NASA’s Artemis II mission, originally scheduled for launch on February 8, has been pushed back by at least a month due to a hydrogen leak discovered during tank fuelling. This delay mirrors the challenges faced by the first Artemis mission, which also experienced setbacks linked to fuel leaks.
The peculiar properties of liquid hydrogen and liquid oxygen, the key components of rocket fuel, make them prone to leakage despite being extremely cold substances. Liquid hydrogen, with a boiling point of -253 C, and liquid oxygen, with a boiling point of -183 C, operate at temperatures near absolute zero, instantly freezing anything they come into contact with.
To prevent these cryogenic liquids from vaporizing, extensive measures are taken to insulate them from the surrounding warm environment. The Space Launch System (SLS) rocket’s core stage is coated in insulating foam to shield the cold fuel from the ambient heat. Additionally, the fuel lines and tanks must be pre-chilled to avoid premature vaporization.
Despite these precautions, the combination of frigid temperatures and vapor pressure often leads to leaks, especially with hydrogen, known for its ability to escape through tiny openings. The fuels are stored near the launch pad and transported through a complex network of pipelines and hoses to the rocket’s engines, presenting multiple opportunities for leaks.
During a recent wet dress rehearsal, a leak was detected at the connector linking the hose on the launch tower to the rocket, a recurring issue that previously caused significant delays. Engineers are working to address the leak onsite, aiming to avoid lengthy repairs and expedite the launch process, now targeted for no earlier than March 6.
While hydrogen leaks have been a persistent challenge in space missions, NASA continues to utilize this fuel for its high thrust-to-weight ratio, crucial for heavy lift vehicles like the SLS rocket. However, critics argue that the SLS’s reliance on liquid hydrogen and its disposable nature make it costly compared to reusable rockets used by private companies like SpaceX.
Moving forward, the success of the SLS rocket hinges on resolving hydrogen leak issues while navigating the balance between operational costs and job preservation for those involved in its construction.