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Starlink's laser system is beaming 42 petabytes of data per day

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Re: Starlink's laser system is beaming 42 petabytes of data per day

#31

Post by akira2501 »

Symmetry wrote: post #20
ble wrote: post #5

My understanding of the state of the art of inter-satellite optical links is that they have only been used between satellites that are basically in the same orbital plane and in more or less the same orbit. That is, the angle from one satellite to the other changes very very slowly, so that the optics don't have to do much tracking -- and consequently satellites can only form an optical link with other satellites tha…

Right. The Iridium network had communication between satellites in different orbital planes passing each other but that was a pretty unusual capability.

They do have counter rotating planes though, so there are places where two satellite tracks next to each other moving in opposite directions, and these pairs of satellites cannot use the cross plane communication mode.

Additionally, their inter satellite links use regular Ka band radio.

Re: Starlink's laser system is beaming 42 petabytes of data per day

#34

Post by polishdude20 »

mschuster91 wrote: post #6

> The lasers, which can sustain a 100Gbps connection per link > Brashears also said Starlink’s laser system was able to connect two satellites over 5,400 kilometers (3,355 miles) apart. The link was so long “it cut down through the atmosphere, all the way down to 30 kilometers above the surface of the Earth,” he said, before the connection broke. How do these tiny satellites achieve this kind of accuracy and link qua…

Phased array antennas probably have a lot to do with this. You can aim the signal more accurately and faster than any mechanical system ever could.

Re: Starlink's laser system is beaming 42 petabytes of data per day

#36

Post by dfox »

1oooqooq wrote: post #15

[flagged]

> widely visible

Usual selling point in marketing of ground based free space optical links is that it is very hard to intercept. Compared to P2P microwave the beam is significantly narrower and alignment requirements higher and the link loss budget is usually tight enough that when the beam becomes visible off-axis due the weather efects (heavy rain or ridiculously thick fog) the link fails.

On the other hand one can extrapolate from results of reverse engineering of the starlink dish. Everything that goes through the space segment is encrypted and entirerity of the high-level control plane is mTLS authenticated, so one would assume that the inter-satellite links work in similar way. Of note is that software in the dish seems to share large swatches of code with what is not only on the starlink satellites but bunch of other SpaceX embedded linux systems.

Re: Starlink's laser system is beaming 42 petabytes of data per day

#37

Post by okdood64 »

jlmorton wrote: post #24
1oooqooq wrote: post #15

[flagged]

Is this a serious question? You think SpaceX developed the industry-leading orbital rocket, launched hundreds of times to deliver thousands of in-house developed satellites utilizing homegrown, novel argon gas ion thrusters, to develop a global satellite internet system using inter-satellite laser links, their own in-house developed, incredibly inexpensive phased array antenna system, and everything else, and they fo…

This is HN. Everyone here is more intelligent, capable and aware than people who are industry professionals in their specific field.

Re: Starlink's laser system is beaming 42 petabytes of data per day

#38

Post by Cu3PO42 »

edgyquant wrote: post #35
Scoundreller wrote: post #23

So which points are getting “faster than fibre” latency because of this? Extra distance up and down, but make up for it on the long-haul. Won’t beat HF radio though.

Why would we expect faster than fibre?

The speed of light in a vacuum is roughly 50% higher than the speed of light in fiber.

Re: Starlink's laser system is beaming 42 petabytes of data per day

#39

Post by oger »

Scoundreller wrote: post #23

So which points are getting “faster than fibre” latency because of this? Extra distance up and down, but make up for it on the long-haul. Won’t beat HF radio though.

That could already be the case. Round trip time to the ~500km orbit is about 4 milliseconds (+ all other network elements before, after and in between). They claim to have a >5000km link running for significant time. Now think of a fibre link of that length and how many repeaters / routers will be needed due to attenuation and physical constraints. I can clearly see a path where Starlink laser links could be a viable option to subsea cables - at least for some priority traffic...
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