LOS GATOS, Calif.−−As detailed recently by Breaking Defense, SA Photonics is helping solve a crucial bottleneck in the low-cost satellite constellations in development in the Department of Defense (DOD). By providing reliable, high data rate communications between satellites,

SA Photonics’ optical intersatellite links (OISLs) are providing a solution to a very complex problem. Our payloads provided to DARPA’s Blackjack program and the Space Development Agency (SDA) Tranche 0 constellation are at the forefront of this advancing technology.

Free space optical (FSO) communication is proving to be the key to a successful low Earth orbit (LEO) constellation, thanks to its high data rate functionality and innate low probabilities of detection or interception. With LEO satellites passing over earth at such high speeds, any given satellite has an extremely short window to connect to a given ground station to offload data. Therefore, OISLs crucially connect satellites to one another, creating a mesh network, allowing constant communication with the ground to all satellites.

SDA is partnered with DARPA on the Mandrake-2 experiment, which will help demonstrate the feasibility of LEO-based optically meshed data networks. This is a risk reduction effort for DOD ahead of the larger full constellations for DARPA and SDA. For SA Photonics, the goal of the Mandrake-2 mission is to demonstrate OISL crosslink capabilities as well as space-to-ground links. The optical communication terminals here will provide 100 Mbps data rates at up to 5,000 km link distance—a speed that will be increased to 2.5 Gbps in later, full-constellation versions.

In particular, OISLs are a key enabler for the Transport Layer of SDA’s seven-layered National Defense Space Architecture (NDSA). SDA’s LEO constellations will serve as the backbone SATCOM infrastructure for DOD’s emerging Joint All Domain Command and Control (JADC3) strategy. SA Photonics’ CrossBeam™ system will be the foundation for its communication payload on these constellations, and therefore on the success of the program.

The first SDA Tranche 0 launch is set for September 2021, and in total will consist of 20 transport layer satellites, and eight missile tracking layer satellites. SDA plans for the NDSA to be a full system of 300 to 500 satellites in LEO. The Tranche 0 constellation is set to be on orbit no later than March 31, 2023