Hypersonic weapons have been advertised as the next best thing in defense technology. But is this true? They are fraught with a number of technical and social challenges, and many scientists believe hypersonic missiles don’t live up to their press.
Technical Challenges and Risks
It may go without saying, but traveling at hypersonic speeds isn’t easy. At Mach 5 and above, objects moving through air actually start to loosen the bonds between molecules of oxygen and nitrogen. Some of these free-flowing atoms can damage the surface of the vehicle.
Then there’s the heat. Moving this fast causes objects to heat up to around 3,000 degrees Fahrenheit. Finding materials that don’t melt at these temperatures is difficult. Since hypersonic vehicles don’t leave the earth’s atmosphere like space shuttles or ballistic missiles, they stay hot longer. The Defense Advanced Research Projects Agency (DARPA) and the Air Force have done extensive research on the best materials to use for a vehicle’s leading edges, seals, and insulation.
Next is the issue of drag. The faster a vehicle goes, the more drag it experiences. Swimmers experience this problem when trying to shave seconds off their race times. While most of us don’t think of air as a fluid, in fluid mechanics (a branch of physics), it’s viewed the same way. An object moving through air encounters resistance just like a swimmer moving through water.
Drag causes anything moving at hypersonic speeds to lose energy exponentially. According to this article in Scientific American, “A glider flying at Mach 5 will lose energy 125 times faster than at Mach 1; one flying at Mach 20 will lose energy 8,000 times faster.”
As a result, it turns out that hypersonic glide vehicles aren’t actually faster than ballistic missiles flying at a lower (depressed) trajectory over the same distance.
With their high speeds, hypersonic weapons also have a more difficult time maneuvering. If a hypersonic glide vehicle changes course even 30 degrees during a flight, its loss of energy will reduce its range.
Another issue is visibility. Many claim that hypersonic weapons can’t be detected by current defense systems. However, scientists say the heat hypersonic weapons produce would cause them to glow, making them visible to systems the United States of America already has in place.
While there are certainly people who say hypersonic weapons are a necessary part of modern warfare, scientists who understand the physics say the emphasis on these weapons is unfounded. They question whether this technology is worth the money spent on it, and the escalating arms race it’s causing.
Hypersonic Weapons and Global Security
A hypersonic arms race is underway. Russia and China both have some form of working hypersonic missiles in their arsenals. As a result, the U.S. has increased spending on hypersonic research and gone into partnership with Australia and the United Kingdom to bolster hypersonic weapon development. North Korea and India have also claimed successful hypersonic missile tests. South Korea is developing a hypersonic cruise missile.
This is concerning since an arms race can escalate tensions between countries. How long will it be until a country’s military wants to try its state-of-the-art technology? Russia has already used some of its hypersonic missiles against the Ukraine.
Others worry that a hypersonic missile attack could provoke a nuclear war. Since it’s impossible to tell if a hypersonic weapon holds a nuclear warhead or another type of explosive, a target country might retaliate with a nuke in the heat of the moment.
Yet some scientists, analysts and the U.S. Secretary of Defense Lloyd Austin don’t see hypersonic weapons as a threat. Both Russia and China already have ballistic missiles that could strike the U.S. after all, and they haven’t been used.
Even with these voices of dissent, it isn’t likely the U.S. will step back on hypersonic weapons research. The Pentagon requested $4.7 billion for hypersonic research in the 2023 fiscal year and the Missile Defense Agency asked for $225.5 million. President Biden gave his support for hypersonic research in a March memo.
Ethics and Hypersonic Tech
The ethics of hypersonic technology are complicated.
The U.S. is not designing most of its hypersonic weapons to carry nuclear warheads, instead preferring to develop non-nuclear missiles capable of precision strikes.
Still, there are those who would question whether spending billions of dollars is justified while 17% of American children are living in poverty.
There are also the victims of future missile attacks to consider. It is estimated that between 22,000 and 48,000 civilians have been killed due to U.S. drone and air strikes since 2001. How many more will die with hypersonic technology on the scene? Since Russia has already used them on civilian targets, that tally may already be underway.
And as Dr. Aditi Verma, a postdoctoral fellow at the Belfer Center's Project on Managing the Atom and the International Security Program, pointed out, weapons must also be tested somewhere. What is the impact on the people who live near testing sites and on the environment?
Although there has been a compelling case made for the necessity of hypersonic weapons, it is not without its critics.
There is good science showing hypersonic missiles can’t really live up to their claims. Still, research into hypersonic missiles is likely to continue for the foreseeable future.
But hypersonic technology isn’t only for missiles. Check out RSnake’s chat with rocket scientist Dr. Leon Vanstone to find out how hypersonic technology could be involved in hypersonic flight and space elevators.