A group of researchers have discovered factors that make it difficult to make an electric motor more important in the near future. Interestingly, component is not a rare earth mineral, but is a common iodine supplement. A small satellite was launched into orbit last year with iodine as a propellants, according to an article in The Nature today.
Traditionally, chemicals have been used as propellants for the spacecraft. According to the European Space Agency, electric-propulsion, the electric motor used to accelerate the propellant is a more efficient way of propulsion, as it uses lesser mass of propellant & can eject it up to 20 times faster. This can dramatically reduce the mass of propellant spacecraft carry-for-orbit for such tricks and tactics, further reducing the cost of launching price these spacecraft.
This method of motion is especially used for satellites used for applications such as Earth observation, navigation & telecommunications. However, the current propellant of choice is Xenon, an inert gas found in trace amounts on Earth. Sometimes, krypton has also used.
Michael Tate, co-founder and COO of Infinite Composites, a company specializing in the manufacture of pressure vessels to contain propellants, said: “Krypton and xenon have a very high density. Their pressure typically ranges from 3000 psi (200 bar)-5000 psi (350 bar) which is ideal for electric propulsion systems because it is about “throwing” as much mass behind you as possible.
However, commercial production of the propellant is not only rare, it is also expensive and unsustainable in the long term. A collaborative research team made up of French space company ThrustMe and technical experts from Nanyang Technological University in Singapore used iodine instead. .
According to the ThrustMe website, iodine can be stored in the spacecraft as a solid fuel, unlike xenon, which must be pressurized; at a moderate temperature, the halogen element sublimes, converted into its gaseous form, and skips the liquid phase entirely. makes it ideal for applications where pressurized gases are required.
On November 6, 2020, ThrustMe used iodine as a propellant in a 20kg CubeSat and maneuvered it into orbit. Nature’s article not only confirms the use of iodine as a propellant, but also claims that it has higher ionization efficiency.
“Ionization efficiency refers to the efficiency with which energy can be used to ionize the propellants into plasma that is eventually ejected from the spacecraft,” said Dr. Natalya Bailey, co-founder of Accion Systems, that electric propulsion systems for satellites using proprietary ion electrospray thrusters.
István Lörincz, President and Co-Founder of Morpheus Space, which offers artificial intelligence powered satellite propulsion systems, adds: “The higher this efficiency, the less propulsion and electrical energy is needed to operate the propulsion systems, which results in smaller tanks. Solar panels and batteries resulting in cheaper satellites and rocket launches.
This is also the assertion of the authors in the work that the use of iodine as a propellant can make satellite systems smaller, simpler, easier to deploy, and to dispose off after their life-time. Iodine is much cheaper to manufacture and more common than xenon on Earth. However, there are also some drawbacks.
As Dr. Bailey notes, “Fuels like iodine require heating before use, which results in heating and cooling periods. On a larger level, electrical propulsion systems are power intensive, keeping them from powering the satellites and using their primary energy payloads at the same time, resulting in significant downtime during which the satellites cannot complete their intended mission.