can a salellite(geo synchronous orbit) be raised to a geo stationary orbit?

Question

can we develope a technique to put a satellite in geo synchronous low orbit and thereafter raise it to gea stationary orbit thereby cutting cost to fire launch vehicle upto 36000km

Answer 1

First, I think you've got your terms a little wrong. "Geosynchronous" and "geostationary" orbits are both 24-hour orbits, and both have an (average) distance from the earth's surface of about 22,000 miles. A "geostationary" orbit is a special case of a geosynchronous orbit. In a geostationary orbit the orbit is perfectly circular and is directly over the equator. In other kinds of geosynchronous orbits, the orbit is inclined at an angle to the equator and/or is elliptical--but it's still a 24-hour orbit.

It sounds like what you mean is "low earth orbit" rather than "geosynchronous."

Regarding the costs: To put 1kg of mass into geostationary orbit requires a minimum of about 57.8 megajoules of energy (assuming 100% efficient lifting engines). That's true whether you do it in a single step (launching directly into geostationary orbit); or in two steps (launching first into low earth orbit and then later raising it to geostationary). In the two-step method, it takes 31.2 megajoules for the first step, and then only 26.6 megajoules for the second step; but the total is still 57.8.

However, there might be other good reasons (besides just payload energy costs) to do it in two steps rather than one.

Answer 2

Geo synchronous orbit is the same as geo stationary orbit. You mean low earth orbit.

Raising the orbit for an object is like lifting a stone. The higher you lift it the more energy it has. So energy is always required to lift a satellite to a higher orbit. And the main technique to do it is by using rocket fuel.

If you are very patient, and cheap, you might consider using a solarsail to slowly and gradually raise the orbit. You unfold the sail when the satellite is moving away from the sun. And then you fold it up when the satellite swings around earth and faces the sun again. The slight pressure from the solarwind will, in very small increments, boost the satellites energy and raise its orbit. But most communications companies today do not want to wait for their product to begin generating revenue just to save a buck at launch. Instead they would spring for the extra cash needed to ship the satellite to geostationary orbit in one go.

Answer 3

Polar Orbit A polar orbit is a satellite orbit that passes over, or very close to, both poles of the Earth. During a 12-hour day, a satellite in such an orbit can observe all points on the Earth. Geostationary orbit A geostationary orbit is a special case of a geosynchronous orbit. A satellite is in a geostationary orbit when it appears stationary from the point of view of an observer on the Earth's surface. This can only occur when: The orbit is geosynchronous The orbit is a circle The orbit lies in the plane of the Earth's equator Thus, a geosynchronous satellite will be geostationary only with the additional restrictions of it being in a circular orbit situated over the equator. Geosynchronous orbit A geosynchronous orbit may be defined as one with an orbital period (the time needed to orbit once around the Earth) that matches the rotation rate of the Earth. This is a sidereal day, which is 23 hours 56 minutes and 4 seconds in length, and represents the time taken for the Earth to rotate once about its polar axis relative to a distant fixed point. This is about four minutes shorter than the common day length of 24 hours, which is relative to the sun.

Answer 4

1. After a few thousand km into the air, gravity is much reduced and 36000km and 18000km costs won't be that different.

2. I'm pretty sure that's not easily achieved. The principle of geo-stationary orbit is to have the orbit speed equal to the orbit speed of the earth AND produce a centripetal force EXACTLY the same as gravity at that height. I'm pretty sure there's not a second height that this is possible.

Answer 5

You mean raise it from low Earth orbit to geo stationary/synchronous altitude. If you can figure out a way to do that cheaply, and you patent it, and you successfully defend the patent in court, you can get rich.