DARPA Seeks an Interoperable ‘Space Layer’

Article By : George Leopold

Reconfigurable optical links could connect commercial, government satellites that currently can't converse.

Low-earth orbit is getting crowded, with constellations of communications satellites like the SpaceX Starlink internet service and a growing list of cubesats forming a hodge-podge rather than an interoperable network. What used to be called outer space has been transformed by commercial space entrepreneurs into a new category called “proliferated space.”

In hopes of creating a resilient “space layer,” the Defense Advanced Research Projects Agency is launching an effort to develop an optical communications terminal to link different satellite constellations, forging what the agency hopes will be an “internet of small satellites.”

The Space-Based Adaptive Communications Node, or Space-BACN, seeks to create a cheap, reconfigurable communications terminal that complies with a range of optical satellite link standards. Such a system would connect constellations that currently cannot talk to one another.

With thousands of small satellites expected to be launched into low-earth orbit (LEO) over the next decade, Space-BACN addresses the need for intersatellite communications. “The problem with this growth is that optical communications links are currently engineered to only connect satellites within a given constellation – they can’t dynamically adapt waveforms to communicate with satellites in other constellations,” notes Greg Kuperman, program manager in DARPA’s Strategic Technology Office.

DARPA’s Greg Kuperman.

The lack of satcom standardization has spawned a fragmented, “Wild West” space frontier in which constellations can’t interoperate, government satellites can’t communicate, nor can they leverage emerging commercial capabilities.

Current satellite constellations can be connected via optical crosslinks. “But due to how new these systems are and the cutting-edge technology needed for optical communications in space, there are numerous incompatible standards that prevent satellites from talking to each other,” Kuperman noted.

Hence, DARPA is soliciting proposals for developing new standards-based optical terminals that would form the backbone of its proposed space layer. The goal is an adaptable terminal that can be reconfigured on-orbit to operate across different satellite communications specs.

Along with a streamlined procurement process with the decidedly unbureaucratic “Other Transactions” moniker, the agency is specifying a set of requirements dubbed “100 Cubed.” That includes 100 Gbps to support most optical standards, 100 watts or less operation to reduce power consumption and under $100,000 per terminal to make Space-BACN terminals affordable.

Kuperman said commercial space companies currently offer “ultra-optimized, single-mode coherent systems designed to achieve high-rate communications while lowering cost.” The rub is those cheaper terminals can’t be reconfigured and are incompatible with any other standard.

True to its mission, DARPA is seeking to close the technology gap by funding research to develop new optical links that could mesh future commercial and government satellite constellations into an interoperable global network.

At the component level, the agency seeks to leverage relatively cheap electronics that can function in lower-radiation LEO constellations. With life spans for most LEO satellites shrinking to no more than five years, DARPA also wants the proposed communications terminal to be modular. That would enable rapid insertion of emerging technologies.

“We want this to be an easy decision for someone to place on their system,” Kuperman said.

Ultimately, DARPA envisions a satcom network that creates an optical link to a commercial provider that could then connect with a government satellite. Eventually, the reconfigurable system would be able “connect to an altogether different system that has yet to even be created,” the program manager added.

A DARPA video describing the Space-BACN initiative is here.

This article was originally published on EE Times.

George Leopold has written about science and technology from Washington, D.C., since 1986. Besides EE Times, Leopold’s work has appeared in The New York Times, New Scientist, and other publications. He resides in Reston, Va.

Subscribe to Newsletter

Leave a comment