HUNTSVILLE, Ala. — Top Pentagon officials said here on Wednesday at the Space and Missile Defense Symposium that the Missile Defense Agency and Defense Department overall are working toward space-based missile interceptors while promoting a space sensor layer for both missile defenses and hypersonic defense

The director of the Missile Defense Agency (MDA) Air Force Lt. Gen. Samuel Greaves said the agency “is not averse to looking at space-based interceptors. We are developing options to pursue that capability, if the nation decides that is what we should be doing.”  Greaves was speaking as the morning keynote at this year’s conference.

Lt. Gen Samuel Greaves, director of the Missile Defense Agency. Photo: U.S. Air Force.
Lt. Gen Samuel Greaves, director of the Missile Defense Agency. Photo: U.S. Air Force.

Later, under Secretary of Defense for research and engineering, Michael Griffin, told reporters during a roundtable that Greaves was picking up on Congress’ language in the FY ’19 NDAA that pushes the agency to start developing these capabilities.

The Senate’s FY ’18 defense appropriations bill withdrew statutory flexibility on creating space-based boost-phase missile defenses, directing their development regardless of what the oft-delayed and upcoming Missile Defense Review (MDR) recommends (Defense Daily, July 27).

In the conference committee, the House receded to this provision, but added and amendment that these capabilities will only be pursued if the appropriations bill provides funding for it.

Previously, the White House objected to the provision, arguing DoD is examining several ways to enhance missile defense and directing a space-based intercept layer is “premature at this point and creates a large unfunded mandate” (Defense Daily, June 27).

Griffin said he thinks the idea of space-based interceptors “has been in some ways the victim of unrealistically high, uninformed cost estimates” and naively judged “to cost much more than I believe that they would cost if one actually got down to business.”

While Griffin said he has seen up to 50 cost estimates, none were recent and “I don’t think we know at this point.”

He added he does not see any major technological challenges to producing and placing space-based interceptors in orbit.

“Honestly, a space-based interceptor to go after ballistic missiles in the boost phase is a relatively easy technological challenge. The difficulties we’ve had in the past around that center around policy. It has not been policy of the United States to deploy such systems.”

However, Greaves sounded a cautious note on space-based interceptors two months ago, before the final NDAA bill passed with the space interceptor mandate. Then, he said adding space-based interceptors “would require a significant change in national policy” and “it comes with a fairly large bill behind it” (Defense Daily, June 26).

At the time, Greaves said before these interceptors can come to fruition “there are a number of things that need to happen in parallel to make that, the space-based interceptor, a reality.”

Griffin explained any space-based interceptors, if deployed, would solely be geared against ballistic missiles and not hypersonic weapons.  

The interceptors would go after missiles in the boost-phase of flight, post-boost phase when a re-entry vehicle bus is released but individual re-entry vehicles have not been deployed yet, or they can go after the individual re-entry vehicles.

“A space-based interceptor cannot reasonably go after a hypersonic threat” because those DoD is seeing currently fly within the atmosphere, so any interceptor would itself have to be a re-entry vehicle to survive re-entry to go after hypersonic threats.

Michael Griffin, undersecretary of defense for research and engineering (DoD photo)
Michael Griffin, undersecretary of defense for research and engineering (DoD photo)

“That may not be a bridge too far, but it’s a pretty far away bridge,” Griffin said.

Relatedly, Griffin said it is premature to determine whether any various hypersonic strike weapon programs the DoD is developing have overlapping in capabilities because “I don’t know what’s going to work yet.”

The U.S. is developing a range of capabilities from near-term deployment options to longer-term Air Force and DARPA air-breathing efforts like the Hypersonic Conventional Strike Weapon program (called Hacksaw) and the Air-Launched Rapid Response Weapon (called Arrow).

“Which of those is going to prove to be a winner is an interesting question, that’s why DARPA exists.”

The under secretary repeated a point he made last week: that the U.S. has always been at the forefront of developing hypersonic technology, but “we did not choose to weaponize the results of that research. Our adversaries have chosen to weaponize it. That’s the challenge. We will respond.” (Defense Daily, Aug. 2).

Griffin was notably more concerned about Chinese hypersonic weapons developments than Russia’s. The latter has publicly talked about developing nuclear-armed hypersonic strategic weapons that can maneuver around U.S. missile defenses while the former is working on conventional tactical systems.

“To my way of thinking, the Chinese have been much more thoughtful in their systems development because they are developing long-range tactical precision-guided systems that could be really influential in a conventional fight.”

He said the U.S. must respond to China’s efforts to hold U.S. forward-deployed assets at risk.

Griffin said the only real way to reliably track hypersonic weapons is from space, beyond the horizon limits of terrestrial radars. He said hypersonics are about a factor of 10 dimmer than strategic ballistic missiles so they cannot be monitored from a high orbit.

However, U.S. experience tracking experimental aircraft with the prototype low Earth orbit (LEO) Space Tracking and Surveillance System (STSS) satellites shows it can be done so “this is not a technology challenge, this is a policy-decision-making challenge.”

Griffin underscored the U.S. needs a new space layer sensor layer, regardless of boost-phase missile defenses, and echoed comments by commander of U.S. Strategic Command Air Force Gen. John Hyten during his Tuesday opening keynote.

Hyten said the U.S. must change its defense space architecture and adapt it to newer Chinese and Russian pressures.

The U.S. capabilities are built around “exquisitely capable, very expensive, very vulnerable systems” that were designed and deploy in an era when the U.S. did not have any true space weapon adversaries, Griffin said.

Russia and China are “challenging the assets we have in space because they’re critical to our way of fighting war” so the U.S. must respond, he added.

These changes may include deploying a greater number of less-capable sensors “possibly based off of commercial space developments. That’s one possibility, there are others.”