How elliptical is geosynchronous orbit?

Question

I ask this because I have been curious what problems might arise when designing a space elevator. If you have a counter-weight in geosynchronous orbit with a ultra-strong/ultra-light cable hanging from it down to Earth's surface, we would need quite a bit of cable in reserve to account for the elliptical orbit of the counter-weight, right?

If you could figure out approximately the difference between the major and minor axes, that would satisfy my curiosity. Or if you could point me in the right direction, I could scrounge for my old physics notes with orbit equations.

Good article about space elevator:
http://www.spectrum.ieee.org/aug05/...

Another question of mine about probable space elevator issues:
http://answers.yahoo.com/question/index;_ylt=Anpg1h1Yb3bdMCN_tXqR6gjsy6IX?qid=20060705144411AAKDTk0

edit: Oops, yah the counterweight would be beyond the geosynchronous orbit, but the center of mass of the entire elevator (weight + cable) would be in geosynch orbit.

Bad link given before:
http://www.spectrum.ieee.org/aug05/1690

Answer 1

A geosynchronous orbit can be highly elliptical, because the only requirement is that it have a period of 24 hours.

But a space elevator requires a GEOSTATIONARY orbit, which must be circular, and have zero tilt with respect to the equator.

Answer 2

A geosynchronous orbit is any orbit that has a period of 24 Hrs. It can be ellyptical and inclined. More or less it would look from an earth observer as if the satellite was movin in a figure of 8.

A geostationary orbit is a circular geosynchronous that its orbital plane cuts the earth on the equator(inclination equals to 0). Geostationary satellites stay on the same point in the sky relative to an earth observer 24hrs a day. Their orbital height is around 36000km.

Answer 3

Geosynchronous orbits are basically circular; they adjust the orbit to keep such satellites in a perfect postion, so you don't have to go outside and fiddle with your Dish Network or DirecTV dish all the times.

If the orbits were ellipitical, they would not stay put over the Southern Horizon--think eggshaped orbit for ellipitical and you'll easily see what I mean.

These orbits are very special in that they must make 1 revolution around the planet in 24 hours so they appear stationary in the sky to us. To accomplish this, the orbit must be at the equator and on the order of 23,000 miles high.

And to those that don't think they move, yes they do, but not from your frame of reference here on earth!

Answer 4

It seems to me that geo-syncronous orbit must be circular, as the satellite would remain fixed in the sky.

In the case of a space elevator, I read about that also. The counterweight would actually extend just beyond a syncronous orbit distance, thereby keeping the rope (or ribbon, which is where they are currently leaning) taught, like swinging a rock on a rope around your head.

Answer 5

What kind of geosynchronous orbit? There is elliptical geosynchronous orbit and circular geosynchronous orbit and I think active geosynchronous orbit or something like that. Each is different, and only one of them would have an elliptical shape to it, unless the controller of the active orbit controls the orbit into an elliptical shape.

Answer 6

It isn't elliptical at all. Any departure from a perfect circle would cause the satellite to speed up and slow down in orbit, so geosynchronous satellites are maintained in orbits that are perfectly circular.

Answer 7

I agree with 2nd answer. The orbit of that setellite couldn't be eliptic. For to get a constant speed setellite have to keep circular orbit. When distance multiplie by two then gravity multiplie by 4!! Don't forget this.

Answer 8

if it's geosynchronous, it doesn't have an orbit because it doesn't move.

For what you want to do, you are thinking to 20th century... think more of an extremely thin and light glass fiber cable the 'elevator' could follow up using it's anti-gravity-drive for propulsion.

Answer 9

A lot of excellant answers here. Yes they are circular at about 23,000 miles out. They do move, but with us. An elipse would cause a speed variation contrary to staying put.