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Comment by wtallis | Hacker News Reader

This first batch of satellites doesn't have the planned laser links for communication between satellites, so service in China will only be possible with a ground station in or near China. (The satellites just launched also only operate on two out of the three planned radio bands for connections with the ground.)

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Why would they not include the inter-satellite linkage capability? That doesn't make any sense, given that was a solved problem in the Iridium constellation 20 years ago. That was a huge benefit of Iridium, in that it didn't have to rely on the "bent pipe" of just relaying data between a client and a ground station within the same coverage area. It was literally, "if you could talk to one satellite, anywhere in the world, you would have service".

They need to meet a FCC (?) deadline in order to avoid losing their licenses; probably that functionality wasn't ready in time.

Iridium does inter-satellite linkage with RF, Starlink intends to use laser comms. The advantage being much higher bandwidth, and not having to license the spectrum.

The laser comms are very much on the roadmap, however they were not ready in time for the first launch, and SpaceX has a hard deadline to meet for getting sats up there, so the first generation is going to just bounce your signal back to a ground station. (Which will bounce it to the next visible sat to push it forwards, unless it has fiber.)

Maybe that's why they need 12k satellites, and it also helps with latency if the signal doesn't traverse the constellation.

> it also helps with latency if the signal doesn't traverse the constellation.

No it doesn't. Satellite-satellite lasers can follow a direct route at the speed of light in a vacuum, much like those microwave towers used by high-frequency traders. Done right it'll be lower latency than ground-based fiber optics (which snake over the terrain and only transmit signals at about 2/3 the speed of light).

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