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Comment by andrewpolidori | Hacker News Reader

I'm curious to know what is more expensive to roll out capacity for.

starlink launches are expensive but so is doing work under the sea.

Starlink uses wireless connections, be them laser or radio. That just cannot scale in the same way that fiber can. It's an apples and oranges comparison.

Quick note that: yes, but free space laser is a bit different than wireless because bandwidth can be extremely high and adjacent transmitter interference is essentially zero.

It still has to get to/from space at some point on each end.

Couldn't you scale horizontally, e.g. with thousands of satellite base stations scattered across a continent? Then each one could occupy a separate, non-overlapping spatial channel.

Perhaps you could split up and distribute your network backbone over something like that?

That'd require scaling up either the number of satellites or their size (talking to thousands of base stations at once = more power, more antennae) dramatically.

It is possible with micromirror devices to have a single lens on a satellite to send thousands of beams in different directions.

That opens up the idea of N satellites having N^2 bandwidth... Which scales much better than optical fibers, where in general to have double the amount of bandwidth, you have double the cable laying effort.

Current starlink satellites do not have this ability - they can connect to max 3 other satellites I believe, which is pretty much the minimum for a fully connected network.

>> in general to have double the amount of bandwidth, you have double the cable laying effort.

Getting double the bandwidth just means laying a slightly thicker cable, and I do mean slightly. Adding a bundle of extra fiber when laying a cable adds maybe a millimeter to the cable width. The cost of the fiber is almost irrelevant to the cost of the other layers and the effort of placing it. Most cables are therefore laid with plenty of extra "dark" fiber for later expansion/redundancy.

Why can't space optics scale as well as undersea fiber optics?

Because there's a non-space part of the route you have to deal with.

Lasers + clouds = unfun.

Aren't the lasers in space? I don't think the satellites beam lasers to/from earth.

Until you put all of Sweden (and the people they want to talk to, like Estonia) in space, that data's going to have to come down at some point. Fast inter-satellite data doesn't help you if it has to queue to get in/out of space.

Because the "beam" in a fiber is tiny and can be controlled, while the beam between two sats is actually very large and runs in free space. Most of the transmitted energy will always overshoot the receiver, resulting in significant crosstalk issues once multiple sats are in sight of each other. You cannot have two beams running the same path on the same frequency, not in space. But new fiber can be laid down infinitely along identical paths without any degradation.

Both are expensive, for sure, but the undersea cables will be used and paid for by major internet providers, whereas finding customers for Starlink is still proving to be tricky.

On the other hand, submarine cables can work for decades; Starlink satellites each last only very few years.

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