Stakeholders See a Bright Future for Laser Satellite Communications

The high bandwidth inter-satellite data links made possible by laser-based optical communications technology will revolutionize the satellite ecosystem, and enable a new generation of autonomous vehicles in orbit, a SATELLITE 2022 session heard Monday.

But those developments might be stymied by the absence of standards. Conventional radio frequency, or RF, communications remains the most reliable medium for links to the ground, until technology finds a way to project lasers through rain, fog, or clouds, participants said at the panel “Laser, RF, and the Future of Inter-Satellite Links.”

“It’s as big of a leap forward in technology for the industry as when we first started networking computers with each other,” said Bulent Altan, CEO of laser communications specialist Mynaric, describing optical inter-satellite links, or OISL. “Up until recently, satellites were just singular objects flying in space only talking to the ground, essentially. Now we can have data exchanges in space. We can exchange our information from multiple sensors, from multiple data generators, and [process that and] generate a result in space and then decide where and when we're going to download it.”

In addition to creating a mesh network composed of connected satellites, the new OISL technology would also open new possibilities needed for future space exploration, added Michael Abad-Santos, the new CEO of BridgeComm, which builds laser ground stations. “Eventually we’re going to be getting to the point where people are building major infrastructure in space, and we are going to need ubiquitous, high-throughput data communications in that environment. I think we are an enabling technology for that,” said Abad-Santos.

OISL is also the key to the resilient, hybrid space architecture envisaged by the U.S. military, explained Derek Tournear, director of the Space Development Agency.

“The key capability is the proliferation, is the fact that we can operate hundreds and hundreds of satellites in a proliferated manner,” Tournear said. “That is what gives us the resiliency to where now we can handle attrition in a combat scenario where we can start to lose satellites. That changes the whole mission because now you're not as reliant on a single point failure. But also, that gives you the persistence [to] always have multiple satellites overhead at any given time providing this capability. What actually makes that proliferation possible is the optical mesh network.”

Laser communications had other advantages, too, Tournear added, beyond “the pure amount of bandwidth you can get down on a sunny day.”

“One of the things to keep in mind when you compare RF to optical is, how difficult is it? How much lead time does one need to put up a new ground entry point with a high-data rate RF feed in the continental United States? Compare that to how much lead time one would need to be able to put up a telescope to be able to do the same mission [using optical technology], you will find that the amount of paperwork and bureaucracy you have to go through to get the licensing and approvals and the interference mitigation for RF starts to become very problematic. Whereas with optical, that's a lot easier.”

But the brave new world of OISL also challenges the conventional technical standards employed in networking, noted Hirokazu Mori, chief strategy officer of Warpspace Inc.

“When it comes to inter-satellite communication, [the familiar] TCP/IP [protocol, universally used in internet communications] may not be the most efficient. But there is no ideal almighty protocol, which could be utilized for every means of intersatellite communications — optical, hyperspectral, or RF,” Mori said. The company is talking with its partners about trying to develop new protocols for OISL.

OISL should look to the terrestrial telecommunications industry as a guide for how to develop and deploy standards that could ensure compatibility, said Altan. Eventually, he added, “I would like to see a fiber cable-based network using the same standards as a free space optical network. I think that's where we've got to go with the standards.”

But Tournear was more cautious. SDA has published a standard for optical communications, and established test beds. “So, you can build a unit to those standards and you can bring a development unit or an actual flight unit and demonstrate [on the test bed] that you can plug and play and that you're compatible.”

But Tournear said, “I don't ever want to try to force that [standard] on anyone because I don't know that that's the best standard for everyone to use.”

He said the standard had been developed to be affordable, attainable and to work both in LEO as well as in the air and on the ground. But it isn’t intended to be universal. Rather it is optimized for the affordable mid-range comms network SDA envisaged. “There's going to be a lot of other standards and I don't expect all those standards to be compatible,” he said.

For instance, he noted that commercial ISR providers needed OISL that could provide high bandwidth backbone communication. “Our standard is not the best for that. They are not going to use our standard for all of their optical crosslinks.”

Tournear said commercial ISR providers will fly additional “translator satellites” with two types of comms terminals to link up as nodes to the SDA network. As long as both are IP-based, the network can be interoperable, he said.

Others are taking a more comprehensive approach, noted Gurvinder Chohan, CEO of Canada-based QSTC Inc. “In Canada, we have an Optical Satellite Consortium, made up of universities, government agencies, telecommunication companies, and so forth. We are coming up with a subset of standards for at least the Canadian industry. What we are going to do as an industry together and we have developed a technical roadmap for Canada’s future in optical satellite communications. We are going to develop interoperability protocols.”

He said the consortium has a memorandum of understanding with Japanese and Australian space agencies to work together on the same protocols for optical satellites. VS