Northrop Grumman has been awarded a $19.8 million Navy contract to develop a backup navigation system for submarines when GPS isn't available.

The Inertial Navigation Systems Replacement Inertial Sensor Module (INS-R ISM) "is intended to serve as the U.S. naval fleet's primary position source in the absence of a global positioning system," according to the Department of Defense contract announcement. "The INS-R will provide mission critical ship positioning, velocity, and altitude data to shipboard sensors, combat systems, guns, and missile systems."

If all options are exercised, the contract is valued at $47.8 million. Work is scheduled to be completed by November 2016.