What is Helium?

About Helium:

• It is an inert gas and does not react with other substances or combust.
• Its atomic number is 2, making it the second lightest element after hydrogen.
• Helium also has a very low boiling point (-268.9° C), allowing it to remain a gas even in super-cold environments.
• The gas is non-toxic, but cannot be breathed on its own, because it displaces the oxygen humans need for respiration.

How is it used in Rockets?

• Helium is used to pressurise fuel tanks, ensuring fuel flows to the rocket’s engines without interruption; and for cooling systems.
• As fuel and oxidiser are burned in the rocket’s engines, helium fills the resulting empty space in the tanks, maintaining the overall pressure inside.
• Because it is non-reactive, it can safely mingle with the tanks’ residual contents.

Is it prone to leaks?

• Helium’s small atomic size and low molecular weight mean its atoms can escape through small gaps or seals in storage tanks and fuel systems.

But because there is very little helium in the Earth’s atmosphere, leaks can be easily detected - making the gas important for spotting potential faults in a rocket or spacecraft’s fuel systems.