4
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So the GPS system has 31 satellites in an orbit of 20,180 km. Most of the time there are at least 3-4 satellites 'visible' (visible from a signal reception point of view) at any given moment.

The Starlink satellite constellation has many many more satellites (12,000-42,000), but at a lower orbit. To be useful there will need to be at least 1-2 visible at any given time. However there could be more.

Do we know how many Starlink satellite would be visible during normal operation?

*Normal operation as a communication system; not just as the pretty satellite trains you get for a few months after launch.

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  • $\begingroup$ My GPS receiver normally shows signals from more than 6 satellites at once. $\endgroup$ – Jon Custer Aug 7 '20 at 14:41
  • $\begingroup$ @JonCuster Yeah there can be more. Although there are also the European, Russian, Indian and Chinese positioning satellites you may be picking up. The reason a say 3-4 is you need at least 3 to get a lat/long fix and 4 to get altitude as well. Although more is better! $\endgroup$ – DarcyThomas Aug 7 '20 at 20:32
  • $\begingroup$ Thanks for the edit! $\endgroup$ – uhoh Aug 7 '20 at 22:47
  • $\begingroup$ just fyi: From Science Alert's SpaceX Just Launched 57 New Starlink Satellites With Controversial Sun Shades SpaceX already has permission to launch nearly 12,000 satellites, and last year sought additional clearance to put up to a total of 42,000 satellites into orbit. And that's not counting other providers' plans. $\endgroup$ – uhoh Aug 9 '20 at 4:26

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