Major sub-components of the AN/TPY-2 Ballistic Missile Defense system's radar are being built as backups to keep the radars running during maintenance periods.

Raytheon said the two trailer-sized sub-components it is building are the Electronic Equipment Unit and the Cooling Equipment Unit.

The EEU contains the processors of the AN/TPY-2 system with upgrades that enable the radar to rapidly discriminate threats from non-threats. The CEU keeps the radar operating at the optimal temperature, and distributes power to the system.

Construction of additional EEU and CEU units will enable the Missile Defense Agency to rotate sub-components out of the field for depot-level upgrades without having to temporarily shut down the radar system, Raytheon said.

"The AN/TPY-2 ballistic missile defense radar is a strategic asset which helps protect the people and things that matter 24/7/365," said Raytheon's Dave Gulla, vice president of Integrated Defense Systems' Global Integrated Sensors business area.

The AN/TPY-2 provides long-range acquisition, precision tracking and discrimination of all classes of ballistic missiles and can be deployed around the world in either terminal or forward-based mode. In terminal mode it is the fire-control radar for the THAAD missile defense system.

The contract from the Department of Defense for the two sub-systems is worth $53 million.

Raytheon said it is now constructing the equipment but gave no details as to when they will be delivered.