[Torkel]

If I understood it correctly Starlink doesn't send between satellites yet, only sat<->ground. Sat<->sat is a big point of starlink and when they roll that out the latency should go down, especially for starlink<->starlink comms I imagine.

[taneq]

I don't understand how this is meant to lower the latency. Currently:

    ground <--> satellite <--> ground

With satellite links:

    ground <--> satellite <--> satellite <--> ground

How can the latter possibly be faster?

Edit: Thanks for all the responses. I'd been assuming it was a test of Starlink latency only, but if it's Starlink -> ground station -> open internet -> ISP then it would make sense how that would be slower than a pure Starlink connection.

[lultimouomo]

Currently:

ground <--> satellite <--> ground <------------> ground

With satellite links:

ground <--> satellite <--> satellite <--> ground

i.e. the sat-to-sat link should be faster than the ground-to-ground link, on the basis that light transmitted in vacuum goes faster than light transmitted in glass. That's the theory at least.

[fastball]

Plus they're transmitting in a straight line without a lot of switches in between.

[martinko]

More like this:

Currently:

  ground <--> satellite <--> ground <--> ground farther away via legacy infrastructure

With satellite links:

  ground <--> satellite <--> satellite <--> ground farther away directly

[extropy]

Light travels through glass (fiber optics) at 2/3 of the speed in vacuum. So as long as you are skipping some ground links by doing similar length links in space it is faster.

Low altitude orbits mean that the hops up and down can be compensated by faster hops across.

That all of course is not there yet and depends on Starlink implementing the cross sattelite links.

[Havoc]

Current satellites are in a much higher orbit

[Torkel]

This is a good question, I see three main reasons but I may miss something:

1. Hop count is not one on the ground to go same distance.

2. Speed of light is significantly faster in vacuum.

3. The path is potentially straighter for longer distances.

[ls612]

There are some places where there is no ground, say the middle of the Atlantic. Satellite to satellite is important for that.

[iso947]

Yes that’s a few more years before then, and the more sats the more capacity and the lower the latency.

[raducu]

What is the lifetime of a SpaceX satellite?

Judging from their high launch cadence, it seems satellite-satellite communication was just a means to excite the fanboys and motivate their employees, the same way the peddle the Mars stuff.