How many satellites will it take today to bring total coverage to anywhere in the world?

Question

Iridium (the failed sat phone company) shot up 66. I heard it can be done now with only 4. 4 is way off of 66.

BTW - Phone coverage

Answer 1

Four is realistic. Communications by satellites is line-of-site. Therefore four in use will suffice. The earth is divided into four quadrants: Northwestern hemisphere, Southwestern, Northeastern and Southeastern. If I'm on the Northwestern and using a sat phone, I hit the sat covering my area, which relays it through the others to the satellite covering the area I'm calling.

Now, if the satellites aren't high enough in orbit you're talking about at least one other to get around the curve separating the eastern hemisphere from the west.

Now that's a mouthful! By the way... there will be a limit as to the number of concurrent connections (calls) that can be made, which would explain why one would launch a larger number of satellites.

Answer 2

Communication satellites are typically launched into low earth orbit (a few hundred miles up) to reduce wattage and lag time. Geosynchronous orbit is around 22,000 miles. Signal time, round trip, is 1/4 second.

You get much better reception with lots of low satellites.

Answer 3

Tough question. Theoretically, it should be possible with three satellites in geosynchronous orbit, but, as we have learned, there are still areas that do not receive signal from any of them, so, I'm afraid that the answer might not be in the number of satellites, but in the power of their transmission, or by improving the methods of transmission.

Answer 4

We can see anyplace in the earth now but not real time for every square foot.