DoD Launching Experiment For Space-Based Hypersonic Missile Detection

TR_123456 · Aug 10, 2021

SDA and MDA need to characterize the Earth's infrared background -- which has "a lot of complex shapes to it, clouds, land and stuff like that" -- in order to "pull out the dim signal" of a hypersonic missile, an SDA official explained.

Northrop Grumman’s Cygnus spacecraft. (Northrop)

WASHINGTON: The Defense Department’s Space Development Agency (SDA) today plans to launch an experimental payload, developed jointly with the Missile Defense Agency (MDA), to study the infrared background created by the Earth.

The experiment, called Prototype Infrared Payload (PIRPL), is foundational for developing DoD capabilities to detect and track dim, fast-flying hypersonic missiles, SDA officials said in a briefing last week.

The PIRPL, a multispectral infrared camera, is one of the numerous payloads headed for the International Space Station (ISS) as part of Northrop Grumman’s Cygnus NG-16 commercial cargo ISS resupply mission, contracted by NASA. It also was built by Northrop Grumman, under a $38 million joint SDA-MDA contract.

NG-16 lift-off, on the firm’s own Antares rocket, is slated to take off at 5:56 pm EDT from NASA’s Wallops Flight Facility in Virginia, according to a Northrop Grumman press release. (The launch, coincidently, coincides with today’s opening of the Army’s annual Space and Missile Defense Symposium in Huntsville, Alabama.) It is expected to dock with the ISS on Aug. 12.

The primary objective of SDA’s “Tracking Layer” of small satellites in Low Earth Orbit (LEO, between about 100 and 2,000 kilometers in altitude) is to detect and track fast-moving hypersonic missiles, SDA officials said.

The Tracking Layer involves pairing SDA’s new a wide-field of view infrared sensor and MDA’s new medium-field of view Hypersonic and Ballistic Space Sensor (HBTSS) to track both traditional ballistic missiles and the harder-to-see hypersonic cruise missiles in flight. DoD has green-lit the Sept. 2022 launch of 10 Tracking Layer sats — and 20 satellites in the “Transport Layer” of data communications relay satellites — collectively called “Tranche 0” of SDA’s National Defense Space Architecture.

PIRPL, however, is not designed to do actual missile tracking. Instead, its goal is to characterize the “bright” infrared background of the Earth in order to feed into the new detection and tracking sensors.

“To be clear, PIRPL is a demonstration to collect information about what the Earth infrared backgrounds look like that will help inform how we would field the Tranche 0, and beyond, systems, and how we would fly them,” an SDA official told reporters on background.

SDA and MDA need to characterize the Earth’s infrared background — which has “a lot of complex shapes to it, clouds, land and stuff like that” — in order to “pull out the dim signal” of a hypersonic missile, the SDA official explained.

This can done through processing of the images via a technique known as clutter suppression.

“So, that means I’m trying to subtract the unwanted background from the picture that I took and see what’s left,” the official elaborated. “And what’s left is going to show me, was there a bright infrared source that might be a missile or it might be a forest fire, or might be a meteor. Of course, I’m interested in the ones that might be missiles.”

Clutter suppression is used by current missile detection and tracking satellites, such as the Space Based Infrared System (SBIRS) satellites, which reside in Geostationary Orbit (some 36,000 kilometers up) where they essentially “hold still” over one spot on the Earth, the SDA official explained. The challenge in LEO, however, is that both the target missiles, especially hypersonic ones that fly at speeds of Mach 5 and above, and the satellites themselves are moving extremely fast.

“When you try to do that activity from a fast moving LEO satellite — several kilometers per second relative to the Earth’s surface — you have a much harder problem because not only might the clouds have moved, but [also] your satellites,” the SDA official said.

PIRPL will take infrared “pictures,” primarily from within the Cygnus module docked to the ISS for some three months. But when Cygnus departs the ISS, the camera will be ejected into space to take more pictures until it finally tumbles back through the atmosphere and burns up, the SDA official said. (The Cygnus spacecraft itself also eventually will deorbit and be destroyed.)