NASA’s Artemis II mission, originally scheduled for a Feb. 8 launch, is now postponed by at least a month due to a hydrogen leak discovered during tank fueling. The prior Artemis mission also encountered delays caused by fuel leaks.
The unique characteristics of liquid hydrogen and liquid oxygen, the components of rocket fuel, make them prone to leaks despite being extremely cold. Liquid hydrogen has a boiling point of -253 C, while liquid oxygen’s is -183 C, requiring specialized equipment to handle such frigid temperatures without freezing or cracking.
To prevent the cryogenic fuels from vaporizing, the core stage of the massive Space Launch System (SLS) rocket is insulated with orange-colored foam. However, the ultra-cold temperatures and vapor pressure lead to leaks, particularly with hydrogen, the smallest molecule that easily escapes through pipelines and valves.
The recent hydrogen leak during a wet dress rehearsal stemmed from a connector on the launch tower, similar to an issue faced during the Artemis I flight. Engineers aim to rectify the leak at the launch pad to avoid delays, with a new launch target set for no earlier than March 6.
NASA’s continued use of liquid hydrogen, despite its leak challenges, is rooted in its superior thrust-to-weight ratio, crucial for heavy-lift vehicles like the SLS rocket. Critics argue that the SLS is costly and disposable, unlike reusable rockets by private companies like SpaceX, which use methane fuel and operate at a fraction of the cost.
The future of the SLS rocket hinges on resolving hydrogen leaks while addressing the balance between flight costs and job retention for contractors across various states involved in NASA technology development.