Helium – the lightest gas in the world, seemingly harmless, but a cause of many delays in important space missions. But why is helium favored for use, and what makes it a challenge for the space industry?
Helium is a chemically inert element that does not react with other substances and is also not easily flammable, making it safe in the harsh environment of space. With an atomic number of 2, helium is the second lightest element after hydrogen. Its light and inert properties are the main reasons it is a top choice for use in rocket systems and spacecraft.
Another important factor is helium’s extremely low boiling point (-268.9°C), which allows it to remain in a gaseous state even in super-cold environments where many types of rocket fuel are stored. This feature ensures that helium can operate stably in harsh conditions without liquefying or losing its critical properties.
Helium is used in rocket cooling systems. (Photo: According to NASA).
Helium is primarily used to pressurize fuel tanks, helping maintain the flow of fuel to the engine without interruption. When fuel and oxidizer are burned in the engine, the empty space in the fuel tanks needs to be filled with helium to maintain pressure. Since it does not interact with residual fuel, helium helps avoid unwanted reactions.
Additionally, helium is also used in rocket cooling systems. With its ability to withstand super-low temperatures without losing its properties, helium helps preserve fuel and rocket components under optimal conditions.
Due to its small atomic size and low molecular weight, helium easily escapes through small gaps or seals in storage systems and fuel systems. This makes helium control a significant challenge. Space engineers often encounter helium leakage issues, which can delay or even cancel space missions.
A notable example is the incident with the Boeing Starliner spacecraft, where a helium leak was detected just before the mission was set to launch. Sensors detected the leak in one of Starliner’s components, forcing NASA to postpone the mission for inspection and risk assessment. In space, leakage errors can lead to critical decisions, such as returning the craft to Earth without completing the objectives.
Some space missions have experimented with using other gases like argon and nitrogen, as they are also inert gases and can sometimes be cheaper. However, helium remains the preferred choice due to its superior features and proven effectiveness.
A new solution has been implemented on the European Ariane 6 rocket, replacing helium with a pressure generation system that converts a portion of the main fuel into gas. However, this system encountered issues during its test launch, raising challenges regarding pressure generation in the rocket industry.
These helium leakage incidents highlight the urgent need to improve valve designs and tightening mechanisms. The space industry faces numerous challenges in finding new solutions to ensure that space missions run smoothly and safely, but helium remains an indispensable component for the time being.
The use of helium in rockets and spacecraft continues to be a crucial factor in ensuring the success of future space missions.
