World-first gigabit laser link between aircraft and geostationary satellite (esa.int)
156 points by giuliomagnifico 4 days ago
icegreentea2 4 hours ago
Here's a paper (from July 2025) on previous steps in this program, getting up the initial testing in flight. Maximum uplink laser power of 20W, though they got good performance all the way down to 2W. The sat has a laser pointing down that was used to help lock on, but it's not clear if it has any meaningful downlink capability, all discussions are about uplink capability. Lots a nerdy details here.
https://www.spiedigitallibrary.org/conference-proceedings-of...
In addition, here's a random paper on the testing performed on the space borne laser terminals - https://icsos2012.nict.go.jp/pdf/1569586689.pdf
This tells us that the laser terminals have a FOV of +/-2.5mrad in acquisition mode (so before lock on), and +/-0.5mrad in communication/tracking mode. This corresponds ~100km and ~20km radius FOV from GEO to surface.
Meneth 10 hours ago
"low-latency links", says the article. I wonder if they consider 500 ms ping to be low, or if they want to replace Geostationary with Low Earth Orbit.
adev_ 5 hours ago
> "low-latency links", says the article. I wonder if they consider 500 ms ping to be low, or if they want to replace Geostationary with Low Earth Orbit.
Directional laser beams are orders of magnitude to jam compared to radio wave. That alone makes it of big interest for military applications, even with 500 ms latency.
There is several known cases where jamming caused the loss of costly military drones.
https://en.wikipedia.org/wiki/Iran%E2%80%93U.S._RQ-170_incid...
Laser comms could prevent that entirely.
shagie 4 hours ago
> Directional laser beams are orders of magnitude to jam compared to radio wave. That alone makes it of big interest for military applications, even with 500 ms latency.
I am reminded of RFC 1217 - Memo from the Consortium for Slow Commotion Research (CSCR) https://www.rfc-editor.org/rfc/rfc1217
2. Jam-Resistant Land Mobile Communications
This system uses a highly redundant optical communication technique
to achieve ultra-low, ultra-robust transmission. The basic unit is
the M1A1 tank. Each tank is labelled with the number 0 or 1 painted
four feet high on the tank turret in yellow, day-glo luminescent
paint. Several detection methods are under consideration:Spoom 2 hours ago
SlightlyLeftPad 3 hours ago
Could these not be jammed by blasting the same wavelength laser at said geostationary satellite?
tiagod 3 hours ago
fidotron 9 hours ago
Getting it to work with one end stationary first sounds like a reasonable development plan. LEO adds a lot of complexity, but with huge benefits.
OTOH the number of engineers that focus on throughput over latency is quite staggering.
IrishTechie 9 hours ago
I guess if your goal is just to stream aircraft telemetry and black box like recordings then latency may not be high on the agenda.
connicpu 8 hours ago
SiempreViernes 9 hours ago
rtkwe 3 hours ago
Geostationary is easier to hit than a LEO constellation like Starlink. With an LEO target you need to switch at least every 2-4 minutes, Starlink ground stations can switch multiple times per minute but that's for obstacle avoidance in the air you'd only have to switch when the current target moves out of LOS entirely.
pottertheotter 7 hours ago
I’ll take 500ms ping for those speeds while temporarily on a plane.
oofbey 7 hours ago
No doubt! I’ve measured literal 5 minute ping times on airplanes. 300,000ms. Where are the buffering the packets!?
raddan 5 hours ago
utopiah 9 hours ago
Nice, if you want a bit more details on the TNO side https://www.tno.nl/en/newsroom/2026/02/airbus-tno-demonstrat... relying on https://connectivity.esa.int/archives/projects/ultraair
tart-lemonade 7 hours ago
> These developments entail a future where travellers could enjoy reliable, high‑speed internet while flying, and where people on ships or in vehicles crossing remote regions can stay connected without interruption.
