Taking into account factors such as safety and propulsion efficiency, people are gradually turning their attention to a "bulky" element in noble gases - xenon (Xe). As an inert gas, xenon with atomic number 54 is located in the lower right corner of the periodic table, which is chemically inactive and does not easily react with other substances, so it will not affect electronic devices, sensors, etc. Among various inert gases, xenon has a large atomic number and is relatively easy to ionize in noble gases. As a result, xenon has become the most widely used fuel in ion thrusters, and xenon ion engines can be seen in many satellites and space probes.
Xenon substitution
However, xenon reserves are scarce and naturally very expensive. Decades ago, it was not very prominent among the huge expenses of space launch, but with the rapid development of space science and technology and the continuous reduction of launch costs in recent years, finding propellants that are more economical than xenon and even achieve higher impulse has become a rigid need.
An alternative element that is easier to think of is the noble gas krypton (Kr), which is only one cycle smaller than xenon. Although this is a "second best" choice, the content of krypton in the air is ten times that of xenon, and the preparation price is only one-sixth of the latter, so many research institutions at home and abroad have conducted a lot of experimental research on the use of krypton as a propellant in ion engines. Since 2018, krypton has been favored for commercial satellite applications. For example, in Musk's Starlink project, the Hall thrusters used by satellites are fueled by krypton.
Taking into account factors such as safety and propulsion efficiency, people are gradually turning their attention to a "bulky" element in noble gases - xenon (Xe). As an inert gas, xenon with atomic number 54 is located in the lower right corner of the periodic table, which is chemically inactive and does not easily react with other substances, so it will not affect electronic devices, sensors, etc. Among various inert gases, xenon has a large atomic number and is relatively easy to ionize in noble gases. As a result, xenon has become the most widely used fuel in ion thrusters, and xenon ion engines can be seen in many satellites and space probes.
Xenon substitution
However, xenon reserves are scarce and naturally very expensive. Decades ago, it was not very prominent among the huge expenses of space launch, but with the rapid development of space science and technology and the continuous reduction of launch costs in recent years, finding propellants that are more economical than xenon and even achieve higher impulse has become a rigid need.
An alternative element that is easier to think of is the noble gas krypton (Kr), which is only one cycle smaller than xenon. Although this is a "second best" choice, the content of krypton in the air is ten times that of xenon, and the preparation price is only one-sixth of the latter, so many research institutions at home and abroad have conducted a lot of experimental research on the use of krypton as a propellant in ion engines. Since 2018, krypton has been favored for commercial satellite applications. For example, in Musk's Starlink project, the Hall thrusters used by satellites are fueled by krypton.
