There are lots of tiny little satellites orbiting the earth above your head right now. But that’s all they do: orbit, around and around. There is a plan, however, to give these cheap, so-called CubeSats the ability to strike out on their own. With the aid of some relatively simple propulsion technology, the goal is to push these tiny satellites beyond earths’s gravitational pull and into the outer reaches of space.
The idea is that, in the not so distant future, unmanned space exploration will be accessible to everyone, and not just the NASAs of the world – like tiny little drones in space.
Key to all this is little more than water. Using an electrolysis propulsion system, researchers from Cornell University have been working since 2009 on a system that splits water into hydrogen and oxygen gas that can then be ignited to create thrust. The plan is to launch two of these water-propelled CubeSats into space, and send them orbiting around the moon. Another CubeSat propulsion project is being conducted at the University of Michigan, and raised money through a successful crowdfunding campaign.
“It kind of levels the playing field for a lot of science inquiry. Not everybody is capable of running a billion dollar spacecraft mission for NASA,” explained Mason Peck, former chief technology officer for NASA, who is now working with fellow researcher Rodrigo A. Zeledon at Cornell on the electrolysis propulsion system. “This actually democratizes access to space.”
Unlike, say, a communications or military satellite, CubeSats are practically microscopic by comparison – mere 10cm cubes, according to the specification first defined in 1999, that have a volume of just 1 liter and can weigh no more than 1.33 kilograms. But, surprisingly, it’s not size that’s held CubeSat propulsion efforts back.
It's not the CubeSat's small size--10cm--that has held propulsion efforts back.
“It’s primarily the fact that CuebSats are secondary payload,” Peck explained. “They’re hitching a ride on some other space craft, and that other space craft does not want the little CubeSat to destroy its expensive payload. So for that reason, the CubeSat specification that allows you to launch these as secondary payloads, prohibits you from using material under pressure, or material that’s explosive, or material that’s volatile, in the sense that if it leaks out it would evaporate and poke the surfaces of the spacecraft.”
But water, explains Peck, is not only non-volatile, it’s “pretty much the ultimate green propellant.” It sits in a tank, gets zapped by an electrolyzer, which separates the hydrogen and oxygen, and is then sent to a combustion chamber until enough pressure builds up to ignite the whole thing. Safe and simple! In theory.