One of the U.S. Missile Defense Agency’s two missile-tracking demonstration satellites on July 23 successfully demonstrated the ability to automatically hand off target tracking data from its acquisition sensor to its tracking sensor, one of the final steps toward calibrating the satellite.

The twin Space Tracking and Surveillance System (STSS) satellites built by Northrop Grumman Aerospace Systems of Los Angeles are designed to demonstrate so-called birth-to-death tracking of ballistic missiles. Launched in September 2009, the satellites have used their acquisition sensors to detect a number of missile launches but their tracking sensors had not previously been tested.

For the first data hand-off demonstration, one satellite’s acquisition sensor observed a firing of a ground-based laser at the Starfire Optical Range at Kirtland Air Force Base, N.M., according to a Sept. 20 Northrop Grumman press release. The sensor created a track file that was transferred to the tracking sensor, which slewed to the proper direction and was able to lock onto the laser’s heat signature, the press release said.

This was one of the final calibration tests in preparation for a birth-to-death missile tracking attempt, Gabe Watson, Northrop Grumman’s vice president for missile defense and missile warning programs, said in a written response to questions. The Missile Defense Agency has said the STSS satellites may be used in any tests of the ballistic missile defense system that they are in position to observe.