The U.S. Space Force’s Space Development Agency (SDA) is targeting launches of its Tranche 2 data communications Transport Layer (T2TL) low Earth orbit (LEO) satellites in 2026 as part of the future Proliferated Warfighter Space Architecture (PWSA).

“The T2TL establishes initial launch capability (ILC) in September 2026 with the launch of a plane of T2TL-Beta SVs [space vehicles] and continues with an approximately year-long, monthly launch campaign involving the multiple T2TL variants,” SDA said in an Apr. 28 business notice. “As these SVs are placed into their insertion orbits, SDA will undergo a continuous checkout and commissioning process to prepare Tranche 2 for acceptance into operations conducted out of the Operations Centers (OCs) at Grand Forks, AFB (OC-N) and Redstone Arsenal, AL (OC-S). These OCs will be operational in time to support Tranche 1 – the PWSA’s initial warfighting capability for BLOS [beyond line-of-sight] targeting and data transport and advanced missile detection and tracking. Tranche 1 establishes ILC in September 2024 and will begin transitioning SVs to operations in 2025. As such, the Tranche 1 system will be conducting mission operations in the OCs at the time that Tranche 2 achieves ILC.”

SDA plans to issue a solicitation for Tranche 2 Transport Layer Alpha this summer, and, for missile defense, a Tranche 2 Tracking Layer solicitation in the fall (Defense Daily, Apr. 20).

The Tranche 2 Transport Layer (T2TL) has three parts. The SDA last month released the solicitation for the first piece, called Beta. Responses are due by May 10. The SDA anticipates three vendors for 72 total satellites for Beta. The primary mission for the Beta satellites is UHF and S-band tactical satellite communications using current radios. Beta is also to provide a mesh network with laser communication, laser communication to the ground, and Ka-band communication to the ground.

The next solicitation, for 100 Link 16-enabled T2TL Alpha satellites, is to be released this summer.

SDA plans to issue a final T2TL Gamma solicitation early in 2024. Those satellites are to include UHF and S-band and enhanced, anti-jam waveforms.

In February last year, SDA announced nearly $1.8 billion in awards to Lockheed Martin [LMT], Northrop Grumman [NOC], and York Space Systems for 126 prototype satellites for the Tranche 1 Transport Layer–the SDA’s first stab at fielding operational satellites to provide resilient, high volume, minimal lag time communications for military missions (Defense Daily, Feb. 28, 2022). Each contractor is to build 42 satellites to be ready for launch by September next year. Lockheed Martin won $700 million, Northrop Grumman $692 million, and York Space Systems won $382 million.

In addition, SDA said last October that York received a $200 million contract through 2031 for 12 Tranche 1 Demonstration and Experimentation System (T1DES) satellites to demonstrate tactical satellite communications and Integrated Broadcast Service from LEO.

Making the Tranche 1 ground segment “multilingual” to make sense of the data from various contractors’ satellites in the Tranche 1 Transport Layer, Tracking Layer, and T1DES is a significant technical challenge, an SDA official said in May last year upon SDA’s $324.5 million award to a General Dynamics [GD] and Iridium Communications Inc. [IRDM] team for the Tranche 1 ground operations and integration (O&I) segment (Defense Daily, May 27, 2022).

The General Dynamics/Iridium team is to provide the necessary network operations and command and control for SDA satellite operations centers at Grand Forks AFB, N.D., and Redstone Arsenal, Ala., to tie together the Tranche 1 satellite constellations.

The Transport Layer, Tracking Layer, and T1DES contractors are to develop NEBULA operations – Vendor Architecture (NOVA) software suites for running the companies’ specific satellites from the SDA satellite operations centers, and General Dynamics is developing the “SUPERNOVA.”

The latter “ties all of the NOVAs together and allows them to be operated as one,” SDA Director Derek Tournear said last October. “The interface between that NOVA and SUPERNOVA is owned by GD, and that is how we can respect the proprietary nature of the vendors, but keep the ability to have this vendor-agnostic solution that GD can use to operate the entire Tranche 1 family.”

“Only SUPERNOVA will be able to see all the different NOVA solutions,” Tournear said.

In the Apr. 28 business notice SDA said that it intends to establish a government Test and Checkout Center (TCC) to speed the fielding of Tranche 2 at the operations centers in Grand Forks and Redstone Arsenal.

“The exact location of the TCC is not yet determined, however, SDA anticipates that it will be near, though not collocated with, one of the OCs,” the notice said. “SDA envisions the ‘exit state’ of the commissioning phase at the TCC to be very similar to the ‘entry state’ to the OC – a fully-functional, optically-interconnected, and networked plane of SVs commanded and controlled by Offeror personnel using their NOVA ground system with verified interfaces and connectivity with SUPERNOVA.”