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Comment by ergothus | Hacker News Reader

> it is surprisingly easy to communicate with the Earth while aboard a space station in orbit. He suggested astronauts can reach terrestrial phones via satellites around 70 percent of the time

That SHOULD be surprising, but the real surprise to me is that I had never thought about it being hard.

We live in age with enough wonders that I take them for granted. I cant decide if that is amazing or depressing.

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Low Earth orbit isn't really that far away. The ISS is only about a four hour's drive away, if only your car could drive straight up.

Well, you could drive straight up for the 4 hours just so you could wave as it passed you going 70+ times faster than a formula one race car. Alternatively after the drive you can have the worst car accident in history.

Actually, given that, why does the call have so much latency?

Never have I ever been in a call where the latency was dictated by speed of light, since about early 1990s when phone lines went digital. There's an awful lot of routing and switching along the (rather indirect) way, and each hop adds some ms to the mess. Even if the call was only Houston-transatlantic (or worse, transpacific for whatever peering reason)-Netherlands, you'd get pretty bad latency. Add the orbit-relay station-Houston leg, and I assume you'd have a bad time.

Ham radio, on the other hand - now we would be talking significant fractions of c!

In the 1970s (early 80s? my memory is not good) calls sometimes went via satellite in geosynchronous orbit. Those had a lot of latency and didn't last long for that reason. ISS in low earth orbit shouldn't have much latency so long as they have a connection back down to the ground that doesn't involve other satellites.

That's a big if, its orbit can take it pretty much anywhere. But even given a direct downlink, much of the telephone call latency is an artifact of call routing on the ground.

Maybe they're using telecom satellites that are in geosynchronous orbit?

Not sure its true of this one, but some groundstation networks use a bent pipe model, where the radio at the groundstation is doing a bare minimum and then forwarding the data to a compute center located elsewhere. This gives you all the latency on the ground of getting from the physical groundstation site to another location, which could be quite far away, even opposite side of the globe if all the compute is in the same place.

Edit: I see elsewhere in the thread that the ISS is using IP telephony over their geosynchronous satellite link. There's your latency.

> I cant decide if that is amazing or depressing.

I suspect that is because you mix up two different things: the wonders, and human nature. The wonders are amazing. That it is human nature to normalize to the point of taking them for granted might appear depressing. On the other hand, almost everything that we have normalized is mind-blowing and non-obvious when you think about it for long enough. So normalization is also a necessary coping mechanism to get stuff done.

In other words, society wouldn't have progressed much if seeing fire awestruck you every time you saw it.

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