Elon Musk weighs in on Artemis 1 launch scrub; has THIS suggestion for NASA team

NASA, on Saturday, decided to postpone the launch of Artemis 1 after the mission teams encountered leakage while loading liquid hydrogen into the Space Launch System (SLS) rocket. According to NASA, the leak was in an eight-inch supply line, called the quick disconnect, which is used to fill and drain propellant into the core stage of SLS. This marked the fourth infamous instance of liquid hydrogen leak since the mega Moon rocket was rolled out to the launch pad at the Kennedy Space Center.

What Elon Musk thinks 

While this class of fuel is considered efficient for rocket launches, it is extremely difficult to manage since hydrogen is the lightest element in the universe. Even the slightest opening allows the tiny hydrogen atoms to escape which is why SpaceX CEO Elon Musk decided to switch to methane for one of his rocket engines. 

"Raptor design started out using H2 (hydrogen), but switched to CH4 (methane). Latter is best combo of high efficiency & ease of operation imo", Musk tweeted. He also said that the difference in velocity upon using hydrogen and methane as propellants is minimal and the latter needs a smaller tank with less insulation. 

SpaceX, so far, has developed five engines-- Merlin, Kestrel, Draco, SuperDraco, and Raptor-- which are used in its Falcon 9 rockets, Dragon spacecraft, and Starship vehicle. Apart from methane, SpaceX also uses liquid oxygen and rocket-grade kerosene (RP-1) propellant for its Merlin engines used in Falcon 9 whereas the Raptor engines in Starship use a combination of Methane and liquid oxygen as fuel. 

Why does NASA use liquid hydrogen?

Despite the cumbersome task of handling and preserving liquid hydrogen during tanking operations, NASA continues to use liquid hydrogen owing to a mandatory policy by the US Congress. According to Eric Berger's report in Ars Technica, Congress in 2010 directed NASA to use engines and propulsion systems among other hardware, for SLS, that were once used during the Space Shuttle program years ago. 

Currently, NASA allows a maximum of 4% leak of hydrogen during propellant loading into the rocket, however, the recent leak on Saturday was over twice this amount. Despite all these mandates, liquid hydrogen, however, is considered a viable propellant option as it provides better mileage to rockets during launch. The SLS rocket's core stage tank has a capacity of 5,38,606 gallons for liquid hydrogen and 1,96,000 gallons for liquid oxygen.