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Many of our satellites, probes and other orbiting instruments use one form or another of electric ion drive propulsion. The vast majority tend to use the noble gas Xenon, which is electrically charged or ionized and expelled from the craft. Thanks to Newtonian physics when the ionized gas molecules are expelled they exert an equal and opposite force on the craft creating: thrust, which can be vectored and controlled to maneuver an object in space. But there’s a problem: Xenon is rare, therefore Xenon is expensive, and satellite manufacturers have to compete with several terrestrial uses of the gas such as sunbeds and bactericidal lamps. It is mostly obtained commercially by extraction from liquid air which is labor-intensive, as the atmosphere only contains 0.086 parts per million of Xenon by volume. An alternative is needed.
That’s where French aerospace company ‘ThrustMe’ (Nope Not Kidding) found the inspiration to pursue a better method for ion propulsion. Using Iodine in place of Xenon.
A Revolution In Alternative Ion Propellant
As CNET observed, “Iodine is incredibly prevalent, inexpensive and easy to store with minimal effort. Seaweed, printing ink, dairy, and even table salt are rich in the non-reactive element.”
In a statement, ThrustMe CTO and Co-Founder Dmytro Rafalskyi said,
“ThrustMe is pioneering the use of iodine within the space industry”
“Iodine is significantly more abundant and cheaper than xenon, and has the added advantage that it can be stored unpressurized as a solid”. Xenon by comparison must be stored under high-pressure (typically 100-200x atmospheric pressure). Iodine also has a storage density almost 3x higher than xenon (and 9x higher than krypton). This enables significant simplification and miniaturization of propulsion systems.
“ThrustMe has developed a revolutionary propulsion system with an iodine ion thruster, the NPT30-I2, which includes all needed subsystems and fits within a single package of roughly 10 cm x 10 cm x 10 cm” says Dmytro. Comparison with xenon shows that iodine gives an almost 50% performance enhancement.”
While SpaceX and other competitors are investigating alternate materials such as krypton which has a higher ionization threshold and lower atomic mass as utilized in the StarLink Satellites, iodine could be game-changing due to its ready availability. With more research and development the viability of this alternative fuel can be determined, but ThrustMe’s successful test using a mini-satellite which has been described in a peer-reviewed study is a great indication.
https://www.youtube.com/watch?v=HpQSc3AHWqw
