Until now, rockets and spacecraft have mainly been powered by chemical engines. But now, researchers are starting to test new electric motors called ion thrusters. Among these ion thrusters, there is one that recently passed an in-orbit test. It is an iodine propellant. According to engineers, this step could lead to the possibility of using smaller, less expensive, but above all more efficient engines on future satellites and spacecraft.
Regarding the operation of ionic motors, an electric field is created and it will be used to accelerate charged ions which will be propelled. Obviously, this system does not generate as much thrust as a conventional chemical engine, and it is not possible to use it to launch a spacecraft from the surface of the Earth. However, electric thrusters are highly efficient at producing thrust considering the less amount of fuel they carry. They are thus very practical when the spacecraft is already in space.
Currently, the most widely used fuel in electric thrusters is xenon. It is, however, a very rare and also very expensive item. Its price is around $ 3,000 per kilogram. In addition, its use requires the use of large tanks and very complex plumbing. This is where iodine comes in, which has a lot of advantages over xenon.
The characteristics of iodine
Over the past 20 years, researchers have investigated the possibility of using iodine instead of xenon. This substance is much cheaper and more abundant than xenon, and it can be stored in solid form in a place that is not pressurized. Previous studies have already shown that electric iodine thrusters were more efficient than those using xenon.
However, iodine is not perfect since it has some disadvantages. It is a very corrosive substance, which can cause problems with the electrical circuits and systems on board the spacecraft. In addition, it is possible that the vibrations during takeoff will break up the solid iodine and the debris could damage the propulsion system.
The test results
Despite the negative points regarding the use of iodine, scientists today have successfully launched an electric iodine propellant into space. They were able to demonstrate that the system could propel a machine into orbit.
The propellant in question is called NPT30-12, and it was developed by the company ThrustMe. The system is contained in a volume of 10cm * 10cm * 10cm, and its mass is about 1.2 kg. It was used to propel a 20 kg cubesat called Beihangkongshi-1, operated by the Chinese company Spacety.
Based on radar data obtained from the ground, the researchers were able to confirm that the thruster helped the satellite to maneuver in orbit. In all, the electric thruster was able to increase the altitude of the satellite by about 3 km.
According to the researchers, these results show that iodine is a viable solution for electric propulsion. It is also 50% more efficient than xenon in terms of propulsion. Indeed, it is easier to electrify iodine than xenon. To cope with the disadvantages of using iodine, scientists have found solutions such as the development of ceramics and polymers to protect metal components from corrosion.
In the coming years, the majority of spacecraft will be equipped with electric thrusters. Based on these results, iodine thrusters will surely be among the thrusters chosen by satellite and spacecraft builders.