Two Defense Department officials on Monday outlined how the key technologies  in hypersonic missile defense differ from traditional ballistic missile defense and how offensive developments can aid defensive work.

Hypersonic missile defense “results in different technologies in terms of what you need for ballistic missile defense,” Gillian Bussey, Director of the Joint Hypersonics Transition Office (JHTO) at the Office of Under Secretary of Defense, Research and Engineering, said during Center for Strategic and International Studies panel event on Feb. 7.

“So typically divert, attitude control systems (DACS) [is used] for ballistic missile defense but then for cruise missile defense you’re using aerodynamics forces, control surfaces. So hypersonics forces you really to be in that sweet spot of where more traditional air and missile defenses [both] lie. So you need to have a mix of technologies or a new approach to missile defense.”

Bussey said she spends much of her time in the JHTO on offensive hypersonic weapons and does not envy the Missile Defense Agency’s (MDA) task to defend against them but pointed out several points in science and technology development that can help for both.

She identified technologies the JHTO is working on that have applications on the defense side: infrared window technologies and radio frequency (RF) antenna technology so materials allow the right spectral energy to pass through while protecting a seeker from the stressful thermal environments; aero-optics and better understanding sources of optical distortion for infrared (IR) sensors; having enough divert capability for containment; high-temperature materials and manufacturing; and the potential kill mechanisms of directed energy weapon defenses and how they work on hypersonic missile materials.

Bussey said other areas she knows MDA is interested in is Over The Horizon radars and how hypersonic weapons fly around the radar horizon; a proliferated constellation of IR senses in Low Earth Orbit (LEO); low latency communication for beyond-line-of-sight engagement; possibly using blast fragmentation warheads in defense; systems that require a combination of aerodynamics forces and DACS for higher latitude interception of hypersonic glide vehicles; and predicting intercept points, target locations and maneuvers.

Northrop Grumman graphic representation of how Hypersonic and Ballistic Tracking Space Sensor (HBTSS) satellites are meant to operate and enable targeting of enemy missiles. (Image: Northrop Grumman).
Northrop Grumman graphic representation of how Low Earth Orbit-based Hypersonic and Ballistic Tracking Space Sensor (HBTSS) satellites are meant to operate and enable targeting of enemy missiles. (Image: Northrop Grumman).

She underscored an important factor in the DoD searching for any technologies that can help reduce the requirements of a three-to-one acceleration requirement to intercept hypersonic missiles. Bussey said this requirement could present opportunities for artificial intelligence and machine learning.

She argued there are several opportunities for her office’s offensive developments to aid in MDA’s defense work.

“Well, what has the maneuverability, altitude reach, and speed to hit a hypersonic missile? A hypersonic missile. So there are concepts that can be used to advance offensive designs. The seekers and guidance are different, the booster may be different, but the fundamental aero vehicle can be the same and we’ve seen a number of proposals using what could be an offensive strike weapon used as an interceptor and vice versa,” Bussey said.

She noted MDA is “at the forefront of thinking” about what future hypersonic weapon concepts and designs will be because they need to then defend against that threat and design defenses for threats the U.S. could face in 2030.

Bussey said both offense and defense have similar challenges in materials and manufacturing.

“In fact, some of our key offensive strike investments are funded through MDA because MDA has a need for them.”

Other dual utility offensive and defense developments include a long range kill chain using the proliferated LEO for IR detection and communications, hypersonic vehicle signature management and reduction to help inform designs and reduce signatures, and working to characterize the lethality of directed energy on hypersonic weapons.

“That is something that we’re working together on because we need to understand what that looks like in case our adversaries are developing those threats as well,” Bussey said

Stan Stafira, Chief Architect at the Missile Defense Agency, agreed with her assessments during the panel event.

“We believe countering hypersonic threats is feasible, we’ve looked at it….these threats, hypersonic threats are fast, but we’ve engaged fast threats before. Ballistic threats are just another class of hypersonic threats.”

Safira said MDA looks at hypersonic maneuvering reentry vehicles, hypersonic glide vehicles and hypersonic cruise missiles all together when developing defensive architectures. The agency is trying to not build rigid defenses that target specific systems over classes of targets.

He said the agency is looking at elevated infrared sensors; integrated Command, Control, Battle Managements and Communications (C2BMC) and layered defenses with defenses in both the glide and terminal phases of flight.

Safira described that MDA wants to challenge threats in the glide phase of flight because of how it adds costs to the attacker. Offensive weapons can maneuver in the glide phase, but they are trying to conserve energy while both kinetic and non-kinetic defenses can affect that. Then, if the offensive hypersonic weapon still makes it to the terminal phase, sea-based terminal defenses can more easily intercept it.

While speaking during an American Society of Naval Engineers (ASNE) symposium on Feb. 2, MDA director Vice. Adm. Jon Hill confirmed the Standard Missile (SM)-6 missile currently has a “nascent ability” to defend against hypersonic weapons thanks to its high-speed maneuvering capabilities (Defense Daily, Feb. 3).