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Ask a Scientist: Calling Out the Hype Over Hypersonic Weapons

, senior writer | April 2, 2021, 10:00 am EDT
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This post is a part of a series on Ask a Scientist

China, Russia and the United States are now all rushing to develop a new type of missile that is purportedly faster, more accurate, more maneuverable, and stealthier than long-range intercontinental ballistic missiles (ICBMs). Called “hypersonic” missiles because they can reach velocities greater than five times the speed of sound—known as Mach 5—they are at least six times faster than commercial airliners.

Russia has already deployed at least one hypersonic missile, which is capable of carrying a nuclear warhead. This has prompted quite a bit of handwringing in US military circles, and the Pentagon plans to spend billions of dollars on large-scale production of hypersonic weapons in the coming years.

The Union of Concerned Scientists has been closely watching these developments. In 2015, Dr. David Wright—Global Security Program co-director until 2020—contributed an appendix to a hypersonic weapons study published in the peer-reviewed international journal Science & Global Security. By 2018, it became apparent that a looming arms race over hypersonic missiles could pose a significant threat to international security. So Wright and his team decided to bring in an outside scientist through the UCS Kendall Science Fellowship program to investigate further.

The program selected Dr. Cameron Tracy, who—before coming on board for the two-year fellowship in September 2019—had been doing research at Harvard’s Belfer Center for Science and International Affairs and Stanford’s Center for International Security and Cooperation after earning his PhD in materials science and engineering at the University of Michigan. Given that his work at Harvard and Stanford focused on nuclear arms control and the interface between science and security policy, he was a perfect fit for the task.

Thus far, Tracy has posted five essays on various aspects of hypersonic weapons, taped a half-hour podcast, and coauthored a technical study, Modelling the Performance of Hypersonic Boost-Glide Missiles, with Wright in the January issue of Science & Global Security. His latest study, Slowing the Hypersonic Arms Race: A Rational Approach to US Hypersonic Missile Development, will be released later this month.

I recently asked Tracy a few questions about the hype over hypersonics. The transcript of our exchange is below.

EN:  Let’s start with the basics. What are hypersonic missiles? Are they nuclear weapons? What are their proponents claiming they can do?

Cameron Tracy is the Kendall Fellow for the Global Security program at the Union of Concerned Scientists. His work focuses on nuclear arms control and the interface between science and security policy.

CT: Hypersonic weapons are low-altitude, high-speed missiles that can carry either conventional or nuclear warheads. They might be designed to fly around 600 miles, for use in a specific theater of operations, or many thousands of miles, for intercontinental strikes.

As you mentioned in your introduction, proponents claim they are faster, stealthier, and harder to intercept than ballistic missiles—the current state-of-the-art in rapid warhead delivery.

For instance, in 2019 the commander of the US Strategic Command testified before Congress that a hypersonic missile could strike the continental United States in half the time it would take an ICBM launched from Russia, which is about 30 minutes. And last year, the under secretary of defense for research and engineering said hypersonic missiles are “20 times dimmer, or more, than the targets [the United States is] able to track,” and that new sensors would be needed just to see them.

Those are just a couple of examples. The military trade press—and the mainstream press—repeat these claims as fact. A recent story stated unequivocally that radar cannot pick up Russia’s hypersonic missiles, while The New York Times ran a column in January 2020 arguing that hypersonic missiles are a “game-changing” new weapon—“unstoppable,” “phenomenally accurate,” and able to “reach nearly every coordinate on the surface of the earth within 30 minutes.”

EN: I read that Times column. It was pretty scary, actually. Especially that line: “Death from the air, guaranteed on-time delivery.”

When you began your investigation, you assumed that some of the claims about hypersonic missiles might indeed be a bit, ahem, hyperbolic, but you thought that they would generally be borne out by your technical analysis. That didn’t happen.

CT: That’s right, I originally planned to analyze the extent to which hypersonic missiles could undermine international security, assuming at the time that these weapons were indeed uniquely fast and evasive. But as the team at UCS started running our calculations, we quickly found that the claims were not supported by the science.

Are they faster than existing ballistic missiles? No.

To be sure, hypersonic weapons are fast. But this is nothing new. Even the first modern missile, the German V-2, achieved near-hypersonic speeds in the 1940s. ICBMs, which the United States and Russia have fielded since 1959, travel much faster—more than 20 times the speed of sound.

So how could that defense official claim that hypersonic weapons would halve the time necessary for an attack on the United States, if ballistic missiles fly just as fast? Simple—by comparing a ballistic missile launched from Russia with a hypersonic weapon launched much closer to the United States. When launched from the same distance, a ballistic missile could reach its target as fast or faster than a hypersonic missile. It was an apples and oranges comparison that misrepresents the facts.

Are they stealthier than ICBMs? No. Are they undetectable? No.

