The company was previously chosen to develop the SVs back in August 2018, receiving $2.9bn.
Work is expected to be completed by 31 May 2028, and they will operated by the United States Space Force.
The vehicles – along with two Polar orbiting ones that will be developed by Northrop Grumman – will form the United State’s next-generation strategic missile warning system, the Next-Generation OPIR (Overhead Persistent Infrared) programme.
The US Department of Defense contract also covers engineering support for launch vehicle integration and launch, and early on-orbit checkout for all three of the Lockheed Martin NGG SVs. Also, there is the delivery of ground mission software and ground sensor processing software.
Work will be performed at Lockheed Martin Space in Sunnyvale, California.
See also: Space Force selects Northrop Grumman to provide next-gen missile warning satellites
Image: Lockheed Martin (illustrating Digital Twins technology which will be applied to the SVs)