DARPA’s vision for satellite communications

As government agencies and private-sector firms like OneWeb and SpaceX launch hundreds of low-Earth orbit (LEO) satellites, the Defense Advanced Research Projects Agency is working on a way to allow seamless communication among government and private-sector proprietary satellites that are currently unable to talk with each other.

The Space-Based Adaptive Communications Node program aims to create an inexpensive, optical communications terminal that could be reconfigured to work with most of today’s optical intersatellite link standards and support future communications platforms. The current lack of communication link standards “results in a fragmented, stove-piped ‘Wild West’ space domain with new constellations that can’t interoperate, government satellites that can’t communicate between one another, and government satellites unable to take advantage of emerging commercial communications capabilities,” Space-BACN program manager Greg Kuperman said.

With a low-cost adaptable communications terminal that could be easily reconfigured on-orbit to communicate across different standards, Space BACN represents a technology leap from the current state of the art, DARPA officials said.

“Traditional government optical terminals for coherent space-based optical communications can cost hundreds of thousands to millions of dollars due to the many precision designed and manufactured components that are hand assembled by highly skilled experts in the field,” Kuperman said. “Commercial space companies, on the other hand, are developing ultra-optimized, single-mode coherent systems designed to achieve high-rate communications while lowering cost. These lower-cost systems, however, are not reconfigurable nor compatible with any other standard.”

LEO satellite constellations like SpaceX’s Starlink not only support broadband for consumers without wireline access, but they also enable search and rescue missions in remote areas or disaster zones. However, even with hundreds of LEO satellites providing imagery and communications, “if teams of rescuers are using different satellite communications systems, they’ll have limited communications ability, Kuperman said in a video. 

The goal of Space BACN, “to not make the perfect solution for everyone, but the good enough solution for most users,” he said. The program aims to develop a “low-cost reconfigurable optical communications terminal that can talk almost any standard and connect systems that otherwise couldn't talk with one another,” Kuperman said. It would allow satellites “to create an optical link to a commercial provider, connect to a government system and then connect to an altogether different system that has yet to even be created.”

Space BACB has three goals, which it describes as 100³: supporting 100 gigabit/sec optical standards, using 100W or less of power and costing under $100K. With LEO satellites expected to last only three to five years, DAPRA expects Space BACN to enable rapid refresh cycles and insertion of new technology as it becomes available.

The program is divided into three technical areas:

1. The design and construction of a low-cost, low-maintenance, reconfigurable optical terminal front end that can cover all wavelengths in the C-band and operate amid the large thermal and vibrational fluctuations that exist space. The terminal must be able to couple light into single mode fiber to support coherent communication modes, traditionally an expensive and labor intensive endeavor. While DARPA doesn’t expect to build a thousand units, it does want a terminal design that can be produced in large quantities.
2. A reconfigurable low-power back-end modem that supports the key protocols and technologies for space-based optical communications. Space BACN wants to combine the best capabilities of FPGA-based software-defined radios and hardware accelerated ASICs to create a low-cost low-power reconfigurable modem, Kuperman said.
3. Reconfigurable terminal components that will allow the device’s front and back ends to be interchangeable “to allow performers to focus on their strengths and enable rapid refresh of system components in the future,” he explained.

DARPA will use a simplified other transactions process for Space BACN so it can lower bureaucratic barriers for proposers, especially those who’ve never worked with the Defense Department or DARPA before.

A virtual information session for Space-BACN program solicitation will be held Sept. 22, via Zoom.gov. A “one-stop” Space-BACN webpage hosting links to the special notice, solicitation, videos, FAQs and other resources is available here. 

This article first appeared on GCN, a Defense Systems partner site.