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Comment by oxalo | Hacker News Reader

Has anyone figured out how to deal with the issue of latency for space-based internet? Things like online games and video calls will just not work if the traffic hits space. I could see an ISP offering a service where traffic that needs low latency gets routed on land, while web pages and the like get routed through space. At a cost, of course.

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All of the past versions of "space internet" have been geostationary orbit, which is around 25,000-26,000 miles above sea level. The new iterations, such as SpaceX's idea, is to use many many more microsats and put them in LEO. Low Earth Orbit is closer to 750 or so miles above sea level. Since the ping latency of geostationary sat internet is around 500-700ms, it would be massively less for low earth orbit.

The two technical issues I'm aware of are the sheer number of satellites required for LEO internet, and the fact that you can't point your dish at a single place. There would need to be some sort of actuator or omnidirectional receiver for tracking to satellites at every client site. This makes the installation a bit trickier, but the ping times should be entirely reasonable provided someone gets the funding to put hundreds of satellites into an internet constellation.

The article reads almost like a press release for ViaSat which uses a handful of big geostationary satellites. It even disparages the OneWeb LEO initiative saying it will be too expensive and take too long to build. I think the article was prompted by the dispute between American and Gogo. I'm not sure what it's doing here on HN, doesn't seem that interesting.

As someone who has worked in this industry and seen a lot of these ideas fail first hand - another big challenge is going to be ground entry points. For GEO satellites, each satellite serves many customers and may only need maybe 2-3 (for redundancy) groundstations.

For LEO constellations, each satellite can only see a small portion of customers at any time and will quickly move out of coverage of a single point on the earth, requiring many groundstations.

Alternatively, the satellites can crosslink and eventually hit a groundstation, but these handoffs and trip lengths quickly get back to the ping latencies of making a single trip to GEO.

This actually exists in some countries. E.g. in Europe there are (were?) several companies selling modem/ISDN+satellite bundles. All the upstream and parts of the downstream would travel through land-line while larger downloads would be routed via the satellite. This also saves you from needing to have relatively expensive satellite upstream equipment.

Otherwise, with GEO/GSO satellites there is no way to get below ~280ms round-trip times.

The new services are set to use satellites in low Earth orbit. That only adds a few hundred miles to the distance your data has to travel. The added latency is measurable, but not very high.

The problem with existing high-speed satellite internet is that the satellites are all in geosynchronous orbit, which is about 22,000 miles up. For a roundtrip, your data has to go up to the satellite, down to the ground station, then back up to the satellite and back down to you, for a total of almost 100,000 miles, or more than half a second at the speed of light.

Games and video calls, no, but it should work just fine for things like watching streaming movies.

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