The Space Development Agency (SDA) is preparing to issue solicitations for Tranche 2 of its proliferated Low-Earth Orbit (LEO) constellation, with a solicitation for Tranche 2 Transport Layer Alpha set for this summer, and Tranche 2 Tracking solicitation to be released in the fall. SDA Director Derek Tournear spoke about the solicitations on Wednesday during a media briefing at Space Symposium. 

The Tranche 2 Transport Layer (T2TL) is broken up into three pieces. The SDA recently released the solicitation for the first piece, called Beta, with responses due by May 10. The SDA anticipates three vendors for 72 total satellites for Beta. The primary mission for those satellites is a UHF and S-band transmission for tactical satellite communications that work directly with existing radios. They will also provide a mesh network with laser communication, laser communication to the ground, and Ka-band communication to the ground. 

The next solicitation, for T2TL Alpha, is expected to be released this summer. This will be for 100 satellites and likely awarded to two vendors. This will have very similar capabilities to the Tranche 1 Transport layer satellites with Link 16 capabilities, Tournear said. 

Tournear said the final T2TL Gamma solicitation will likely come out early in 2024. Those satellites will also have UHF and S-band capabilities, along with enhanced waveforms for anti-jam capabilities in a contested environment. 

In addition, the Tranche 2 Tracking solicitation is expected to be released this fall. Tournear said a warfighter council to approve the SDA’s requirements is set for September, and he expects to release the solicitation afterward. 

The SDA just saw the launch of its first 10 satellites for Tranche 0, the demonstration tranche. The agency wants to test Link 16 capabilities from space with Tranche 0, but does not yet have approval from the Federal Aviation Administration (FAA), Tournear confirmed Wednesday. 

He said the SDA is in negotiations with the FAA plans for 60-day temporary frequency authorization to do testing over Eglin Air Force Base, Fla., instead of going through full certification testing of the electromagnetic compatibility features of Link 16 terminals. 

“That could take many months before we get through the full compatibility functions. That could push [us out] many months,” Tournear said. “We’re trying to negotiate with the FAA to give us that temporary frequency authorization before the full EMCF testing is done. Otherwise, it will delay our test. Until we get until we get approval on that path forward, we haven’t locked in any specific Link 16 demos because we don’t know the timing.” 

Looking forward, the SDA is also looking into satellites that “translate” between commercial constellations providing imagery and sensing or communications, and the SDA satellites. 

“We’re working with mission partners on what it would take to fly satellites that do a translation between commercial constellations — those could be commercial constellations, providing ISR, like a Maxar constellation, or commercial constellations providing comms, like a Starlink constellation,” Tournear said. “We are investigating what it would look like to put up a payload that talks to both our Transport layer and those. We haven’t solidified any contract yet.”