The Missile Defense Agency currently relies mostly on terrestrial sensors, such as this Sea-Based X-Band Radar. But missile defense leaders said the Defense Department must shift more sensors into space to meet future challenges.

WASHINGTON — As the U.S. military works on developing its next-generation missile defense systems, more of the resources need to be focused in space, experts said Dec. 14.

"It's so important that we make this broader shift from a terrestrial-based system to a system that primarily plays from space in the next couple of years," said Richard Matlock, program executive for advanced technology at the Missile Defense Agency.

The military has long relied on the Space-Based Infrared System, or SBIRS, as a warning against launches of ballistic missiles. But Matlock argued that the U.S. needs to supplement it with a more layered capability in orbit with many different satellites and systems that could not only detect, but track and target a missile through every part of its flight. [The Most Dangerous Space Weapons Concepts Ever]

"The architectures consisted largely of terrestrial sensors deployed on land, deployed on our ships, and interceptors also deployed in silos, in trucks, and in ships," he said. "As we examine the impact of the evolving, more maneuverable, more complex threat on this, we begin to see gaps emerging in the future to our system, which is primarily based on our lack of persistent global sensor coverage."

Those gaps could be addressed by developing a "globally persistent space-based sensor array" that would include radar and electro-optical sensors, Matlock said, at an event hosted by the Missile Defense Advocacy Alliance (MDAA).

Better technology in orbit would also allow missile defense to expand to more stages of an attack. Currently, most of the United States' defense efforts are focused on the middle of a missile's flight, possibly when a reentry vehicle carrying a warhead is approaching its target. But the MDA wants to being focusing on disrupting enemy attacks during the boost phase, sometimes just seconds after a missile is launched.

Matlock said the MDA is hoping to bolster its Space Tracking and Surveillance System(STSS) which is designed to provide the very tracking and targeting capabilities the agency is seeking. At first, the system could be used to extend the range of ground-interceptors, guiding them beyond the sight of radar. But further down the road, a space-based interceptor could be possible.

Missile defense is starting to face new challenges too. Russia and China – as well as the U.S. – have invested various efforts in developing hypersonic missiles that would travel faster than Mach 5 and be very difficult to track and destroy given current means.

"Right now we're examining a number of architectures that would allow us to tackle that challenge," Matlock said. "In the near term, we'll be exploring what sensors we need in order to track those more effectively.… We're exploring, and will be exploring with industry and others in a broader way, what a complete architecture might be and what systems we have today which might be able to address that threat with some modifications, as well as bringing in some of these newer technologies."

Directed energy weapons such as lasers could give the military the capability to combat both hypersonic missiles and to target launches during the boost phase.

"My primary focus right now is in directed energy research," Matlock said. "Our goal eventually is to integrate a high-powered, solid-state laser on a long-endurance unmanned aerial vehicle operating in the stratosphere where the atmospheric disturbance of the aircraft and the laser is significantly reduced."

Sometime before the end of the current fiscal year, the MDA is looking to award contracts to two or more major defense companies for integrating and flight testing an airborne laser demonstration by 2021.

Maj. Gen. Roger Teague, director of space programs for the U.S. Air Force acquisition office, echoed Matlock's comments, saying that "space-based sensing absolutely underlines everything that we try to do to make sure we have eyes on the target."

"It starts in space, our ability to detect those missile threats that might be posed against the U.S. or our allies," he said.

The Pentagon is studying what the right mix of on-orbit capabilities will be, Teague said, ranging from multiple smallsats to hosted payloads on commercial satellites to hardened exquisite military spacecraft. No firm due-date for a plan has been set yet.

"We're evaluating alternatives right now, so any number of different architectures and systems and capabilities are being explored," he said. "There hasn't been any hard decision made on any of that."

But he noted that the Defense Department is beginning to look at what comes after SBIRS.

"We need to start looking at what are those systems that are going to replace it," Teague said. "We're working that very aggressively through the department right now to understand what those future systems ought to be, what they're capabilities might be, and how we might be able to best tap into the emerging technology that we see. In terms of on-orbit, what does that space layer need to look like?"

Neither Matlock nor Teague discussed any specifics about what they expect from an incoming Trump administration, though MDAA founder and chairman Riki Ellison expressed hope that both the Air Force and MDA could see a sizable increase in their budgets.

This story was provided by SpaceNews, dedicated to covering all aspects of the space industry.