NASA’s Artemis II mission, initially scheduled for launch on February 8, has been postponed by at least a month due to a hydrogen leak discovered during tank fuelling. The preceding Artemis I mission also encountered delays caused by fuel leaks.

The unique properties of liquid hydrogen and oxygen as rocket fuel, with extremely low boiling points of -253 C and -183 C respectively, make them prone to leakage due to their frigid nature. To prevent freezing or cracking of equipment in contact with these cryogenic liquids, special measures are taken to insulate and pre-chill the fuel lines and tanks.

The orange color of the Space Launch System (SLS) rocket’s core stage is due to insulating foam applied to shield the cold fuel from external warmth. Despite such precautions, the cryogenic fuel’s vapor pressure leads to leaks, especially with hydrogen being highly volatile and able to escape through the tiniest openings.

The recent delay was caused by a leak at the connector joining the hose on the launch tower to the rocket. Engineers aim to address this issue at the launch pad to avoid returning the rocket to the Vehicle Assembly Building. Another wet dress rehearsal is planned before the rescheduled launch no earlier than March 6.

NASA’s choice to use liquid hydrogen for its rockets, despite the propensity for leaks, is rooted in the fuel’s high thrust-to-weight ratio, ideal for heavy lift vehicles. This decision also supports job creation across various states involved in NASA technology projects.

Critics argue that the SLS rocket’s high cost and disposable nature make it unsustainable compared to reusable rockets used by private companies. The future of the SLS rocket hinges on resolving hydrogen leak issues while balancing the economic viability of its operations and the job security of its workforce.