NASA’s Artemis II mission, originally scheduled for a Feb. 8 launch, has been postponed by at least a month due to a hydrogen leak detected during tank fueling. The previous Artemis mission also encountered delays caused by fuel leaks.
The peculiar properties of liquid hydrogen and liquid oxygen, the key components of rocket fuel, make them prone to leakage despite their extremely low temperatures. Oxygen, typically a gas at room temperature, turns into a liquid below -183°C, resembling pale blue water. Liquid hydrogen, even colder with a boiling point of -253°C, can freeze anything it touches instantly.
Handling such frigid liquids requires specialized equipment that can withstand the temperature variations between the fuels and the warm Florida air where rockets are launched. Insulating foam covers the core stage of the giant Space Launch System (SLS) rocket to protect the cold fuel from the environment. Pre-chilling the fuel lines and tanks is essential to prevent leaks.
The cryogenic fuels’ ultra-cold temperatures and vapor pressure lead to leaks, particularly hydrogen, which can escape through the tiniest openings. The fuels are stored near the launch pad, piped up to the rocket through the launch tower, and transferred to the engines through complex plumbing systems.
During a recent wet dress rehearsal, a leak was identified at the connector linking the hose on the launch tower to the rocket. Engineers are working to address the issue on-site to avoid returning the rocket to the Vehicle Assembly Building, saving time and resources. Another rehearsal is planned before the rescheduled launch no earlier than March 6.
NASA’s reliance on liquid hydrogen as fuel, despite its leakage challenges, continues due to its high thrust-to-weight ratio, beneficial for heavy lift vehicles. Critics argue that the SLS rocket’s high cost and disposable nature make it unsustainable compared to reusable rockets by private companies like SpaceX. The future of the SLS rocket hinges on resolving hydrogen leaks while considering cost-effectiveness and job preservation for contractors.
In conclusion, addressing the technical challenges associated with liquid hydrogen leaks will be crucial for the sustainability of NASA’s SLS rocket program.
