Scientists at MIT have taken the still science fiction-sounding technology of plasma ion rockets, and cleverly reduced the design so that an engine can be fashioned from the simplest components while still putting out enough thrust to nudge a satellite around.
And to demonstrate the genius of their invention, the team has crafted a working ion plasma thruster out of a soft-drinks bottle and a Coke can…seriously.
Ion thrusters work by ionizing a gas to give it an electrical charge, and then using a set of electrodes to fire the resulting gas out of the rear of the engine. They’re a lot simpler than chemical rockets, and can use much safer fuel–but they work on exactly the same principle. It’s Newton’s third law: Every action has an equal and opposite reaction. In this case the ions flying out of the back of the engine act to accelerate the engine in the other direction, and though the gas doesn’t have as much mass as you may imagine the exhaust from a chemical rocket may, the ions move much faster the engine still has a similar “punch.”
The MIT design pushes out ions up to 10 times faster than a chemical rocket, and it’s called a Mini-Helicon. It’s much smaller than similar engines, and has just three main sections. The first is a quartz tube which surrounds the “active” part of the engine, the second is a suite of audio-frequency antennas that excite the “fuel” gas into ions, forming a plasma. And lastly a group of magnets that help form the plasma, contain it, and direct it out of the engine.
The simplicity of this design allowed the “junk” engine to be built with a glass soft-drink bottle standing in for the quartz tube, and a coke can for the RF antenna. Though it was technically a laboratory prank, it demonstrates the low-cost potential for ion thrusters, which also use cheap fuel–the mini-helicon is the first to use cheap and ubiquitous nitrogen, for example–as an excellent way to steer satellites around in orbit.