Micro-thrust engines no larger than a penny could move future small satellites in space, researchers at the Massachusetts Institute of Technology say.

The engine has none of the valves, pipes and heavy propellant tanks of typical bulky satellite engines, they said.

Instead the design, developed my MIT aeronautics and astronautics Professor Paulo Lozano, is a flat, compact square, looking something like a computer chip, with microscopic tips that when stimulated with voltage emit tiny beams of ions when an electrical voltage is applied, the university reported Friday.

The stream of charged particles emitted by the device could propel a small satellite through space, Lozano said.

The researchers found an array of 500 tips produces 50 micronewtons of force, which on Earth could only support a small shred of paper but which in the zero gravity of space would be enough to move a 2-pound satellite.

"They're so small that you can put several [thrusters] on a vehicle," Lozano said.

A small satellite equipped with several micro-thrusters could "not only move to change its orbit, but do other interesting things -- like turn and roll," he said.

With micro-thrusters and onboard solar panels to create voltage such a satellite could easily make changes in its position or orbit, the researchers said.