At its simplest, missile defense is the art of shooting a bullet with another bullet.

There is no part of this that is easy, and with the modern advent of hypersonic missiles, both the speeds and the trajectories at which missile interception has to take place to be successful, the already hard problem of missile defense is more daunting than ever. DARPA, the Pentagon’s home of blue-sky projects to turn hard problems into solved problems, is working on creating an interceptor of hypersonic vehicles.

The program is called “Glide Breaker.”

DARPA’s public-facing summary of the Glide Breaker program consists of a single sentence: “The Glide Breaker program began in 2018 to develop and demonstrate technologies to enable defense against hypersonic systems.”

Getting an interceptor to speed to hit a hypersonic weapon will take powerful engines, and on Feb. 10, Aerojet Rocketdyne announced that it had been selected by DARPA to develop the propulsion system for a Glide Breaker interceptor. The contractor is worth up to $19.6 million.

Aerojet has experience making both solid-fuel and air-breathing engines for hypersonic flight, and touted its prior experience with Boeing’s X-51A Waverider hypersonic demonstrator. In December 2019, Lockheed Martin named Aerojet Rocketdyne as the producer of the motor for its hypersonic missile. (This week, the Air Force canceled one of its two hypersonic missile programs.)

Before it can become a program of record, Glide Breaker has to demonstrate that the technology can achieve what is promised. Missiles on a ballistic trajectory are difficult to hit, and can release decoys or chaff to throw off possible interceptors. Success in trials is rare and difficult, and only comes under ideal conditions.

Hypersonic missiles can also maneuver in level flight, complicating the problem by multiple degrees of freedom. An interceptor will need to know not just the trajectory, but also be able to adapt to maneuvers in flight and then connect with the missile while at a safe remove from the people or places it is trying to protect.

Glide Breaker is a bet placed on the future that, with enough iteration, hypersonic interception can not only be achieved, but will be a vital part of national security for decades to come.

Kelsey Atherton blogs about military technology for C4ISRNET, Fifth Domain, Defense News, and Military Times. He previously wrote for Popular Science, and also created, solicited, and edited content for a group blog on political science fiction and international security.

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