How reliable/feasible would this be on the ground? From what I understand, shining non-trivial lasers in the sky is a massive liability because of the potential to interfere with aircraft. I don't see anything about the wavelength used, but even if it's outside the visible spectrum, it would still be subject to interference from aircraft when used on the ground or at sea.
joezydeco 6 hours ago
It's being implemented. I thought I saw that Amazon Leo (nee Kuiper) was going to lean on it pretty heavily.
https://www.techbriefs.com/component/content/article/47300-u...
mynameisvlad 3 hours ago
That talks about inter-satellite links (which Starlink uses already). Parent comment asked about ground <-> sat
Jtsummers 6 hours ago
Optical links are being developed for use from fixed ground stations.
https://news.ycombinator.com/item?id=46709548 - Discussion from a month ago with several links for a recent example.
db48x 8 hours ago
Some miniaturization required.
nashashmi 4 hours ago
How does Air force one accomplish their data connection?
icegreentea2 4 hours ago
Air Force One (and all of the other US flying command posts) are basically giant collections of various antennas.
Here's an article from 2017 about (then) recent installation of what were almost certainly satellite communication antenna.
https://www.twz.com/10470/air-force-one-jet-reemerges-with-u...
cm2187 10 hours ago
But that means you need to have a different laser pointed at every single individual aircraft right? Doesn’t really scale.
amelius 10 hours ago
I suppose you can do time-sharing. And use mems-mirrors to quickly move the beam between different targets.
esseph 8 hours ago
Laser TDMA! :-)
eqvinox 8 hours ago
You can probably do phased arrays. (It might already be a phased array.)
mohaine 7 hours ago
Pretty sure phased array LASERs are not yet a thing.
buildbot 7 hours ago
aidenn0 7 hours ago
eqvinox 7 hours ago
voidUpdate 9 hours ago
If starlink satellites get laser downlink, it might work :P
cm2187 2 hours ago
laser downlink to one point, isn't it? Not to 300 moving aircrafts at once.
burnt-resistor an hour ago
I marvel at the ability to track a target in both directions ~40k+ km away while moving quickly (kinematic) considering atmospheric and relativistic effects.
myrmidon 10 hours ago
I'm really curious how the tracking works in such a system, and how "bad" the beam spread is (my impression is that from the diffraction limit alone the beam has to be spread over at least a ~10m radius after travelling 36000km).
Some info on the laser itself would also be very interesting (power? wavelength?).
Really cool project though!
amelius 10 hours ago
> and how "bad" the beam spread is
The spread makes the tracking easier, I suppose.
TimorousBestie 8 hours ago
Perhaps a little, however. Different paths through the atmosphere will perturb the phase of the signal; depending on conditions not all of that ~10m beam width is going to decode with an acceptable bit error rate.
mytailorisrich 8 hours ago
Tracking and actuation is nothing new or particularly challenging, IMHO. It's the laser/optical part combined with throughput at that distance that is the main area of R&D, I think.
xnx 11 hours ago
Impressive! I believe round trip latency would be 0.5 seconds.
1e1a 11 hours ago
That's ~162.5 MB in transit at any time
kevincox 10 hours ago
Excellent for pingfs (https://github.com/yarrick/pingfs)
kipchak 6 hours ago
There's a patent (2017/0280211 A1) for using this as a data storage method, and there was a company called Lyteloop trying to leverage the idea for data storage with estimations for petabytes across constellation.
arethuza 6 hours ago
That could you used like RAM like the delay-line memory used by early computers!
htgb 10 hours ago
Shouldn't it be 1000/16 = 62.5? Impressive nonetheless, of course!
1e1a 9 hours ago
zppln 11 hours ago
Weird.
philipwhiuk 7 hours ago
> Because laser beams spread far less than radio waves, they provide more secure links
Basing your security on laser diffusion seems sus.
Tepix 6 hours ago
These beams are much harder to detect and eavesdrop upon. You increase the difficulty for a remote attacker. I wouldn't stop encrypting the data, however: The Alphasat TDP‑1 has a telescope with an 135mm aperture. The beam diameter is likely to be at least 700m wide according to the diffraction limit.
Schlagbohrer 7 hours ago
It's worth it as another layer of security. The beam width being so narrow means even intercepting it becomes harder. This is more relevant for down-to-earth links where the spot hitting the earth is so narrow it could be confined withing a geographically controlled area, rather than hitting an entire continent like longer wavelengths do.
kube-system 4 hours ago
All security is based on a combination of individually flimsy ideas