Speed, maneuverability of hypersonic missiles create challenges for missile defense

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February 16, 2023

Tracking hypersonic missiles today isn’t like missile tracking in the old days. Missiles could be tracked by radar, troops could be warned, and hopefully disaster and death averted. The situation is very different today.

“Missile vehicles have gotten so fast that they are inside the target-tracking loop,” says David Murray, senior applications engineer at Times Microwave Systems (Wallingford, Connecticut). “By the time [the radar] sees it, it’s not there anymore. By the time you get a weapons lock on it, it’s gone. So the game changes completely.”

John W. Otto, senior director of advanced hypersonic weapons at Raytheon Missiles & Defense (Tucson, Arizona), says that tracking hypersonics is “exponentially” more challenging in today’s environment.

“Hypersonic missile systems alter warfighting on a strategic and tactical level and can deliver payloads farther and faster than ever before,” Otto says. “They move nimbly enough to avoid detection and dodge defensive countermeasures.”

Detecting, tracking, engaging hypersonic missiles

An end-to-end missile-defense system must effectively detect, track, and engage a missile moving at hypersonic speeds; the industry continues to work out the right solution to dealing with hypersonics. Murray believes this could take many forms: It could be networks of radars, or it could be satellites using networks of radars, for example. Moreover, the satellites might rely more on optical sensors than radar – after all, a missile moving at Mach 5 gives off an extensive heat signature, so using optics rather than radar may be a more effective way to track it. There are a variety of options, and the industry is examining many of them.

“All of this technology will be meshed in a network for the good guys to find the bad guys’ weapons,” Murray says. “What has to improve is closing that targeting loop down, which means faster processing and frequencies of higher resolutions. All of those are natural evolutions of radar technology.”

There are multiple ways to engage hypersonic weapons. Of course, the best option is to shoot it down on the launch pad – but once it leaves that launch pad, you have to be prepared to engage it. One option is the traditional bullet-on-bullet approach, while another is to blast the area with a “shotgun shell”-type weapon that would put up a screen the missile would have trouble getting past without colliding with the shrapnel, Murray says.

Multiple efforts are underway to find an interceptor that can more effectively destroy a hypersonic missile. Otto says that Raytheon is developing an interceptor focused on hypersonic missile defense, noting that while today’s interceptors like the SM-6 can defend against hypersonic missiles in the terminal phase and the SM-3 defends in the ballistic phase, they are not optimized to defend against hypersonic glide vehicles in the long glide phase after launch. Raytheon’s Glide Phase Interceptor (GPI) aims to fill this gap and would fit into the Aegis Ballistic Missile Defense system, he says.

Lockheed Martin is also developing an interceptor for hypersonic threats known as the Next Generation Interceptor (NGI). It is designed for the Missile Defense Agency’s Ground-based Midcourse Defense system. (Figure 1.)

[Figure 1 | The NGI is a missile-defense interceptor program designed to protect and defend the U.S. from intercontinental ballistic missiles. This program will serve as a first line of a layered missile defense architecture against evolving threats from rogue nations.]

Seeking a holistic solution

The best way to tackle a challenge like this is by taking a holistic approach to solve it, Murray says. That means assembling experts on platforms, radars, missiles, and other tech to determine what technologies can help solve this challenge, whether advancements in high-temperature materials, direct-launch devices, or even coaxial-cable assemblies.

The reality is that today’s conventional technology is not very effective in finding and tracking hypersonic weapons, so the U.S. military needs to come up with new solutions, Murray says.

“It’s a weapon with a different signature than a conventional weapon, so you would optimize your search technique based on the signature it’s giving off,” he says. “So you’ll still get a good radar cross-section return on it – actually larger because of the very nature of the plasma [surrounding the vehicle] – but you’ve got to be looking in the right direction at the right time. That’s the problem.”

The secret to defeating any missile threat, whether hypersonic or conventional, is to locate it as soon as possible. One possible way to make it easier to do that is to expand the range of the radar that is looking for those weapons. That carries its own set of challenges, Murray says.

“For radar to see farther, it has to be a higher or lower frequency or a higher power,” he says.

However, those improvements typically come at the expense of something else. “Higher power involves more expensive parts with lower reliability,” he says.

Increasing maneuverability: a challenge

The military uses so-called staring technology in the form of satellites that are able to keep an eye out for hypersonic launches. This reality prompts the question: How quickly can the military react to that launch and get the information to someone in the track of the missile?

“That’s a major problem with hypersonic missiles,” Murray says.

And it’s not just their speed that is a problem, but also a growing unpredictability in the track of the missiles. “An ICBM [intercontinental ballistic missile] is hypersonic, but it’s a pretty predictable arc,” Murray says. “When you know the target based on the trajectory, you can identify the target location. [Hypersonics] get around that by putting something in orbit and releasing it from orbit when they want. Then you have cruise missile paths, glide vehicle paths, and they’re maneuverable. So it’s very hard to predict where something is going to hit.”

Raytheon’s Otto agrees: “Unlike the traditional BMD [ballistic missile defense] system, which was built for ballistic missile threats with a clear and predictable trajectory, like throwing [a] football, the future architecture needs to evolve to account for proliferation of unpredictable, survivable threats which can quickly change course and can occur simultaneously to evade our sensors,” Otto says. “A key strategy will be getting eyes on the threat through networked sensors from space to ground to create a better threat picture.”

Radar developments are key

Better radar technology may be able to help with spotting these maneuverable and unpredictable threats, Murray says. Developments in synthetic aperture radar/inverse synthetic aperture radar (SAR/ISAR) and processing speeds will be critical to that effort, Murray says. “So it isn’t the array itself, but maybe [the technology] behind the array,” he says.

Murray says that Times Microwave Systems is doing a lot of work at the component level and pursuing technology in all areas to find a breakthrough.

“It’s across the board: A better radome, the apertures themselves if they are not optimized for that, and whatever signal comes off of a radar needs to get to whatever processes it with maximum clarity and minimum loss,” he says.

For its part, Raytheon is focusing on improving digital technologies and computing power when it comes to radar, Otto says.

“The development and engineering environment has changed greatly and will continue to get faster with new digital tools and engineering approaches,” he says. “To defend against hypersonics, we need to track the threat through their entire flight from launch to defeat. Distributed sensing is critical; networked sensors from space to ground using advanced command and control to detect and track the target create a better threat picture and enable timely decisions.”

Currently, Raytheon is building a radar for the U.S. Army known as the Lower Tier Air and Missile Defense Sensor (LTAMDS). (Figure 2.) It is a 360-degree Active Electronically Scanned Array (AESA) radar that is designed to track both ballistic and cruise missiles, along with drones and aircraft, Otto says. The company aims to increase radar signal, enhance sensitivity for longer range, and increase resolution, capacity, and reliability. The ability of a radar to sense in all directions, as well as to detect at longer distances and at higher speeds, is key to defeating hypersonic missiles, he adds. 

[Figure 2 | The Raytheon Missiles & Defense Lower Tier Air and Missile Defense Sensor (LTAMDS) radar system for the U.S. Army is designed to defeat advanced and next-generation threats, including hypersonic weapons, or those that fly faster than a mile a second. LTAMDS is the first in the family of radars the company calls GhostEye.]