EL SEGUNDO, Calif., Dec. 18 -- Raytheon Co. will provide the primary sensor payload for the Space Tracking and Surveillance System (STSS) missile defense system, formerly known as Space-Based Infrared System Low, to prime contractor Northrop Grumman. Both companies have signed a contract, valued at approximately $200 million, for the delivery of sensor payloads. Northrop Grumman was previously awarded an $868 million contract from the Missile Defense Agency to begin developing the STSS system. The Raytheon STSS sensor payload was developed for the continual observation of ballistic missiles in the boost, midcourse and re-entry phases of flight. Composed of an acquisition sensor, a tracking sensor, and processing subsystem, the STSS sensor payload will provide protection from evolving threats to national security, Raytheon said. For more information, visit: www.raytheonmissiledefense.com