Hacker News Reader

Comment by IntelMiner | Hacker News Reader

Wouldn't the latency of a sat connection interfere with something real-time like video conferencing?

Current internet satellites with a geosynchronous orbit are about 35,000km above the surface. These Low Earth Orbit satellites will be less than 2,000km above ground, and as low as 300km above. This difference should have a big impact on the current latency number of satellite communication.

[http://www.vsat-systems.com/satellite-internet-explained/lat...]

Edit: Please note that the data packets make a two way trip from the satellite. Many network communications assume a lot of two way communication from client and server, so this decrease in distance should have a big impact.

The best you can physically do is about 2 ms more lag than the fastest ground based system, and that's assuming you're only adding in the transit time from ground station -> satellite -> user.

So it possibly won't be a killer for video conferencing, but keep in mind that the USAF's current system for drone video has 2 seconds of one-way lag. There's three orders of magnitude between what we're currently doing and the physical limit.

SpaceX's system will undoubtedly be better than what is in use today, but even with two orders of magnitude improvement (a HUGE improvement) you're looking at adding 20 ms of lag on top of what you'd already have.

These are very low orbit satellites, not geosynchronous ones. 200 miles, instead of 36,000. Should be much better latency

I think you have your distances wrong. Geosynchronous orbit is 36,000km not miles.

LEO is a range between 300km - 2000km. I suspect the satellites will be on the higher range to reduce atmospheric drag. The IIS has a 400km (250 miles) orbit and it's orbit decays at 2km/month without correction maneuvers.

https://en.wikipedia.org/wiki/Geostationary_orbit https://en.wikipedia.org/wiki/International_Space_Station https://en.wikipedia.org/wiki/Low_Earth_orbit

That's the crazy part, he didn't have his distances wrong. Part of the constellation is planned for an orbit of 340 km which is ~211 miles so close enough. The satellites are only intended to have an operational lifespan of 5 to 7 years. That's not a typo, that also means that given the massive size of the constellation that SpaceX will need to average one launch a month for StarLink with 105 satellites on it. If one of the lower orbit satellites goes dead, without actively maintaining the orbit it'll decay fast enough that it'll passively deorbit itself without risk of it just becoming a derelict satellite for centuries.

His Leo distance was correct, but his geo distance is in the wrong unit of measurement.

Reply on news.ycombinator.com