[elil17]

Each satellite is launched into an orbit that has it fly over certain areas more than others. Most satellites are stationed over the richest countries, so there is very little satellite image coverage of many parts of Africa. These images help monitor everything from weather to crop health. Just like building a road, buying a satellite for your country provides critical infrastructure which can boost an economy.

[iguy]

But is this true? Sure if you want coverage of Siberia you may need your own, but doesn't every orbit cross the equator? I would have thought plenty of satellites cross Ethiopia every hour, although perhaps not bothering to run all their cameras without a customer?

[elil17]

I’m by no means an expert on satellite orbit selection, but from my experience as a consumer the quality and frequency of imagery for an area has to do with a variety of factors - how often the overhead pass occurs in daytime vs. nighttime, how much data capacity they will devote to downloading the imagery, and what angle they point the sensor at.

Here’s a real world coverage map from a European earth observation mission, you can see they were able to select and orbit that gives them daily coverage of Europe but only biweekly coverage of Africa: https://www.researchgate.net/profile/David_Slater12/publicat...

[iguy]

Thanks, nice to see a map. But all those lines which stop at the mediterranean coast... those satellites surely cross north africa at almost the same time of day, it's just not marked because they are turned off? As you say, perhaps limited by daily bandwidth (or perhaps power?)... but that sounds like a commercial consideration.

[mdszy]

Geostationary orbits won't necessarily cross the equator.

[yellowapple]

I'm reasonably sure satellite imaging happens pretty far below geostationary, though. It'd be interesting if we could someday park satellites in geostationary and just stare at a given spot continuously, but lens technology just ain't there yet, last I checked.

[mdszy]

NOAA has a network of geostationary weather satellites.

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

[goodcanadian]

Yes, they will. The only place you can put a geostationary satellite is on the equator. In theory, they stay in position above the selected point on the equator. In practice, they aren't perfectly stationary, and they will move around the designated point, which will, of necessity, cross the equator.

[mdszy]

for the practical purposes outlined in the context of this thread, they do not cross the equator

[iguy]

For the purpose of Africa vs Europe, they can't really be positioned to have a better view of Europe than of Africa.