Hydrogen rockets need to have huge fuel tanks, hydrogen rockets have low thrust - the space shuttle needed boosters to lift off
Everything in space is a trade off, kerosene is better in all those ways than methane, but you can make methane on Mars. The global warming potential isn’t much as there are so few rocket launches, and hydrogen fuelled rockets use fossil hydrogen (made from fossil methane (aka natural gas)) because it is cheaper than alternatives
Regarding rocket propellant
Methane is more dense than hydrogen
Methane makes more thrust than hydrogen
Hydrogen rockets need to have huge fuel tanks, hydrogen rockets have low thrust - the space shuttle needed boosters to lift off
Everything in space is a trade off, kerosene is better in all those ways than methane, but you can make methane on Mars. The global warming potential isn’t much as there are so few rocket launches, and hydrogen fuelled rockets use fossil hydrogen (made from fossil methane (aka natural gas)) because it is cheaper than alternatives
deleted by creator
Saturn V stage 1 ran on kerosene (RP-1) and liquid oxygen
Stages 2 and 3 were hydrogen.
The rocket you want, to use space hydrogen, is the bussard ramjet, which unfortunately isn’t expected to work
deleted by creator