Thrusters no bigger than a penny could soon be moving satellites around, thanks to MIT engineers.
They've invented a device looking rather like a computer chip, and covered with 500 microscopic tips. When stimulated with voltage, these emit tiny beams of ions that, in space, can help propel a shoebox-sized satellite forward.
There are already more than two dozen small satellites, called CubeSats, orbiting Earth, each slightly bigger than a Rubik's cube and weighing less than three pounds.
They're cheap to assemble, and can be launched into space relatively easily - but they lack propulsion systems, and once in space, are usually left to passively spin in orbits close to Earth. After a while, the satellites burn up in the lower atmosphere.
In future, though, more CubeSats could be launched farther from Earth, creating space debris.
"These satellites could stay in space forever as trash," says associate professor Paolo Lozano. "This trash could collide with other satellites. You could basically stop the Space Age with just a handful of collisions."
Microthrusters could prevent this problem. CubeSats could propel down to lower orbits to burn up, or even act as garbage collectors.
"Normally, propulsion systems have significant infrastructure associated with propellant feed lines, valves [and] complex power conditioning systems," says Timothy Graves, manager of electric propulsion and plasma science at Aerospace Corp.
"Additionally, the postage-stamp size of this thruster makes it easy to implement in comparison to other, larger propulsion systems."
The researchers envision a small satellite with several microthrusters, possibly oriented in different directions. When the satellite needs to propel out of orbit, onboard solar panels would temporarily activate the thrusters.
In the future, Lozano predicts, microthrusters may even be used to power much larger satellites: flat panels lined with multiple thrusters could propel a satellite through space, switching directions much like a rudder.