Nanosatellites are smartphone-sized spacecraft that can perform simple, yet valuable, space missions. Dozens of these little vehicles are now tirelessly orbiting the earth performing valuable functions for NASA, the Department of Defense and even private companies.
Nanosatellites borrow many of their components from terrestrial gadgets: miniaturized cameras, wireless radios and GPS receivers that have been perfected for hand-held devices are also perfect for spacecraft. However, according to Michigan Technological University’s L. Brad King, there is at least one technology need that is unique to space: “Even the best smartphones don’t have miniaturized rocket engines, so we need to develop them from scratch.”
Miniature rockets aren’t needed to launch a nanosatellite from Earth. The small vehicles can hitchhike with a regular rocket that is going that way anyway. But because they are hitchhikers, these nanosats don’t always get dropped off in their preferred location. Once in space, a nanosatellite might need some type of propulsion to move it from its drop-off point into its desired orbit. This is where the micro rocket engine comes in.
For the last few years, researchers around the world have been trying to build such rockets using microscopic hollow needles to electrically spray thin jets of fluid, which push the spacecraft in the opposite direction. The fluid propellant is a special chemical known as an ionic liquid. A single thruster needle is finer than a human hair, less than one millimeter long and produces a thrust force equivalent to the weight of a few grains of sand. A few hundred of these needles fit in a postage-stamp-size package and produce enough thrust to maneuver a nanosatellite.
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