COLORADO SPRINGS, Colo.—A little over a year after winning a Space Development Agency (SDA) contract to provide satellites for a low-Earth orbit mesh communications network, Northrop Grumman

[NOC] recently completed the critical design review (CDR), paving the way to begin building its spacecraft for the Tranche 1 Transport Layer (T1TL), the company said on Tuesday.

Northrop Grumman’s contract calls for launch of the first of 21 of 42 T1TL satellites by September 2024, 32 months after contract award. The remaining satellites will be launched about three months later.

Northrop Grumman is demonstrating its ability to be “fast and responsive to the threat,” Blake Bullock, vice president, Communications Systems, Strategic Space Systems for Northrop Grumman, told Defense Daily on April 17 here at the annual Space Symposium. “It’s a game changer for the Defense Department.”

SDA awarded Northrop Grumman contracts for 56 satellites, including 42 for the T1TL portion of the Proliferated Warfighter Space Architecture. The T1TL will be a network of communications satellites that can link with other space as well as terrestrial assets as part of the DoD’s vision of a highly connected battlespace that it sums up as Joint All Domain Command and Control, or JADC2.

The transport layer satellites will include Link 16 datalinks, which are widely proliferated across warfighting assets, advancing the JADC2 vision.

Lockheed Martin [LMT] and York Space Systems are also building 42 satellites each for T1TL. All of the satellites, including Northrop Grumman’s, will communicate with each other via optical communications links.

Northrop Grumman is also building 14 satellites for the Tranche 1 Tracking Layer, which will provide missile warning and tracking information as part of the Proliferated Warfighter Space Architecture. The company recently completed a preliminary design review for the tracking layer.

Under Tranche 0 of the Transport Layer effort, Lockheed Martin and York Space Systems are supplying 10 satellites each to SDA. SpaceX and L3Harris Technologies [LHX] are supplying Tracking Layer satellites under Tranche 0 and L3Harris [LHX] is also under contract for Tranche 1 Tracking Layer spacecraft.

Northrop Grumman is partnered with Airbus Group, which is providing the satellite bus for the spacecraft. Production of the T1TL satellites will begin later this year.