Is it possible to tether a satellite in geosyncronous orbit to a fixed point on earth ?

Question

If it is possible, can you think of a practical use for such a set up ?

Answer 1

Yes. It's been possible for years. There are plenty of geosynchronous satellites up there, and the first one was 43 years ago. There's no requirement for a tether. Satellite television is one practical use to which this type of satellite has already been put.

Additional: -

Sorry, I think I misconstrued your question. Intermittently through the years there has been talk of space elevators which could in theory be built by using a geosynchronous tether, but would require the sort of intensive research and development which NASA put into the Apollo programme. As you can imagine, many people might have problems with billions or trillions of dollars being invested in this type of research, so the likelihood is that it will never happen unless circumstances dictate that it becomes necessary. It would negate the necessity of building huge wasteful rockets / shuttles to transport astronauts and supplies into orbit though.

Answer 2

Not really. The earth vibrates. expands, and contracts, in terms of miles each way. The first time the tether was stretched, the satellite would be pulled (eventually) into the Earth. Any tether would have to be extremely elastic, to the point that all tension would be absorbed by the belt, and absolutely none was transfered to the connected satellite. Not likely, even with the most fanciful of materials.

More possible to have an artificial orbit, supported by rocket boosters and other controls, that would counteract the decay of the orbit caused by the tether and maintain a constant distance from the connection point on Earth. But this wouldn't be a geosynchronous orbit, it would be a flightpath.

Answer 3

Theoretically, yes.

Physically, no!

Geostationary satellites are 22,236 miles above the Earth's surface. There's no material strong enough to make a tether that long. The tether won't be strong enough to support its own weight.

A geosynchronous satellite wouldn't be enough. Geosynchronous satellites are satellites whose orbital period matchs the time it takes for the Earth to rotate. If the orbit were at any kind of angle relative to the equator, the satellite would appear to trace out a figure 8 in the sky. That kind of movement would put more stress on the cable, in addition to the stress of the cable's weight. The satellite has to be exactly, precisely, at a 0 degree inclination relative to the equator in order to be geostationary - an orbit where the satellite would be stationary relative to a location on Earth.

There are no truly geostationary satellites, since the Sun, the Moon, deformities in the Earth's shape, and sunlight will all perturb the satellite's orbit. A XIPS thruster firing nearly constantly could compensate for the perturbations extremely quickly maintaining a nearly stationary point relative to the Earth's surface, but it wouldn't be perfect. Any movement at all relative to the Earth will put stress on the cable, in addition to the stress already on the cable from its own weight.

Answer 4

The idea is being worked on to use the tether as an elevator to space. The mass of the object at the end keeps the tether tight, kind of like swinging a ball on a string around your head. I believe electromagnets were used as the propulsion for the elevator itself. As to whether or not it is possible, I've read they are still working on a material for the tether that is strong enough and light enough for the application.

Answer 5

You're talking about physical tether, aren't you? I don't think there are any man made materials strong enough to withstand the sheer force let alone weight of the tether from ground to orbit.

I know virtually nothing about heat shields or shielding, but what about that section of the atmosphere that the space shuttle goes through when reentering? I know it gets really hot. Would a tether in a constant spot be able to withstand the the heat?

The only practical use I could see is to exhaust gases or waste material into space. Or maybe some sort of permanant transport to the International Space Station.

Answer 6

Geosynchronous satellites are common. However, they are not "tethered" in the sense that they're physically fastened to the surface by some means. The easiest way to place a satellite in geosynchronous orbit is to place it far enough from Earth so that its orbital velocity matches the speed of Earth's rotation, thus maintaining its position over a particular location.

Answer 7

Why would you want to do that? The one practical application I would think of would maybe to tether with a fiber optic link. With satellites, there is delay in the signal, for the time it takes the signal to get up to the satellite from the earth station and then back down to the receivers. If you tethered it with fiber optic link for the uplink transmission, you could, theoretically, reduce the signal delay. But, its a somewhat impractical idea.

Answer 8

I think most of the folks missed the point of the practical use...

In the not so distant future this may happen... We have to build longer nano tubes (hundreds of miles)... They have to support not only their own weight but the weight of the payload they will carry into space... The nano tubes could be used to carry/retreve experiments in space, change batteries, etc... These supplies could extend the life of the satellite...

Answer 9

It is not possible (yet) to have any substance strong enough (over the length from the earth's surface to the satellite) to support its own weight

Answer 10

It's possible.

That's actually the whole concept behind the theoretical development of a "space elevator" to a space station or similar device or vehicle in orbit