Northrop Grumman Aerospace Systems, Redondo Beach, California, is being awarded a $17,416,113 modification (P00359) to a previously awarded F04701-02-C-0009 contract to exercise an option. The value of this contract is increased from $1,898,989,472 to $1,916,405,585. Under this modification, the contractor will provide on-orbit operations and sustainment for the Space Tracking and Surveillance System. The work will be performed at the Missile Defense Space Center at Colorado Springs, Colorado; and at Northrop Grumman Aerospace Systems in Redondo Beach, California. The performance period is from April 1, 2019, to March 31, 2020. Fiscal 2019 research, development, test and evaluation funds in the amount of $7,000,000 is being obligated at time of award. The Missile Defense Agency, Colorado Springs, Colorado, is the contracting activity.