The Space Development Agency (SDA) wants industry proposals for Tranche 1 of the National Defense Space Architecture (NDSA) to be compatible with two out of three fiber optic wave forms.

The agency plans to release a draft Request for Proposals for Tranche 1 this summer.

“There are three main wave forms used in the fiber optics industry,” SDA Director Derek Tournear told a C4ISRNET forum on Apr. 21. “In essence, our Tranche 1 optical standard is going to say we want you to be compatible with two out of those three, and we also want to see if you can have a software definable radio that does that optical communication that not only allows you to talk to those two protocols, but also our Tranche 0 protocol. The reason we chose that is because that’s what we think the state of the art is for technology to be able to buy very affordable optical cross links that can be mass produced.”

Tournear said that the wave length for Tranche 1 satellites, as for Tranche 0 satellites, will be 1,550 nanometers.

The NDSA will effectively be an optically-connected Internet in space to provide tactical data–low latency communications and targeting information–to military forces in the field.

Tranche 0–the so-called “warfighter immersion” tranche–will consist of 28 demonstration satellites, 20 in the Transport Layer and eight in the Tracking Layer, for military forces to use in exercises and to develop tactics. Tranche 1, by contrast, will be an operational constellation.

Last week, SDA released a Request for Information that seeks industry feedback on the development of optical communications terminals for Tranche 1 of the Transport Layer. Each of the 150 Tranche 1 satellites in the Transport Layer is to have at least three and preferably five or more optical cross links.

“In essence, what we did in Tranche O was we wanted to show the minimum viable product, that we could form a mesh network and send that tactical data directly to the warfighter,” Tournear said. “We chose an optical cross link standard at the time that we knew could affordably be produced based on mostly developments done by AFRL [Air Force Research Laboratory] so we knew there were commoditized optical cross links that we could use, and we used that to define the Tranche 0 standard.”

The backbone of NDSA, the Transport Layer, is to provide the targeting of ground and maritime targets, while the Tracking Layer–the Next-Generation Overhead Persistent Reconnaissance (Next-Gen OPIR) constellation–is to establish effective targeting of advanced missiles. In addition, SDA is working  to aid future intelligence, surveillance, and reconnaissance (ISR) satellites in the Custody Layer to fuse ISR tracking with the Transport Layer to devise the best targeting solution.

SDA is to field 150 small size, weight and power laser communications satellites in Tranche 1 of the Transport Layer by September 2024 and is to field additional tranches every two years. Such mesh network satellites are to provide the rapid targeting of ground and maritime targets to military forces over Link 16. The optically-connected satellites will also supply position, navigation and timing to U.S. and allied forces in GPS-denied environments.

Last August, SDA awarded $281.5 million in firm, fixed-price contracts to Lockheed Martin [LMT] and York Space Systems to build 10 satellites each for Tranche O of the Transport Layer (Defense Daily, Sep. 1, 2020).

The 20 satellites are to launch by September next year.

The 10 satellites to be launched by each company for the mesh network consist of seven in Class A and three in Class B. A Class A satellite will have at least four optical cross links to other satellites in the same or different orbits, while a Class B satellite will have two optical cross links to furnish constant communications among other satellites in the transport layer and a Link 16 transmitter to communicate with front-line forces.

To connect with the NDSA’s Transport Layer, the U.S. Air Force and U.S. Space Force Advanced Battle Management System is to have a GatewayONE waveform translator, a RadioONE software-defined radio, and an ApertureONE common aperture for communications and radar. The latter three methods are to allow the dissemination of data to military forces in the field without Link 16 or another tie to the SDA Transport Layer.

In addition to the 20 Transport Layer satellites for Tranche 0, the latter also will include eight satellites in the Tracking Layer–four by L3Harris Technologies [LHX] and four by SpaceX. Those eight satellites will be an initial SDA stab at monitoring threats from hypersonic and other advanced missiles.

Last week, Tournear said that he views cyber and supply chain threats to the NDSA’s Transport Layer as more significant ones than ground-based direct ascent anti-satellite (DA-ASAT) and laser weapons (Defense Daily, Apr. 14).

SDA believes that the projected hundreds of low-cost Transport Layer satellites–each less than $14 million–will help deter DA-ASAT attacks, while the 1,000-kilometer polar orbit of the satellites will help protect them against ground-based directed energy attacks.