A team at NASA is testing a chemical-free propulsion system that will use Earth's magnetic field to move satellites and spacecraft in orbit.

Space tethers collect current when they fly near the ionosphere-the charged, upper layer of atmosphere-and magnetic field. The current flowing through the wire will be pushed on by Earth's magnetic field, creating a force that can be used to raise or lower a spacecraft's orbit.

Currently, satellites in Earth's orbits have to periodically re-boost themselves owing to constant degradation of their orbits due to friction from colliding with atmospheric particles. The satellites have a limited supply of fuel for thruster rockets. When the gas runs out, the spacecraft's days are numbered.

A tether could lower a satellite's orbit so that it could, for example, more quickly re-enter Earth's atmosphere at the end of its operational life and avoid becoming another piece of space debris.

"We want to demonstrate a tether propulsion system that someone can just go and copy it, and fly it," Discovery News quoted Les Johnson at NASA, as saying.

"We really are interested in casting a wide net. We're not going to specify the precise technology to be demonstrated," NASA's chief technology guru Bobby Braun said. (ANI)