(ORDO NEWS) — Tracking rockets is like picking out one light bulb from a lot of light bulbs, but new technology aims to see them more clearly.
A test flight of a long-range hypersonic glider by China late last year was described in the media as a “Sputnik moment” in the race to develop new super-fast maneuvering weapons. But even at a time when high-ranking US military officials were publicly worried about missiles that are, at least for now, virtually invulnerable, the Pentagon has been quietly making headway in developing an entirely new way to help bring down these weapons.
At the end of December last year, the US Department of Defense Missile Defense Agency (MDA) gave a green light to a pair of contractors – L3Harris Technologies and Northrop Grumman – to move from design to prototyping the Hypersonic and Ballistic Space Tracking Sensor System (HBTSS). This technology is designed to solve one of the Pentagon’s most difficult technical problems: how to detect and track hypersonic glide path vehicles that exploit “dead zones” in today’s radar networks.
Both Russia and China adopted hypersonic glider vehicles in 2019 and 2020 respectively, but the US is expected to deploy comparable offensive weapons only in 2023. Unlike ballistic missile payload trajectories, hypersonic gliding vehicles can maneuver on their way to their target. This makes tracking them extremely difficult.
This weapon begins its journey when a large rocket lifts it to a height close to the edge of space and releases it. The glide paths then deviate to a flatter trajectory – either exiting the atmosphere or staying within it – and sail further without power. Using aerodynamic lift, they fly through the atmosphere towards their target at hypersonic speeds.
This near-space trajectory and the ability to change course allows hypersonic gliders to evade the combination of space and ground-based sensors used to track ballistic missiles. The Pentagon is able to detect the launch, but the hypersonic glider slips out of sight for the remainder of the weapon’s flight due to ground-based radar line-of-sight limitations. As a result, defensive systems have little time, if any, to stop incoming weapons.
HBTSS aims to solve this problem by continuously tracking long-range missiles from launch to impact. It will also be able to relay critical information to ships, aircraft and ground forces, allowing them to fire their own missiles at incoming threats.
The detection system relies on a new network of orbital sensors, which is an important part of the dense and multi-layered constellation of satellites that the Pentagon has already begun placing in low Earth orbit.
Experimental and prototype payloads were sent into orbit last June, with the first operational payloads scheduled to launch in 2022 and 2023. These sensors provide thermal signatures to identify missile launches and will give the US military the ability to track targets,
One of the key components of HBTSS are signal-to-noise algorithms designed to isolate a fast-moving threat on a warm and uneven surface of the Earth. This is a much more difficult task than ground-based radar, which tracks missiles as they move across the cold and featureless sky background.
“Imagine a light bulb moving against a background of many light bulbs, and you have to highlight that light bulb,” says Paul Wloschek, director of missile defense at L3Harris Space & Airborne Systems. “You have to know where it is and how fast it’s flying in order to be able to shoot it down.”
To address this issue, in October 2019, the Pentagon specifically tasked L3Harris and Northrop Grumman (and two other companies that were subsequently eliminated) to develop tracking algorithms sensitive enough to distinguish signal from noise. In late 2020, L3Harris and Northrop Grumman combined their algorithms with compact, powerful computer processors small enough to fit on spacecraft.
Both companies conducted successful “signal chain demonstrations” that confirmed their systems’ ability to detect and track faint targets in the background of interference. The demonstration of the signal chain confirmed the sensitivity needed to support the so-called hypersonic kill chain – discrete actions required in the sequence between target identification and engagement.
Other space assets already provide the US with upper infrared soundings. But the key feature that sets HBTSS apart is the requirement to generate what the Pentagon calls “fire control quality” – tracking data. This is highly accurate information that can be used by ground control systems to target guided interceptor missiles to hypersonic threats.
“Being able to see warm trails from space passing over a warm Earth is really a difficult science,” MDA director Vice Admiral John Hill said at a Senate Armed Services Committee Strategic Forces Subcommittee hearing late last spring. “But we got through it. We showed we can do it on the ground. That kind of potential gives us a global footprint.”
On December 27, President Joe Biden signed into law the National Defense Authority Act for Fiscal Year 2022, which includes $256 million in HBTSS. These funds will be used to continue the development of tracking algorithms, as well as to begin assembling infrared sensors, which are scheduled for launch in 2023.
L3Harris and Northrop Grumman are to deliver two HBTSS prototypes each, including software and hardware. However, Congress is currently deadlocked over appropriations for fiscal year 2022. If the government fails to reach an agreement, HBTSS could be capped at the project’s 2021 spending level of $130 million, which would likely jeopardize the project’s schedule. In this case, the Pentagon can combine existing systems to create something similar to HBTSS,
“HBTSS would be nice to have, but it’s not clear to me that it provides unique features,” says Wright. He explains that the capabilities promised by HBTSS can be achieved without a new space-based program with ground-based sensors placed in the right places.
This may include careful placement of ships equipped with powerful radars to expand defensive zones. “I think it’s a system that I can envision, as the military would like to be able to track these systems all the time – and it could do that tracking outside [ground] radar coverage – but I’m not convinced it’s necessary,” Wright adds.
Victoria Samson, a military space expert with the Secure World Foundation, agrees on the need to track modern threats along their entire flight path, but notes that HBTSS proponents may be underestimating the challenge of addressing this resonant challenge.
“I think it’s much more complex than the proponents claim, and adding hypersonic to the [operations] requirement may be more of a nod to its greater prominence among national security professionals than anything else,” says Samson.
Along with sensors, the Pentagon is rethinking the guided missiles needed to defeat hypersonic gliders. At the end of May 2021, the MDA announced that it had certified the currently deployed Standard Missile-6 missile as the last line of defense for carrier strike groups for use against hypersonic glide path vehicles.
And in November 2021, the MDA commissioned three companies to develop designs for a new weapon called the Glide Phase Interceptor designed to combat hypersonic threats. Thus, between Lockheed Martin, Raytheon and Northrop Grumman, there will be a three-way competition for the right to create a new weapon within a decade.
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