Two NASA astronauts aboard Boeing’s Starliner will stay on the International Space Station for months because of a faulty propulsion system whose problems included helium leaks.
Back on Earth, SpaceX’s Polaris Dawn mission, which finally launched on Tuesday, was delayed because of helium issues on ground equipment.
Past missions that have been affected by pesky helium leaks include ISRO’s Chandrayaan 2 and ESA’s Ariane 5.
Why do spacecraft and rockets use helium?
Helium is inert — it does not react with other substances or combust — and its atomic number is 2, making it the second lightest element after hydrogen. Rockets need to achieve specific speeds and altitude to reach and maintain orbit. A heavier rocket requires more energy, not only increasing fuel consumption but also needing more powerful engines, which are more expensive to develop, test, and maintain. Helium has a very low boiling point (– 268.9 degree Celsius), allowing it to remain a gas even in super-cold environments, an important feature because many rocket fuels are stored in that temperature range.
How is helium used in spacecraft?
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. The frequency of helium leaks across space-related systems, some engineers say, have highlighted an industry-wide need for innovation in valve design and more precise valve-tightening mechanisms.
Source: Indian Express, 14/09/24
