ThrustMe’s new sexy iodine electric propulsion system could transform space travel

Electric iodine thruster firing in a vacuum chamber. (Image credit: ThrustMe)
Existing satellites orbiting the Earth typically use electric ion motors for propulsion. There are different types of ionic motors, but the most common type relies on ionized xenon gas which is driven from the craft by natural forces. Thanks to Newton’s third law of motion, the force of gas expelling exerts an equal force in the opposite direction, which pushes the spacecraft in a particular direction. They are not useful on earth or in the atmosphere, but their high efficiency makes them excellent for space travel, where there is no atmosphere and minimal gravity to contend with.

The use of xenon gas is expensive and however poses many problems. It would be much more economical and practical if we could use a more common ionizing fuel, such as iodine for example. And it turns out that’s exactly what French space technology company ThrustMe designed, developed, deployed and tested. One of the most important aspects engineers must consider when designing spacecraft, even unmanned, is mass. An increase in mass means an increase in the required launch thrust far greater than the increase in mass itself. The use of noble gases like xenon and krypton requires bulky high pressure storage tanks which are dangerous when filled and require their own support structures. Even full, these reservoirs still do not represent an excellent energy density.

In contrast, use iodine – which is solid at room temperature; medical iodine is in solution – allows designers to avoid all of this extra complexity and mess. According to ThrustMe, it also carries around three times the storage density. These two advantages alone would be enough to justify the change, but iodine is also abundant in nature and much cheaper than the rare rare gases normally used for such propellants.

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ThrustMe also says that iodine is more efficient: “almost 50%” more efficient ionization, in fact. Despite this, it is not without flaws. Apparently, the company’s current iodine-based engines are not as “responsive” as xenon engines. ThrustMe also admits that corrosive iodine requires ceramic containment to prevent corrosion of sensitive structures in spacecraft. Yet these successful tests represent a solid step forward for convenient and affordable space travel.

The concept of using iodine as a fuel for electric motors is not new, and previous testing has shown promise, but ThrustMe has actually tested its motor (known as NPT30-I2) in it. ‘space. A small 20 kilogram CubeSat satellite launched late last year by Chinese company Spacety has been successfully handled and moved by ThrustMe’s iodine thruster. The test results ultimately underwent “rigorous” peer review and are now published in the scientific journal Nature. You can find the paper here.

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