A new generation of minuscule sensors may one day explore alien planets.

Called "smart dust", they can be carried on the wind like dust particles, and are smart enough to communicate, fly in formation and take scientific measurements, while swirling across the landscape by subtly altering their shape.

They consist of a computer chip, about a millimeter in dimension, surrounded by a polymer sheath that can be made to wrinkle or smooth out by applying a small voltage. Roughening the surface of the polymer means the drag on the smart dust particle increases and it floats higher in the air; conversely, smoothing out the surface causes the particle to sink. Simulations show that by switching between rough and smooth modes, the smart dust particles can gradually hop towards a target, even in swirling winds.

John Barker, an electronics researcher at the University of Glasgow in the UK decided to investigate whether a cloud of similar smart dust "motes" could navigate across the surface of Mars from one point to another, simply by modifying their shape.

"The concept of using smart dust swarms for planetary exploration has been talked about for some time, but this is the first time anyone has looked at how it could actually be achieved. Computer chips of the size and sophistication needed to make a smart dust particle now exist and we are looking through the range of polymers available to find one that matches our requirements for high deformation using minimal voltages," he said.

In his experiment, 30,000 motes were released on a simulated Martian surface. Each device in the simulation could sense its position and switch between two shapes - smooth or dimpled (rough). While the smooth motes were carried easily on the Martian wind, the rough ones experienced enough drag to cause them to fall back to the surface.

This allowed the motes to navigate by shape-shifting. By programming the virtual motes with a simple set of rules, Barker found that most could be made to follow a predefined course. In his simulations, about 70% were able to successfully navigate a 20-kilometre track.

"Scientific studies could theoretically be carried out on Venus using the technology we have now. However, miniaturization is coming on rapidly. By 2020, we should have chips that have components which are just a few nanometers across, which means our smart particles would behave more like macro-molecules diffusing through an atmosphere rather than dust grains."

The scientists hope the pace of miniaturization will make smaller applications available in coming decades. For example, progress in electronic manufacturing should help miniaturize smart dust while electro-active polymers could be used to change their shape, for a very small amount of power.