Attach any mass to a string, spin it round and round, suddenly let go of the string and marvel at the speed at which it flies. Well, this precisely explains the principle behind tether technology, which is being researched upon for cheaper means of launching shuttles into space.
In tether technology, cables, miles long, are stationed in an orbit around the earth. On one end there is a shuttle and on the other end of the tether would be a counter mass. This system picks up spacecraft in low orbits and hurls them into higher orbits or towards other planets.
As discussed previously, using the technologies that we have today, the mass to be carried to space is placed into a low-earth orbit by a rocket. It is then boosted to higher orbits or into space (towards other planets, i.e. destination) by rocket thrusters. Though efficient, this method proves very costly.
One of the methods, which is efficient and is also cost effective, is to use space tethers. When the new satellite or space probe is launched, the spinning tether system captures it and flings it farther from Earth.
Now, the principle used is that of momentum exchange. This means that the momentum of the spinning tether would be employed to boost the satellite or the shuttle. So as the tether boosts the body further into space, it itself comes closer to the earth than it was. So after the tether has boosted bodies for a certain number of times, it falls back to earth.
Now, tethers can also be used to reduce space junk. From the time space exploration has begun the various orbit around earth has been cluttered with debris, which could take years, and in some cases centuries, to fall from orbit. The danger of old satellites and rockets hitting new working satellites is always present. In order to prevent this all-future satellites must be inbuilt with the tether technology.
As of today, the cost of carrying one kilogram of mass into the space is very high and this one of the reasons why the rapid momentum of space exploration, is slowly decelerating. The need of the hour is to come up with technology, which can exponentially decrease the cost of launches into space. The technology of tethers could very well be the answer to that.
The next section is space shuttle.