Northrop Grumman-developed two demonstration Space Tracking and Surveillance System (STSS) satellites have retired after successfully completing their missions.

The STSS satellites were launched in 2009 by the Missile Defense Agency (MDA) to detect and track missile launches.

The performance of the two demo satellites helped in gaining new insights and will support the development of future operational missile warning and tracking systems.

Northrop Grumman overhead persistent infrared and geospatial systems vice-president Sarah Willoughby said: “Launched in 2009 and expected to operate for four years, these demonstration satellites outlived their design life threshold three times over.

“Now we are applying what we learned from STSS for future systems to keep America and its allies safe.”

The STSS experimental spacecraft demonstrated their capability to identify short, medium, intermediate and intercontinental-range missile launches and track them from boost phase to midcourse.

The satellites also transmitted the track data to command and control systems for target interception.

During the mission period, the satellites were used to track targets, identify real threats, guide interceptors and monitored space missions among others. They were also associated with one of MDA’s integrated Ballistic Missile Defense System flight tests.

Headquartered in Virginia, US, Northrop Grumman is an aerospace and defence technology company with around 90,000 employees.

Recently, the company delivered the first of three RQ-4B Global Hawk uncrewed air vehicles (UAVs) to Japan.

The UAV reached Japan in a non-stop transpacific flight of around 18.7 hours.