Propulsion Systems Created for Micro Space Satellites

Paulo Lozano (Massachusetts Institute of Technology)

A research group at Massachusetts Institute of Technology developed propulsion systems for miniature space satellites that can help prevent these research devices becoming harmful space clutter. Aeronautics and astronautics professor Paulo Lozano and colleagues from MIT’s Space Propulsion Lab discussed their work at the recent Joint Propulsion Conference of the American Institute of Aeronautics and Astronautics.

Lozano’s team built an electronic thrusting engine about the size of a penny to fit on CubeSat miniature satellites, also known as nanosatellites. CubeSats have a standardized size and design — 10 centimeters in height, width, and depth, with a weight of 1 kilogram — that fit as secondary  cargo on space launches, and are inexpensive to make. CubeSats are made to spin in low-earth orbit, then burn up in space after completing their missions. The CubeSat Lab at California Polytechnic State University in San Luis Obispo records 23 missions to date from university space science labs worldwide.

CubeSats, however, have no propulsion system of their own. To expand the range of CubeSat missions into higher orbit would mean that they would not likely be drawn back into earth’s gravity, leaving them in orbit as space clutter that could threaten collisions with future satellites of all sizes.

A propulsion system added to a CubeSat, therefore, would enable the device to return to a lower orbit and a normal demise. However, the propulsion system would need to be small enough to fit on a CubeSat and not interfere with its mission.

Lozano’s team designed a microthruster that adds little to a satellite’s overall weight. The device is patterned after a microchip, composed of several layers of porous metal, and a top layer textured with 500 evenly spaced metallic tips. The bottom of the chip contains a small reservoir of an ionic liquid plasma that acts as fuel for the device.

The microthruster uses a form of capillary action that draws the ionic liquid up through the chip to the tops of the metallic tips. The researchers configured a gold-coated plate over the chip, then applied a voltage, generating an electric field between the plate and the 500 thruster tips. In response, tiny beams of ions escape the tips, creating a thrust.

In simulation tests, Lozano’s team found the array of 500 tips produces barely enough thrust on Earth to support a small shred of paper. But in zero-gravity space, this tiny amount of force would be enough to propel a one-kilogram satellite.

Lozano notes the thrusters are small enough that a CubeSat can support more than one of these systems, which means the thrusters could do more than return the CubeSat to a lower orbit, but also turn and roll the craft into a desired position. “Just like solar panels you can aim at the sun,” says Lozano, “you can point the thrusters in any direction you want, and then thrust. That gives you a lot of flexibility.”

The following video tells more about the CubeSat thrusters.

• NASA Awards Contracts for Commercial Human Space Flights
• Space Institute Funds Medical Product Commercialization
• SpaceX Dragon Capsule Docks at Space Station
• Satellite Measures Show Ozone Reducing Soybean Yields
• Nanosatellites Launched in SpaceX Falcon Vehicle

*     *     *