Ion thrusters that self-assemble from fuel have promise for small spacecraft

As the trend for miniaturisation of electronic technology continues, more spacecraft and satellites are becoming smaller, with typical sizes reducing from about that of a fridge or small car to approaching a shoebox or even a smartphone. But even these tiny craft need a way to manoeuvre and change their orientation to take measurements or send signals in the appropriate direction. But the types of plasma thrusters used on larger craft do not work well when scaled down. Graduate mechanical engineering student Brandon Jackson is leading development of a method that may be cheaper and more effective than current technologies.

One way of propelling small spacecraft is known as electrospray and involves using electrostatic fields to eject fluids of charged particles from a hollow needle-like device in the opposite direction to the movement required. But needles are expensive to make and delicate. Jackson’s solution, which he is developing with Prof L Brad King, is to use a magnetic liquid salt as a fuel. This has an interesting property; it is a ferrofluid. That is, in a magnetic field, it spontaneously shapes itself into an array of spiky peaks, looking a little like a miniaturised hedgehog. Moreover, when a strong electric field is applied to those peaks, each one emits its own individual jet of ions.