WASHINGTON — Before its first satellites are on orbit, the Space Development Agency is reaching out to industry for feedback on how it should upgrade its communications standards for its second generation of satellites.

Established in 2019, the agency was charged with developing the National Defense Space Architecture, a proliferated constellation to eventually be made up of hundreds of satellites mostly operating in low Earth orbit. The backbone of the architecture is the transport layer, a mesh network on orbit connected through optical intersatellite links. The transport layer will allow the DoD to rapidly move data through space, and will be the glue that will connect the services’ various Combined Joint All Domain Command and Control networks.

“The whole idea is to be able to move data as rapidly as possible to get that tactical information directly to the war fighter,” said SDA Director Derek Tournear at the annual C4ISRNET Conference. “So what the transport layer consists of are hundreds of satellites that form a resilient optically interconnected mesh network that will pass data directly to existing tactical data links. So what that means to the war fighter is the following: I can now move data from a targeting cell that could be located CONUS or ideally that targeting cell will actually form a target onboard on the satellites and I can send that data down directly to an existing tactical data link on a weapons platform or on a weapon itself.”

SDA is using a spiral development approach to build out the NDSA, putting up new tranches of satellites every two years. The first set of 28 satellites — tranche 0 — will begin launching in 2022 and provide a war fighter immersion capability. Tranche 1 will have closer to 150 satellites and will be an operational system.

SDA adopted standards for its tranche 0 optical intersatellite links, but it’s already looking to change those standards for its tranche 1 satellites, which are set to be launched beginning in 2024.

“Now in essence what we did in tranche 0 was we wanted to show the minimum viable product was that we could form a mesh network and that we could send that tactical data directly to the war fighter,” Tournear said. “We chose an optical crosslink standard at the time that we knew could affordably be produced based on mostly developments that were done by AFRL [Air Force Research Laboratory] at the time.”

That standard made sense for the 28 satellites in tranche 0 the director noted. It made less sense for the scale of tranche 1, which will see about 150 satellites added to the constellation.

“Tranche 1 is a completely different ballgame,” Tournear said. “That’s our initial war fighting capability We will be able to provide regional persistence to the war fighter with this low latency comm. So now if we’re looking at 150 satellites and we’re looking at, you know, something on the order of three to five optical crosslinks per satellite and we want those crosslinks to not only be satellite to satellite but satellite to air, satellite to ground and satellite to air and maritime assets, we had to start to look and say, ‘Okay now we really need to look at the optical comm standard and say, what is industry doing?’”

On April 16, SDA issued a request for information seeking industry feedback on an optical communication standard for tranche 1. Tournear said that standard is expected to hold through tranche 2 with minimum changes and backward compatibility.

“Starting in tranche 3, that’s when we will look and fold in the lessons learned from tranche 1 and any new technology that’s been developed and any new threats that have come online and and have basically a revamp, so tranche 3 will likely be quite a bit different than tranche 1 and 2,” said the director.

The new tranche 1 standard will also be the standard used to tie commercial and Space Force satellites into the SDA mesh network. Tournear said he expects Space Force systems to connect to the transport layer via optical intersatellite links in tranche 2. Commercial capabilities are expected to tie in even sooner.

In addition, Tthe agency is working with three to four companies to ensure their satellites can connect to the transport layer via optical intersatellite links, he said. Those commercial satellites will form the custody layer, an intelligence, surveillance and reconnaissance capability that will provide overhead satellite imagery for tactical targeting. The agency is also talking with commercial services that could provide high bandwidth data backhaul in case the architecture was disabled.

SDA is expected to order its tranche 1 transport layer satellites this summer. Responses to the optical communications RFI are due April 30.

Nathan Strout covers space, unmanned and intelligence systems for C4ISRNET.

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