Feb. 11 (UPI) -- Northrop Grumman Aerospace Systems was awarded an option of $17.4 million for on-orbit operations and sustainment for the Defense Department's space tracking and surveillance system.
On Friday, the Pentagon's Missile Defense Agency awarded the additional funds, bringing the total value of Northrop's contract up to $1.9 billion.
The work will be performed at its headquarters in Redondo Beach, Calif., and at the Missile Defense Space Center at Colorado Springs, Colo., from April 1 through March 31, 2020.
Funding includes $7 million from fiscal 2019 research, development, test and evaluation.
The STSS program was transferred to the Missile Defense Agency from the Air Force in 2001.
Since 2009, two Northrop Grumman-built Space Tracking and Surveillance System demonstrator satellites have been in orbit. The satellites, which were launched together on a single Delta II rocket, track ballistic missiles and other cold objects in space.
The satellite use sensors capable of measuring infrared radiation from space. They include detecting missile launches, tracking missiles from boost into midcourse and communicating with missile defense command and control systems.
The Pentagon originally planned for a 24-satellite constellation but scaled it back for nine to 12 satellites, and renamed it the Precision Tracking Space System. The Air Force, which operates the system, has committed at least $3 billion to develop a follow-on system called next-generation Overhead Persistent Infrared, or next-gen OPIR.
The Missile Defense Agency is evaluating nine proposals for space sensor architectures. The agency has $73 million appropriated and plans to select three.
Space News reported the majority recommend that the sensor layer be placed in orbits close to Earth to identify hard-to-detect targets that include hypersonic glide vehicles.
"We have to be closer to the action in order to do a good job of it," Mike Griffin, the undersecretary of defense for research and engineering, told reporters in January. "We think the best approach is a network of satellites in low orbit. How many, what orbit, all that is to be determined."