The fastest hypersonic weapons are launched on the same rocket boosters that launch ballistic missiles. The rockets’ hot exhaust makes it easy for satellite-mounted infrared light sensors to follow both weapons. But hypersonic missiles are unique in that the air resistance they encounter in their low-altitude flight keeps them extremely hot—and visible to these sensors—even after their rocket boosters run out of fuel.

Our calculations show that hypersonic missiles would remain visible to currently deployed satellites for much of their flight. Only if they slowed to the nearly the lower limit of hypersonic speeds—around Mach 5—would detection become an issue. But that, of course, would defeat the main purpose of a high-speed missile. On top of that, ground-based radar systems would be able to detect hypersonic weapons once they flew close enough that air defenses could intercept them.

Once again, top government officials—as well as think tank analysts and journalists—overstate the facts.

EN: That brings up a key point you make in the January paper you coauthored with David Wright. There appears to be a kind of “group think” going on here. As you explain, social scientists call this phenomenon “heterogeneous engineering.”

We saw the same thing happen over the last two decades when it comes to the US antiballistic missile defense system. The generals say it works, the defense contractors say it works, the news media say it works, and Congress spends billions of dollars on it. The problem is, as David Wright and UCS scientists Lisbeth Gronlund and Laura Grego have been pointing out for the last 20 years, the system has never been demonstrated to work in a real-word situation and can easily be foiled.

CT: There can be many reasons for the Pentagon to develop a particular weapon system. Some might relate to its performance and a need for certain new capabilities. But organizational studies of past US missile development have consistently found many other motivations at play, which often have nothing to do with performance. For example, weapon development can be a major source of funding, of technological prestige, or a key aspect of the fierce competition among the military branches.

So we end up with situations where defense officials, contractors, and others who stand to gain from research and development dollars might want a particular weapon—or a related technology, such as missile defenses—regardless of what it actually does. But they cannot build a missile alone. They need the support of other key players who may have different motivations—congressional appropriators holding the government’s purse strings, for example. To convince members of Congress that a new weapon is necessary, proponents try to cast it as a revolutionary technological advancement. Since the engineers and analysts at the Pentagon and corporations designing these weapons are considered the experts on the technology, they are uniquely able to shape perceptions of weapon performance, regardless of whether their incentives have anything to do with performance.

This is where the term “heterogeneous engineering” comes in: engineering not just the missile itself—metal, wires, and circuit boards—but also social perceptions about what that missile does and why it is supposedly necessary. That directly leads to these misleading statements about hypersonic weapon speed, stealth, and other performance characteristics.

The technical facts, of course, tell a very different story. That’s why independent technical assessment, like what UCS does, is so important to ensuring rational, effective US defense spending.

EN: As you mentioned before, your original task when you joined UCS as a Kendall fellow—before you discovered that the hype over hypersonics had little basis in fact—was to examine the implications of this new weapon for international security. The Biden administration thankfully extended the New Strategic Arms Reduction Treaty (New START) treaty with Russia, the only remaining agreement limiting the two countries’ nuclear weapons, but the treaty does not cover hypersonic missiles. Given hypersonics are apparently not as potent as advertised, what needs to happen when China, Russia, and the United States are going full-tilt to develop them?

CT: For now, the best thing the United States can do is to ensure that it develops these weapons only if their benefits outweigh the costs. Those costs for hypersonic missiles are massive. This year’s defense budget dedicates $3.2 billion to hypersonic systems, a sum that has been increasing year after year. A recent Government Accountability Office report found that these programs are plagued by recurring cost overruns and delays.

There are also costs in terms of US security. An arms race, even over an ineffective weapon, increases international tensions and could make conflict among China, Russia, and the United States more likely.

Fortunately, these risks can be addressed. The hypersonic arms race is, in part, a response to the US rush to develop these weapons as well as missile defenses. This makes restraint an attractive option for slowing the arms race. If the United States were to reduce its investment in hypersonic weapons to a level proportionate to their actual strategic utility, it would reduce the impetus for China, Russia, and other countries to try to counter that development with their own weapons. Getting a grip on hypersonic missiles may even be done cooperatively. Some thoughtful defense analysts, for example, have proposed multilateral limitations on the testing and proliferation of hypersonic weapons.

Still, progress on such risk mitigation measures can proceed only if the United States grounds its approach to these weapons on a rational, technical assessment of their true capabilities, not on hype. To do so, Congress needs access to clear, unbiased information on hypersonic weapon performance, and the Biden administration needs to make the provision of this information a priority.


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  • Robert Berend

    Re: “… last year, the under secretary of defense for research and engineering said hypersonic missiles are “20 times dimmer, or more, than the targets [the United States is] able to track,” I hope someone informs that undersecretary that “20 times dimmer” is mathematical illiteracy. One-twentieth would be correct. Twenty TIMES something is always a larger number!! You do not earn two times less than your boss–you earn half, or she earns two times more.