DoD experiment flying to International Space Station to collect data for missile-tracking sensors

The infrared imaging payload — called PIRPL (short for prototype infrared payload) — is a 110-pound multispectral camera that will collect data on the low Earth orbit environment. A Northrop Grumman spacecraft scheduled to launch Aug. 10 on a resupply mission to the International Space Station will deliver 8,200 pounds of crew supplies, hardware and science experiments. Among the science payloads on board Cygnus NG-16 is an infrared imaging sensor that will collect data on the low Earth orbit environment. The Pentagon’s Space Development Agency will use the data to develop thermal sensors that can detect hypersonic missiles and other advanced weapons while in flight. Cygnus NG-16 will fly on a Northrop Grumman Antares rocket from the Mid-Atlantic Regional Spaceport at NASA’s Wallops Flight Facility in Virginia. It is scheduled to rendezvous with the ISS on Aug. 12. The infrared imaging payload — called PIRPL (short for prototype infrared payload) — is a 110-pound multispectral camera also made by Northrop Grumman under a $13.8 million contract from the Space Development Agency (SDA) and the Missile Defense Agency. This is SDA’s first experiment in support of its Tracking Layer, a planned constellation of small sensor satellites in low Earth orbit. “Upon arrival at the Space Station, PIRPL will begin collecting infrared data and expanding detection capabilities that will aid in the development of algorithms for the next generation of tracking satellites,” Northrop Grumman said Aug. 9 in a news release.

For the NG-16 mission, the Cygnus spacecraft will launch aboard the Northrop Grumman Antares rocket, carrying approximately 8,200 pounds of supplies, equipment and experiments for the International Space Station. Credit: Northrop Grumman

PIRPL will gather imagery through the entire NG-16 mission expected to last about three months. After Cygnus leaves the space station, PIRPL will be released from the spacecraft and briefly operate in free flying mode so it can collect more data from different angles before it burns up in the atmosphere, an SDA official said during a call with reporters. 

The imagery “will help us understand what Earth infrared backgrounds look like from this type of orbit,” the SDA official said.

Current U.S. military missile-warning satellites have powerful infrared sensors that can detect ballistic missile launches from geosynchronous orbits 22,000 miles above Earth. SDA’s Tracking Layer satellites will be in lower orbits at about 600 miles so the agency needs sample data to develop algorithms that can identify targets amid the clutter.

“One of the objectives is to look at what we can do from LEO orbits which are fairly new for these types of missions,” the official said. “We need to understand what the atmosphere, clouds, earth surface, land and ocean all look like at various times of day and night.”

SDA and the Missile Defense Agency want to “show that we can do those missions at a lower Earth orbit, that we are able to get much closer to the threats,” the agency official said. Another reason for the PIRPL experiment is to test how sensors perform when they’re moving at very fast speeds in low orbits, compared to current staring sensors on geostationary satellites.

“We call that a complex background,” the SDA official said of low Earth orbit. “We need to check whether LEO data can be processed successfully to do the same missions that we do well in high orbit.”