SpaceX satellites built for the US Space Development Agency demonstrated direct satellite to satellite laser communications in space using optical terminals compliant with military standards.
U.S. Space Development Agency (SDA) director Derek Tournear said Sept. 4. that two SpaceX-built satellites successfully exchanged data using optical communications terminals.
The satellites, part of SDA’s Tranche 0 experimental spacecraft in low Earth orbit.
“We had not previously demonstrated laser communications,” Tournear said at a DefenseNews conference. He reported that the data exchange occurred on September 3, with the satellites establishing a connection in under 100 seconds and maintaining it for several hours.
SpaceX has connected all of its 6000+ commercial Starlinks via direct laser communication. By the end of 2023, SpaceX Starlink already had over 9000 lasers connecting its Starlink satellites with 100 GBps communication.
SpaceX engineer reported that SpaceX commercial systems achieved over 99% link uptime on a fleet of 100G space laser inter-satellite links in LEO. The January 2024 presentation offered an overview of the design, mass manufacturing, and operational challenges confronted in the development of SpaceX’s global satellite laser mesh operating in Low Earth Orbit (LEO). The Starlink network consists of over 5,000 free-space optical communication terminals, each achieving data transmission rates of 100Gbps and link uptime over 99%, enabling high-speed global internet coverage.
SpaceX is constantly upgrading its own Starlink satellites with better laser transceivers and will make them available to third-party satellites. SpaceX will use lasers directly down to Earth for ground-based transceivers.
Among currently active inter-satellite communication systems, Starlink is by far the most numerous and with the highest bandwidth, reaching over 42 Petabytes per day across its over 9000 space lasers (at the end of 2023) for a 5.6 Tbps throughput. SpaceX likely has over 13000 space lasers in orbit communicating. The communication rate likely has increased to over 60 Petabytes per day.
Since these satellites form a mesh network with their 100 Gbps laser transceivers, a big part of using it efficiently is to route any data with the least amount of latency while taking into account link distance (maximum of 5,400 km), link duration (up to multiple weeks) and presence of other Starlink satellites before they become within reach. With this complex mesh in LEO, this also means that a very high uptime can be accomplished, with a claimed 99.99% due to rapid route changing.
The successful test involved two of four SpaceX satellites equipped with Leidos infrared sensors and Tesat terminals. Tesat-Spacecom is a subsidiary of Airbus.
This demonstration addressed doubts about SDA satellites’ ability to form an optical network in low Earth orbit. It follows a 2021 test conducted with the Air Force Lab and DARPA.
Here is a 2021 paper talking about the Starlink laser communication netowrk.
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Cool for the prospect of orbital datacenters and a growing space economy in LEO.
Besides they need this technology for creating an interplanetary Starlink. Something de rigueur and required if they want to send people to Mars.
Laser communication has some interesting advantages over other forms of extreme high frequency radio. At “radio” frequencies ‘the signal “bleads out”, but also can be intercepted. Either by active interception sending radio signals into a radio transmission, and sorting out what’s left. One way to “harden” communications is to make a sentence incongruent. AKA, what’s said, is contextually non-sensical. But this only works so long. After all, trying to convey factual information can only be contained within gibberish, rhyme, music, or other abstractive linguistics’ for so long. It could be code. Or sometimes, wacko people say whacko things. This happens more often then most of us know, let alone would be comfortable with.
Laser communication has the disadvantage but also advantage of being “line of sight”. This makes it incredibly difficult to detect, let alone “listen to”.
I wonder if there is another aspect to the starlink network. Elon Musk’s ideas are usually very far out. Could the combination of starlink and starship make the star wars initiative of the 80s finally feasible? I mean if you could take out ICBM in flight then you make the treat of existential nuclear war less likely.
Come on… Starlink satellites cannot generate or direct anywhere near enough power to use their comms laser as a weapon. We’re talking 100s of kilowatts of laser power to knock out an ICBM. More likely in the megawatt range.
That’s not what I implied, starship would be used to put the big lasers in orbit. But you need very accurate tracking to determine the position and trajectory of the missile so if you add radar or Infrared sensors to the same satellite you probably have a very accurate system.