Iodine-powered spacecraft completes in-orbit test for the first time
An engineering study published on the 18th in the British journal Nature pointed out that the use of iodine in electric propulsion systems instead of xenon, which is more expensive and difficult to store, may improve the performance of spacecraft. The results of the study highlight the advantages of iodine as an alternative propellant for the aerospace industry.
Electric propulsion systems use electricity to convert propellant into thrust. As the current mainstream propellant, xenon is scarce, requires special pressurized equipment for storage, and has high commercial production costs. To ensure the long-term sustainable development of the aerospace industry, it is necessary to find an alternative propellant. A possible alternative is an iodine. Compared with xenon, iodine is less expensive, abundant in production, and can be stored in a solid-state. Iodine exists in a shiny purple-black solid state under standard conditions, but as long as the iodine is heated at a lower pressure, it will directly sublimate from the solid to gas, which makes iodine a perfect high-efficiency fuel for ion thruster engines. Previously, iodine has been able to achieve higher efficiency than xenon in ground tests, but it has not been reported that a spacecraft that uses an iodine-electric propulsion system has completed an in-orbit operation.

This time, a team of scientists from the French company ThrustMe reported that a small satellite using an iodine working fluid propulsion system successfully achieved an in-orbit operation. Its working principle is that the propulsion system first heats the solid iodine to sublime it into a gas, and then turns it into iodide ions and free electrons under the bombardment of high-speed electrons, and then the positively charged iodide ions are accelerated to the exhaust port to be discharged. Promote the target to fly forward.
The propulsion system promotes a 20 kg cube satellite launched in space on November 6, 2020, and its maneuver has been confirmed by satellite tracking data. Studies have shown that iodine is not only a viable propellant, it can also ionize more efficiently than xenon.
The researchers pointed out that this demonstration may accelerate the aerospace industry's acceptance of alternative propellants, and it also shows the potential of iodine in a large number of space missions. For example, iodine can significantly promote the miniaturization and simplification of the system, resulting in small satellites and satellite constellations with new capabilities for deployment, collision avoidance, and disposal.
 

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