I’ve heard a lot lately of space shuttles and space stations going around the earth in a “low earth orbit”. Here they experience friction, slow down, and evetually fall to earth.
Is there such thing as a “high earth orbit” and why don’t we use it?
There is, and we do. Nearly all satellites orbit the Earth much higher than the shuttles and space stations do. Many of them are in geosynchronous orbits above the equator at an altitude of about 22,400 miles, a height at which the satellite maintains a constant postion over the surface of the Earth.
Why don’t we use it? Well, there are the Van Allen radiation belts out there, so it’s not very safe. From a page on the subject at NASA:
Also, it takes much more thrust to reach high earth orbit for the same amount of mass. Since fuel has mass and provides that thrust, there’s a hard limit to how high a give vehicle (such as the space shuttle) can go. I believe that the space station was lowered a bit from it’s original design so the russian supply rockets could reach it.
-lv
About the only satellites in geosynchronous orbit are weather satellites.
Geosynchronous orbit is obtained over the equator; it is 22,400 miles above the earth; and as we allow 2 degrees separation between satellites, there is only room for 180 of them up there.
Communications satellites and the ISS, among other things, are mostly in low-earth orbits ranging from between 200-500 miles above the earth.
Obviously, you don’t have satellite TV. The reason you don’t have to move those little dishes, is because the satellites are in geosynchronous orbit. In fact, ALL communications satellites are in this orbit, for the same reason.
On the other hand, almost no weather satellites are in this type of orbit. I’m curious where you got your information from.
Also the 2 WAAS (gps wide area augmentation sat’s) are in geosync orbit. The main gps sats are not in geosync orbit (something like 12,000 miles which is above low earth orbit).
Wheeeee…going back over what I have read over the past fews days, I became convinced that I must have been delusional when I wrote my last post, and after some further research, I think I have only been able to confuse myself more 
Yes, communications satellites are in geosynchronous orbit, but the orbit I was trying to detail is a special geosynchronous orbit - geostationary. CelesTrak: "Basics of the Geostationary Orbit" explains the difference and verifies some of what I said above so I’m not a total idiot, however, it does seem communications satellites are common in those orbits, although I do remember reading somewhere that they weren’t…still trying to find that though.
No, I don’t have satellite TV, but as I understand it, there usually is a short “blackout” period every day while transmission switches between satellites (along with transmission disruptions caused by weather, which is why I never subscribed), I’m deducing that these type of communications satellites may be in geosynchronous but not geostationary orbit and operate at least in pairs.
Quoted from the webpage included above: “It should now be apparent that only satellites which orbit with a period equal to the earth’s rotational period and with zero eccentricity and inclination can be geostationary satellites. As such, there is only one geostationary orbit” which supports my statement of there being only room for 180 satellites at 2 degrees separation, so I sincerely doubt that such rare, precious space would be given over to our entertainment.
If I find the page that seemed to suggest that communications satellites are ordinarily found in LEO, I’ll post again.
wanders off with head spinning
I’ve been unable to find a source for the 2 degree spacing. That seems a bit excessive, since I calculate that to be about 8,000 miles between satellites. That’s bigger than an Earth diameter! I’m sure with modern guidance and navigation systems, they can pack them in a bit tighter and still allow the safety margins for natural drift.