Scientists have developed an efficient propulsion system for microspacecraft.

As satellites become smaller, scientists need more compact propulsion systems to guide microspacecraft through space. Ming-Hsun Wu, at National Cheng Kung University, Tainan, Taiwan, and Richard Yetter, at Pennsylvania State University, University Park, US, have made small propulsion devices called microthrusters that are ignited using electric energy.

Microthrusters ignited with electric energy could be used to maintain satellites in their orbits

Usually microthrusters are ignited by raising the temperature of the propellant using heating elements until it catches fire. But heat energy can be lost from the system, making it inefficient. This is particularly significant on the microscale because of the large surface-to-volume ratios.

Instead, Wu and Yetter put electric energy directly into the liquid propellant, causing it to decompose and ignite at room temperature.

'This is the first time that electrolysis has been used as an ignition mechanism for a microscale liquid monopropellant microthruster,' explains Wu, 'and the results turned out to be pretty exciting.'

Frederick Dryer, an expert on combustion science from Princeton University, US, is impressed by the results. 'This is truly an excellent demonstration of novel thinking and attention to detail. It is a real step forward in fabrication processes, use of novel fuel formulation, and ignition technologies for micropropulsion applications. In my opinion, the paper represents a seminal work in the micropropulsion field,' he enthuses.

While the current microthruster can be fired only once, Wu and Yetter plan to develop a microthruster that can be fired multiple times. Wu says the microthrusters could be used on microsatellites for maintaining spacecraft in assigned orbits and controlling their orientation.

Ruth Doherty

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