How many satellites could fit in Earth orbit? And how many do we really need?

News Snapshot:

The number of spacecraft orbiting Earth is rising fast thanks to the emergence of private satellite "megaconstellations." In the last five years, the number of satellites orbiting Earth has more than doubled and will likely double again within a similar timespan, thanks to the efforts of private companies such as SpaceX . But while these spacecraft can provide important benefits, they are also causing multiple issues that are only just being realized by scientists. So, how many satellites can we expect to see in our skies in the coming decades? And — more importantly — how many is too many?...