The Space Tracking and Surveillance System (STSS) demonstration satellites, built and operated by Northrop Grumman Corporation, contributed to a successful sea-based missile defense test April 15 by acquiring, after being cued remotely, a target missile during the midcourse phase of its flight.

STSS demonstrators also tracked the target - an intermediate range ballistic missile (IRBM) - from midcourse to termination, according to the U.S. Missile Defense Agency (MDA). Sensor payloads onboard each satellite were designed and built by Raytheon.

The target was intercepted when an SM-3 missile released its kinetic warhead, hitting the IRBM and destroying the IRBM on impact, MDA said.

"This event showed the flexibility of the STSS satellites. They were cued remotely by forward-based radar in the Command, Control, Battle Management and Communications system, which is a key capability for a future operational constellation," said Doug Young, vice president, missile defense and warning for Northrop Grumman's Aerospace Systems sector in Redondo Beach, Calif.

"The event also provided significant risk reduction for a follow-on, operational system. It closely emulated a large part of the communication chain that would be used in an operational engagement," Young added.

The exercise began when the IRBM was launched from the Reagan Test Site located on Kwajalein Atoll in the Republic of the Marshall Islands approximately 2,300 miles southwest of Hawaii. Following the target missile's launch, a forward-based AN/TPY-2, X-band, transportable radar located on Wake Island detected and tracked the threat missile.

According to MDA, the radar sent trajectory information to the Command, Control, Battle Management and Communications system, which processed and transmitted remote target data to an Aegis destroyer, the USS O'Kane.

The destroyer used the data to develop a fire control solution and launch an SM-3 Block 1A missile approximately 11 minutes after the target was launched.

"This was an especially complex test for the STSS demonstrators," said David Bloodgood, Northrop Grumman STSS program manager.

"The timing of the launch required the team to develop target acquisition strategies similar to an operational system. The inter-satellite crosslink was used to communicate with one of the STSS satellites during the test. Additionally, the IRBM was the most threat-representative missile the demonstration satellites have tracked to date."