The communications crosslink between the twin Space Tracking and Surveillance System (STSS) Demonstration satellites, built by Northrop Grumman and Raytheon, has shown its effectiveness in transmitting high-precision, real-time missile tracking data to the Ballistic Missile Defense System (BMDS).

The radio frequency crosslink enabled both STSS satellites to simultaneously acquire and track a resident space object (RSO), with only one satellite in communication with the ground Jan. 10. The RSO was a National Oceanic and Atmospheric Administration (NOAA) weather satellite that acted as a surrogate for a cold missile against cold space.

"During that exercise, the STSS ground segment fused 2-D data from each satellite in real time to form a 'stereo' or 3-D picture of the 'battle space' surrounding the NOAA satellite for more than five minutes," explained Doug Young, vice president of missile defense and warning programs for Northrop Grumman's Aerospace Systems sector.

"Combined tracking from both spacecraft lasted more than 17 minutes," he said.

"Stereo tracking of missiles represents a new capability," Young said.

"Such high-precision, high-quality track information allows the STSS demonstrators to close the fire control loop with missile defense system interceptors from space. STSS continues to prove that space sensors provide the most cost-effective and operationally suitable means for global, persistent surveillance and engagement."

While one of the spacecraft was commanded to acquire and track the RSO, the second satellite was commanded to track the RSO via the crosslink. The resulting track data was returned via the crosslink. Track data from both STSS satellites were fused into a 3-D track at the STSS ground station.

Data also was passed in real time from the STSS ground station to Northrop Grumman's External Sensors Laboratory, where missile tracking data is processed and stored. The ground station and lab are in Colorado Springs, Colo.

The Missile Defense Agency is pursuing the STSS Demonstration program as a space-based sensor component of the Ballistic Missile Defense System. The satellites are demonstrating the ability of a space sensor to provide high-precision, real-time tracking of missiles and midcourse objects, enabling simultaneous regional, theater and strategic missile defense.

Data from STSS testing is validating the ability to track cold, midcourse objects and close the fire control loop with BMDS interceptors from space. The STSS satellites provide missile defense sensor risk-reduction concepts to support development and fielding of future operational missile defense satellite constellation.