[mewse-hn]

I've been confused why our Starlink coverage is so good in rural Manitoba, Canada. On HN and elsewhere I heard complaining from Americans about how the service is over-subscribed and over-saturated, but everyone I talk to here raves about the service. I assumed we simply had less subscribers.

This visualization has revealed another reason to me: the satellites hit the northern extent of their orbit and dwell over our province. Who knew orbital mechanics would work out in our favour.

[barbazoo]

I don't quite understand your second reason. Could you elaborate what you mean by "dwell over our province" which would explain improved coverage beyond the fact that there are as you said probably fewer subscribers the satellites are visible from?

[daemonologist]

Starlink has a lot of (most?) satellites at an orbital inclination of 53 degrees to avoid "wasting" time over the poles where few people live while still providing coverage at most other latitudes. This means that at any time there's a higher density of satellites above that latitude than at the equator.

Here's a map of the ISS orbit (similar inclination) over time which shows the effect: https://engaging-data.com/pages/scripts/iss/iss3.png

[barbazoo]

That was very helpful. Clicking on a few satellites and looking at their orbit confirms that. The majority do not go over the poles. Interesting that this also leaves northern Canada, Denmark and Scandinavia with what looks like not much coverage but at the same time there's coverage offered [0] in all those regions.

[0] https://www.starlink.com/map

[jessriedel]

There's probably always going to be issues with getting good coverage of Scandinavia economically because (1) the physics of the orbits means that regions at the same latitude (both Northern and Southern hemisphere) "share" the satellites to an extent and (2) Scandinavia is an outlier in population density at its high latitude. In other words, there are not many other high-latitude countries with which to share the cost of the putting satellites in these inclinations orbits. I believe this is ameliorated somewhat by the US Military's desire for pole-to-pole coverage. I think (?) the near-polar orbit Starlinks were only added later because of this.

[panick21_]

I don't think so. As per sat cost goes down, you can add a few sats on a specific polar orbit that covers that area perfectly. Japan uses that kind of polar orbit.

[jessriedel]

Are you talking about QZSS? That's a Tundra-style geosynchronous orbit, not a polar orbit. Such orbits are much too distant from Earth's surface for them to be usable with Starlink.

https://en.wikipedia.org/wiki/Tundra_orbit

https://en.wikipedia.org/wiki/Quasi-Zenith_Satellite_System

[jessriedel]

Any idea why there is such a discrete separation between the near-polar orbits and the 53-degree orbits? Naively I would have thought that there would be several classes orbits with degrees ranging from ~0 to ~90, with the number in each chosen so that coverage roughly matched the subscriber distribution.

[coryrc]

I think you misinterpreted. Parent poster probably was thinking "fewer subscribers per Earth sq km", but mostly it turns out to be "more satellites per sq km".