- NASA Artemis 1 moon mission has been postponed indefinitely due to a liquid hydrogen leak in the spaceship.
- NASA has a maximum of 4 percent hydrogen leakage tolerance, and anything above that is considered a flammability hazard.
- Elon Musk suggests switching to a combination of liquid methane and oxygen as a fuel.
NASA Artemis 1 moon mission got postponed twice – August 29th and September 3rd – after the NASA crew witnessed leakage while loading liquid hydrogen into the Space Launch System (SLS) rocket. The crew spotted a leak in the quick disconnect – an eight-inch supply line used to fill and empty the propellant into the SLS’s core stage. This will be the second time Kennedy Space Center saw liquid hydrogen leak in the uncrewed Artemis 1-moon mission rocket’s launch pad.
In an Ars Technica post, Chris Berger explains that NASA has a maximum of 4 percent hydrogen leakage tolerance during the loading into a rocket. During the September 3rd launch, the leakage was twice this tolerance level. NASA considers anything above 4 percent hydrogen leak as a flammability hazard. However, even after going through so much hassle, NASA continues using liquid hydrogen as fuel, citing a mandatory policy by the US Congress.
Accurate assessment. Raptor design started out using H2, but switched to CH4. Latter is best combo of high efficiency & ease of operation imo.— Elon Musk (@elonmusk) September 4, 2022
Delta-v difference between H2 & CH4 is small for most missions, because CH4 tank is much smaller & no insulation is needed.
This is why Elon Musk switched to methane fuel for his rocket engines. The Musk-owned SpaceX has five engines in its arsenal: Merlin, Kestrel, Draco, SuperDraco, and Raptor. These engines use methane, liquid oxygen, and rocket-grade kerosene as fuel. However, Raptor uses a combination of methane and liquid oxygen.
The prime reason to use liquid hydrogen in space crafts is its efficiency, which means it provides a better mileage for rocket engines, which is why liquid hydrogen is considered a viable fuel, and US Congress mandated NASA use it for its SLS rocket alongside other hardware. Although liquid hydrogen is a viable fuel for rocket engines, it is challenging to manage because hydrogen is the lightest element, and a small opening could result in drainage.
NASA has the next launch opportunity between September 19th to October 4th and October 17th to October 31st to execute its uncrewed Artemis 1 moon mission.