Comment by mbreese
3 hours ago
In my opinion, the quantity of satellites needed is a function of the height of the satellites. You only need a large constellation because they are moving so fast relative to the earth. This means that each satellite can only see a limited arc at a time. So, in order to cover a large enough area, you have to have multiple satellites following after each other.
The phased array antenna is also a function of this. Each satellite is moving so much that you need to have an antenna following the satellite across the sky.
So, once Starlink decided to have a low earth orbiting constellation (for better latency and bandwidth), the other features (quantity and a steerable antenna) became requirements to have a functional system.
Altitude does impose a lower bound for the number required for global coverage but they have much, much more than geometrically needed. Iridium gets by with about 70 and is only marginally higher.
As for steered terminals, you actually only really need these once you have more than one satellite visible in the sky at the same time. Without that, they’re purely a power efficiency feature.