According to NASA, the leak occurred in an eight-inch-long supply line called a “quick disconnect” that is used to inject propellant into the SLS’s core stage. That means there have been four leaks of liquid hydrogen since the giant lunar launch vehicle was pushed onto the launch pad at the Kennedy Space Center.
While liquid hydrogen is considered a more efficient fuel for rocket launches, managing it is very difficult because it is the lightest element in the world. Even the tiniest openings allow tiny hydrogen atoms to escape, which is one reason why Musk decided to switch SpaceX rocket engines to methane.
Musk tweeted: “The Raptor engine was originally designed with liquid hydrogen, but switched to methane. Methane is the best combination of efficiency and ease of operation.” He also said that the use of liquid hydrogen and methane as a When propellant, the velocity difference is small, and methane requires smaller containers and less insulation.
Also, methane is easier to produce on Mars, which is important for launch missions. SpaceX was one of the first companies to use liquid methane and liquid hydrogen as rocket fuel. Musk hopes to have self-sufficient cities on the red planet in 20 years, and his company is preparing to use Starships to transport people and cargo to the moon, Mars and beyond.
So far, SpaceX has developed five engines, Merlin, Kestrel, Draco, SuperDraco and Raptor, for its Falcon 9 rocket, Dragon spacecraft and Starship. In addition to methane, SpaceX uses liquid oxygen and rocket-grade kerosene (RP-1) propellants for the Merlin engines on the Falcon 9 rocket, while the Raptor engines on Starship use a combination of methane and liquid oxygen as fuel.
Despite the tedious task of handling and preserving liquid hydrogen during refueling operations, NASA has continued to use liquid hydrogen due to a policy mandated by the U.S. Congress. It is reported that the US Congress in 2010 directed NASA to use the kinds of engines and propulsion systems in other hardware of the SLS, which were used in the space shuttle program many years ago.
Currently, NASA allows a leak of up to 4 percent of liquid hydrogen during propellant fueling of a rocket. However, the most recent leak of liquid hydrogen on Saturday was more than twice the maximum threshold. Still, despite these troubles, liquid hydrogen is considered a viable propellant option because it provides better thrust for the rocket during launch. The SLS rocket core stage storage tank has a liquid hydrogen capacity of 538,606 gallons and a liquid oxygen capacity of 19,000 gallons. (small)