Sats

So when you are bored at work, you end up in weird places. (I know, you are nervous about clicking that link.)

I never appreciated the scale difference between low earth orbit satellites and geostationary ones. I noticed that it seems sort of crowded out there. "How many satellites can actually fit in geostationary orbit?" Well, figuring out that problem seemed much more interesting than examining a huge database of misclassified Accounts Payable.

Here's what I came up with from my searching, rough back of the envelope:

geosynch orbit = 35,600 km
earth width = 12,800 km
circum @ orbit = 263,900 km
+- latitude = 10 dg
+- latitude (tan 10 dg) = 7,400 km
+- altitude = 200 km (higher than that is where sats go to die)
+- positioning of sats = 35 km (margin of error)
min distance between sats = 10 km (made that up)
passing lane east = 35,600 + 35 + 10 + 5 = 35,650-35,800 km
passing lane west = 35,600 - 35 - 10 - 5 = 35,400-35,550 km
# of belts of satellites = 2 (also made up)

Total # of satellite slots @ geostationary orbit = (7400*2/45)*(263,900/45)*2 = 3.86MM.

I'm sure there are more limitations--like it is too expensive to keep satellites in a precise orbit, so most wobble in altitude and latitude. Also, if 70% of the earth is water, you have a lot of coverage where you don't need it. The point is, we can fit a lot more.