Fire the electrospray thrusters! Tiny module could drive small satellites
A new propulsion system from MIT spinout Accion uses tiny chips and a salt solution to generate enough thrust to jostle satellites in space.
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Small, low-cost satellites are growing in importance for communications, research and exploration. But according to MIT aeronautics and astronautics alum Natalya Brikner in a report just released by MIT, the problem with lots of small satellites is that they have no proper means of propulsion, so they can't control where their cameras point, and, after whizzing around the planet for a few months, they eventually fall into the atmosphere and burn up.
Brikner is co-founder and CEO of MIT spinout Accion Systems, which aims to solve that problem and has developed a device known as MAX-1 -- a tiny electrospray propulsion system.
The device consists of a reservoir tank that holds a liquid salt propellant. Above this sit eight chips, each measuring about 1 centimeter square (about 0.4 square inches) and 2 millimeters (about 0.08 inch) thick. Each chip has a base filled with approximately 500 pointed tips, a configuration that sucks up the propellant below like a cotton pad dipped in a liquid. Above the base is a grid with small holes. When an electrical current is run between the base and the grid, the liquid salt produces charged ions that rocket out of the holes, providing thrust in the opposite direction.
Brikner says the thrust was about enough to move the device around a sheet of paper here on Earth, but without the resistance of air in the vacuum of space, a little propulsion can go a long way.
In fact, when a mini version of the MAX-1 was tested out in a vacuum chamber it was found to produce 100 micronewtons of force per square meter. Unless you're a rocket scientist, that might not mean much, but it's helpful to know that such a force is, according to the report, "enough to stabilize a CubeSat launched from the International Space Station, and to compensate for atmospheric drag."
CubeSats are tiny box-shaped satellites that are about "4 inches long, have a volume of about 1 quart and weigh about 3 pounds," according to NASA. They're used for research and potentially "low-cost technology development."
The MAX-1 modules are set to begin production in July and should be shipped to customers by the end of 2015. Till then, check out this video of the thrusters rotating a magnetically levitated CubeSat in a vacuum chamber.