How would that work to, say, Mars? Have satellites filling many, many orbits between the two planets?

cjtrowbridge 2 days ago | parent | next [-]

We already have an interplanetary internet called the NASA Deep Space Network. Understanding it's limitations and challenges is a good way to start thinking about this.

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BizarroLand 2 days ago | parent | prev [-]

Nah, nothing that extreme. The broadcast range and bandwidth of even current technology in space could handle a huge amount of fairly rapid data transfer between the two planets.

It would be more like a handful of satellites, some orbiting earth, some orbiting mars, and then a handful of relay satellites serving as intermediaries.

Don't count on playing e-sports competitively, though.

The lag under ideal conditions would be insane, about 2.5 minutes each way (when the planets are "only" 40 million kilometers apart), but with repeaters and overhead probably closer to twice that.

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macintux 2 days ago | parent [-]

The comment was a few light-seconds. That's a lot of hops to Mars to fill to sustain that coverage year-round.

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snickell 2 days ago | parent [-]

The distance between earth and mars varies between 150 and 2000 light seconds.

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macintux 2 days ago | parent [-]

But carpeting that distance across the entire volume of space between the planets with data centers every few light-seconds apart seems ambitious. A hundred or more data centers in space?

> throw tons of datacenter and compute that's anywhere more than a few light-seconds from the nearest existing datacenter

I think I'm misinterpreting the comment.

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BizarroLand a day ago | parent [-]

It's like the transatlantic internet cable. One really beefy interconnect is more than enough for two halves of the planet to talk.

We wouldn't need to blanket the solar system in data centers to be able to communicate with other planets. We would only need enough connections so that no matter where in their respective orbits they are, there is a line of radio "sight" that is clear enough for high bandwidth communications to work.

I don't have access to the specifics, but I imagine something between 5 and 10 satellite data centers orbiting the sun in between earth and mars would be enough to maintain communications with minimum delay regardless of when in the solar year the comms take place.

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macintux a day ago | parent [-]

At their maximum separation, Mars & Earth are about 20 minutes apart. If we had 10 satellite data centers all in perfect alignment (disregarding the sun, which obviously makes a hash out of things) they'd still each be 2 minutes apart.

Once you take into consideration the sun, plus the fact that the you'd need to cover the full disk to keep all data centers within a few minutes of another one in an unbroken chain back to both planets, I just don't get the math involved here.

But, I'm also terrible at both math and visualization, so I readily concede I may be missing something obvious.

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BizarroLand a day ago | parent [-]

Think of it more like 3 circles.

The inner circle has Earth's orbit in it. The outer circle is Mar's orbit.

The middle circle would be a ring of relatively stationary satellites in between them.

And in the center of all 3 circles is the Sun, which will not allow radio signals to pass through.

I drew a crappy illustration to demonstrate: https://ibb.co/tP2rkzS0

When Mars and the Earth are on opposite sides of the sun, a satellite ring can transmit around the sun and keep the communication lines open.

Having a ring of relay satellites gives you a set distance to transmit from Mars. The satellites can then transmit their received data from the one that is closest to Mars to the one that is closest to Earth, which would then send the data to Earth.

This is helpful for a variety of reasons, but the most important one is that with this setup, even when the Sun is in between Earth and Mars, you could still send data around the sun.

Constant communication, no communications breakdowns. Even if 1 satellite failed for some reason, a bit of maneuvering would allow the others to backfill the gap until it could be repaired or replaced.

Even when Earth and Mars are close together, it would still be smart to use the relay so that the power levels are easily calculated and maintained.

	▲	macintux 17 hours ago \| parent [-]
		That makes sense. I guess I was hung up on “a few light seconds” since that’s more like, what, 5-10 minutes per hop?