Sunday, June 13

Hypersonic Superweapons Are a Mirage, New Analysis Says


Military experts call hypersonic warheads the next big thing in intercontinental warfare. They see the emerging arms, which can deliver nuclear or conventional munitions, as zipping along at up to five miles a second while zigzagging through the atmosphere to outwit early-warning satellites and some interceptors. The superfast weapons, experts say, lend themselves to surprise attacks.

President Trump has bragged about his “super-dupers,” even referring to the planned weapon as “hydrosonic,” a brand of electric toothbrush. Last year, his budget asked the Pentagon to spend $3.2 billion on hypersonic arms research, up $600 million from the previous year’s request. And as President-elect Joseph R. Biden Jr. takes command of the nation’s military, he will have to consider whether to sustain the defense work undertaken in the Trump years.

Now, independent experts have studied the technical performance of the planned weapon and concluded that its advertised features are more illusory than real. Their analysis is to be published this week in Science & Global Security.

In an interview, David Wright, a physicist at the Massachusetts Institute of Technology and an author of the new analysis, called the superweapon a mirage.

“There’re lots of claims and not many numbers,” he said. “If you put in the numbers, you find that the claims are nonsense.”

Military officials called the paper insubstantial, saying it was based on outdated data. But they declined to disclose new findings.

“Due to the classified nature of hypersonics technologies, we are not at liberty to publicly discuss current capabilities,” Jared Adams, chief spokesman for the Defense Advanced Research Projects Agency, or Darpa, said in an email.

Richard L. Garwin, a physicist and longtime adviser to the federal government, called the paper “very good and important.” He added that he had provided his own similar criticisms of hypersonic warheads to defense officials.

James M. Acton, a nuclear analyst at the Carnegie Endowment for International Peace, called the paper “a serious, credible and important piece of work.”

The computer simulations drew on the physics of moving bodies and public disclosures about the Hypersonic Technology Vehicle 2 in order to model its most plausible flight paths. The team zeroed in on signature phases of hypersonic flight — when the vehicle zooms through the atmosphere and then plunges to hit a target.

The two experts say their computer modeling fills in public gaps on the weapon’s overall performance as well as its potential interactions with existing military systems for detecting and defeating weapons launched from distant sites.

In their paper, they see the weapon as essentially failing to outwit early-warning satellites and interceptors. For instance, current generations of space-based sensors, they report, will be able to track the weapon’s fiery twists and turns during most of its flight through the atmosphere.

It’s what aeronautical engineers call the lift-to-drag ratio. The esoteric term is a measure of lifting power versus drag. Lift pushes a speeding aerodynamic body up and atmospheric drag tries to counteract the forward motion, at worst prompting a stall.

Dr. Wright said the team’s analysis of the hypersonic vehicle used a lift-to-drag ratio of 2.6. In contrast, jetliners and some birds have a ratio approximately eight times higher. In other words, the warheads at best are unimpressive fliers.

The limited power of the curved, blistering hot surfaces to generate a substantial lifting force without also producing lots of drag undermined claims that the weapon can fly long distances on complex trajectories, he said.

“Unless they’ve found some magical way to keep these systems up,” Dr. Wright said, “they’re going to have problems.”

Policy experts expect the Biden administration to focus on fostering arms control, and it seems likely that the Trump administration’s plans for hypersonic warheads will get close scrutiny. Hypersonic arms are among the topics that defense experts see administration officials as addressing in early talks with Russia and China, including the possibility of finding ways to impose restraints.

Ned Price, a spokesman for the Biden transition team, declined to comment on the issue of hypersonic warheads.

“President-elect Joe Biden will have an experienced team to sort through these complicated issues,” Hans Binnendijk, a former National Security Council official, wrote last month in suggesting ways to reinvigorate arms control. “But it will take time and creativity to be successful.”





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