton, is in Moscow for a second day today. He's there to discuss President Trump's pledge to withdraw from an arms control treaty that bans certain kinds of missiles. This is one sign that world powers might be returning to an arms race mentality. Now we have another sign - efforts by the United States, China and Russia to develop a new kind of missile, a weapon that can fly faster and farther than almost anything in existence. NPR's Geoff Brumfiel has the latest.

GEOFF BRUMFIEL, BYLINE: These weapons are called hypersonic weapons. And they are fast - really fast. By definition, they travel at least five times the speed of sound, thousands of miles per hour. The Air Force is currently developing hypersonic weapons, including at a place called Wind Tunnel 9, just outside of Washington, D.C.

Good morning.

DAN MARREN: Good morning. Hi, Dan Marren.

BRUMFIEL: The morning I showed up, Dan Marren, who's in charge, said the tests they were running that day were classified. I wasn't going to get inside.

MARREN: No, not at this point.

BRUMFIEL: But I was allowed in the lobby of the wind tunnel building.

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BRUMFIEL: There, Marren showed me unclassified versions of the things they work on.

MARREN: So if you look on this table here, we have several of the shapes that we've tested in the wind tunnel.

BRUMFIEL: Among the models is a sleek, silver wedge with a spine down its center.

MARREN: It's called a Waverider. And so it's a fancy way to say it rides on its own shock wave.

BRUMFIEL: Here's how the Waverider works. The wedge-shaped warhead would be put on top of a rocket and fired at enormous speeds to the very edge of space. Then it would detach from the rocket and glide to its target. Now, big countries like the U.S., China and Russia already have weapons that can do something like this. They're called intercontinental ballistic missiles, and they can hit anywhere on the planet in minutes. But those missiles just go in a straight line from launch to target.

MARREN: This vehicle would not only be able to come from space but be able to turn and bank and fly almost like a real airplane.

BRUMFIEL: And that's the real appeal of hypersonics, especially for China and Russia. They're afraid the U.S. can shoot down their ballistic missiles with missile defense. A hypersonic weapon can swerve or take a roundabout route to the target while still going incredibly fast. It's essentially unstoppable.

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BRUMFIEL: Back in August, China tested a hypersonic prototype that flew for more than five minutes and reached speeds above 4,000 miles per hour, according to state media. Russia, too, has been testing. At a missile defense roundtable last month, the Pentagon's head of research and development, Mike Griffin said he was worried the U.S. was losing its edge.

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MIKE GRIFFIN: We did the groundbreaking research. They've chosen to weaponize it. We need to respond.

BRUMFIEL: And the Pentagon is stepping up its hypersonics research. Now, there are still some big technical challenges to building these weapons. Pushing through the air at five or six times the speed of sound generates a lot of friction, and friction means heat. At hypersonic speeds, steel turns soft, like butter. In fact, the Air Force tried to build hypersonic airplanes in the 1960s, but they kept melting.

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UNIDENTIFIED NARRATOR: The thermal protection failed, permitting torch-like hypersonic air to incinerate parts of the ventral tail.

BRUMFIEL: That's an archival Air Force video showing how one experimental aircraft, the X-15, almost burned up during its flight. But James Acton, with the Carnegie Endowment for International Peace, says advanced materials and supercomputers are helping hypersonics.

JAMES ACTON: We are seeing Russia, the United States and China all conduct hypersonic tests. Many of those tests - certainly not all of them - are being successful.

BRUMFIEL: Acton also says that hypersonic weapons pose a real threat to the U.S. military. But, he says, the solution isn't necessarily to develop our own hypersonic weapons in response.

ACTON: I don't think we should develop hypersonics just because somebody else is doing it. That's an arms race. I think we should develop hypersonics if it solves specific military problems or fills specific military needs.

BRUMFIEL: For now, the U.S. is stepping up testing. And back at Wind Tunnel 9, they're ready to start.

MARREN: Game on.

BRUMFIEL: All right, game on.

As I said, I can't see anything. But Marren has come up with a solution - I can stand out back, behind the tunnel, and record the rush of air as it moves through the system at Mach 10 - 10 times the speed of sound.

(SOUNDBITE OF HYPERSONIC MISSILE)

BRUMFIEL: So is that what Mach 10 sounds like?

MARREN: That's what Mach 10 sounds like.

BRUMFIEL: It's kind of noisy.

MARREN: (Laughter) It can be, yes.

BRUMFIEL: And with the test complete, hypersonic weapons inch a little bit closer to reality.

Geoff Brumfiel, NPR News.

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