Also: Methalox rockets are proving to be a better choice than hydrogen powered rockets, and while you could store methane in that tank, it's about the most expensive way possible to store methane per litre.
More SLS brain damage.
More SLS brain damage.
SLS is planned as an expendable launch system that will put spacecraft far beyond Earth orbit. They need the specific impulse that hydrogen offers.
And in related news, liquid hydrogen is going to become just as mainstream as LNG is today, within a decade from now. All the major LNG ship builders (KHI, GTT etc.) are building and testing LH2 transport ships as we speak. Suiso Frontier began operational sailing more than a year ago.
On top of that cryo methane and oxygen are at closer temperatures than hydrogen and oxygen, which simplifies storage further.
So effectively the difference is that Hydrogen embrittles everything and makes development more expensive even without reuse considerations, making Methane superior unless you're SLS and being wasteful is a feature.
Either way it's disappointing NASA is determined to keep the Space Shuttle's white tech elephant going.
The only reason to not design a reusable launch system in the past 7 years is because you lack foresight, or you have a design by committee where you're being forced into poor decisions for political gain.
They wanted it, sure: there's more than one way to build a big rocket, and the choice that Congress/NASA made was to use hydrogen on a sustainer stage.
They could have made other choices.