This graphic shows how Project Kuiper would use optical signaling between satellites. (Amazon Illustration)
Ending years of speculation, Amazon has acknowledged that its Project Kuiper satellites will use laser-based links to communicate with each other, and says the system has already been successfully tested in orbit.
Such a system --- known as optical inter-satellite links, or OISL --- passes along data more quickly and efficiently than sending signals down from satellites to ground stations, through fiber-optic cables and then back up to other satellites.
"With optical inter-satellite links across our satellite constellation, Project Kuiper will effectively operate as a mesh network in space," Rajeev Badyal, Project Kuiper's vice president of technology, said today in a news release. "This system is designed fully in-house to optimize for speed, cost and reliability, and the entire architecture has worked flawlessly from the very start."
Amazon said the infrared laser system was tested using two prototype satellites that were launched into low Earth orbit in October. The system was able to maintain data transmission speeds of 100 gigabits per second (Gbps) over a distance of nearly 621 miles (1,000 kilometers) during test windows lasting an hour or more.
Last month, Amazon reported that the initial satellite tests recorded a "100% success rate," but the company held back on mentioning the laser link system until today.
Amazon said the OISL test validated the final component of Project Kuiper's communications infrastructure. "We're excited to be able to support these next-generation OISL capabilities on every Kuiper satellite from Day One," Badyal said.
Stan Shull, the founder of a Bellevue, Wash.-based space consulting firm called Alliance Velocity, said the successful OISL test is a big step forward in Project Kuiper's drive to launch its 3,236-satellite constellation and make broadband internet access available to tens of millions of people around the world who are underserved. Satellite production is scheduled to begin in earnest this month at a factory in Kirkland, Wash.
"Given that Kuiper is ramping up its mass production now to start full-scale deployment in 2024, this is a critical milestone," Shull told GeekWire in an email. "Per their FCC license, Kuiper has to launch about half of their constellation, or about 1,600 satellites, by the summer of 2026. Had this demo mission not gone well, including validating the optical inter-satellite links, it could've put that timeline at risk. Now, it seems like it's full speed ahead for Kuiper."
Although Amazon had considered the existence of OISL system to be confidential information, today's big reveal doesn't exactly come as a shock to close observers.
Four years ago, Project Kuiper's job postings signaled that it was planning to develop a 100-Gbps laser link system. And two months ago, telecom consultant Tim Farrar speculated that Amazon might not be releasing any pictures of its satellites because it didn't want to reveal the presence of laser communication hardware until it was ready to do so.
SpaceX's Starlink network, which has more than 2 million subscribers and a big head start on Project Kuiper, is already taking advantage of optical inter-satellite links.
"Starlink reports it already has more than 8,000 space lasers across its deployed constellation of more than 5,000 satellites, with the ability to enable data transfer of up to 100 Gbps on each link," Shull noted. "This sounds roughly comparable to the capability demonstrated by Kuiper."
Project Kuiper's mission operations team monitors satellite testing. (Amazon Photo)
Other mega-constellation ventures --- including Telesat and Rivada Space Networks --- plan to use OISL systems to facilitate broadband data transmission. And such systems are built into the next-generation missile warning and tracking satellites that are being fielded by the U.S. Space Force's Space Development Agency.
One of the reasons why inter-satellite links are so attractive is that they make it possible for satellites to relay data back and forth over wide swaths of the planet where no ground stations exist --- for example, in the middle of the ocean. Another reason has to do with physics: Because light travels faster in a vacuum than it does through fiber-optic cable, there could be a slight speedup in signal transmission.
But getting the technology right is a tricky proposition. "It requires precision optics and pointing ... and complex orchestration at scale across the satellite constellation and ground stations," Shull said.
Amazon says its satellites will be equipped with multiple optical terminals that can connect many satellites at once. That's an in-space capability that can't be demonstrated with just two satellites in orbit.
"We'll continue to test and improve the system as we deploy more satellites, but initial data from our testing indicates that our design will be able to maintain cross-links between multiple satellites at once," an Amazon spokesperson told GeekWire via email. "That test data – combined with our ability to leverage global AWS cloud infrastructure for network routing – gives us confidence in our ability to operate a next-generation mesh network across our fully deployed constellation."
Resilient communication links are particularly important to government customers. Even before Amazon's first prototype satellites were deployed, NASA awarded $67 million to Kuiper Government Solutions, a division within Project Kuiper that focuses on serving public-sector customers, to demonstrate an in-space optical relay network for satellite communications.
"Amazon's optical mesh network will provide multiple paths to route data through space, creating resiliency and redundancy for customers who need to securely transport information around the world," said Ricky Freeman, vice president of Kuiper Government Solutions. "This is especially important for those looking to avoid communications architectures that can be intercepted or jammed."
Looking ahead, Shull expects to see more constellations taking advantage of lasers, for inter-satellite links and also for satellite-to-ground data transmission.
"It's not only for communication satellites," he said. "With the growing volume and value of remote sensing data from space, laser mesh networks help to ensure that important data insights are delivered back to Earth in a timely fashion. Amazon Kuiper is clearly one of the early leaders with its optical mesh network, and it's great to see this progress. This could be a game changer for both satellite communications and Earth observation going forward."
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