Now, to make CubeSats more maneuverable, a team from Purdue University has developed a system that would allow the mini satellites to safely propel themselves by spraying jets of ordinary water.
The Purdue prototype was a CubeSat measuring 10 cm3 (0.6 in3) and weighing 2.8 kg (6 lb), loaded with off-the-shelf electronic components normally used for Internet of Things devices. There's a computer that wirelessly receives instructions and relays them to an inertial measurement unit that works out how to act on them. But the star of the show was the propulsion system, dubbed a Film-Evaporation MEMS Tunable Array (FEMTA) thruster.
Four of these FEMTA thrusters were built into the prototype, each one carrying about a teaspoon of ultra-purified water. The tank is full of capillaries about 10 microns wide, which is too small for the water to flow out thanks to its surface tension. To control when it escapes, small heaters around the edges of these holes can be activated on demand, warming the water into vapor and creating tiny blasts that turn the craft.