Bryce Vickmark/MIT

Remember that Lego spaceship you once built? What if it could have a working thruster the size and weight of a Lego brick?

MIT professor Paulo Lozano is designing prototype "microthrusters" that would propel pint-size satellites in orbit and into deep space.

The director of MIT's Space Propulsion Laboratory believes such microthrusters and the scaled-down satellites they would power could radically reduce the cost of space missions compared with conventional spacecraft technology.

So-called CubeSat satellites are roughly the size of a Rubik's Cube. Dozens of CubeSats have been put into orbit over the past decade, often as part of university research projects.

But instead of letting them burn up in Earth's atmosphere as their orbits decay, Lozano wants to equip them with tiny thrusters to prolong their usefulness -- and give them new functionality.

The Lego brick-size microthrusters would be installed on CubeSats to propel them in various directions. When a voltage is applied, a liquid propellant in the microthruster emits a stream of ions through tiny nozzles. The charged particles propel the satellite forward.

Four thrusters in this solar-powered ion electrospray propulsion system (iEPS) could provide attitude control and main propulsion for standard "1U" CubeSats, which measure about 4 inches to a side and weigh 2.2 pounds.

"Less than 150 g of propellant would be required by a 1U CubeSat to reach Earth's escape velocity from [low Earth orbit] and explore interplanetary space," the lab says on its Web page.

It might be possible to send a fleet of CubeSats to explore the moons of Jupiter, for instance, for the same price as sending a large spacecraft.

"And you could do as exciting science as you could with the big ones, like go to Europa," Lozano said in a release. "Why not? The sky is the limit."

Other possible missions include clearing the massive pile of orbital debris floating around the Earth, de-orbiting satellites at the end of their service lives, and correcting atmospheric drag in low Earth orbit.

Other researchers are also working on microthrust technology for small satellites. Scientists in Switzerland, for instance, say they can send a shoebox-size satellite to the moon in six months with only a few drops of fuel.

"The goal is to make [CubeSats] do most of the things we already do with big satellites, except in a less expensive way," Lozano added. "People have very big plans for these very small spacecraft."