Here's a nice factoid from it:

> circa 1970 Accidental production of first glass bubbles at 3M plant in Guin, AL

> circa 1975 Cryogenic research testing by G. R. Cunnington and C. L. Tien at UC Berkeley

I wonder what is the long-term future of these tanks?

10 years from now, SLS will likely be winding down. Few see it as the long-term answer. How long it has to last, really depends, I think, on how quickly SpaceX can get Starship operational.

Once SLS is finally mothballed – whether that happens in 5 years or 10 – then what happens to all this hydrolox infrastructure? Methalox can use the oxygen tanks, but how feasible would it be to put methane in the hydrogen tanks?

The answer is given in the slides; Potential for use in global logistics supply chains of LH2 storage and transfer.

One has to wonder how likely such a future use actually is going to be.

Opinions vary widely as to how much adoption hydrogen is actually going to see in coming decades. Attempts to commercialise it thus far have seen quite limited success, and sceptics who question whether there will be any greater success in the future could be right.

Even if those sceptics are wrong, and the "hydrogen economy" really takes off – how close is this hydrogen storage infrastructure going to be to the actual supply, demand and transit points? It might turn out to be in an inconvenient location given the geography of the supply chain, and end up seeing little use as a result. Is the fact that this is right next to a rocket launchpad – which I assume will still be in use for decades to come, even if not for SLS – going to impose a limit on potential non-space uses?

It's a big tank, but not so big it couldn't be shipped anywhere in the world it is needed and reassembled.

What’s the cost per liter of this tank vs. the one built in the 1960s?

They can build earthworks, it's not too bad. It's similar to Manhattan Island for example, unless there's a catastrophic failure of planning and action, they can build a sea wall around it and put storm surge control devices in the rivers.

Remind me how Manhattan fared during Sandy?

Being right beside the sea is a feature, to improve range safety by launching over the sea.

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.

Methalox can be a better choice if you are designing a reusable launch system and you are optimizing for low cost to orbit.

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.

Methalox ends up being preferable because Hydrogen ends up performing relatively similarly when accounting for the extra tank mass needed to effectively contain it (both in terms of thicker walls and larger tanks in general). Methalox can't achieve Hydrogen ISPs but in exchange it's much easier to contain, allowing for much lighter and simpler tanks, resulting in similar deltaV overall.

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.

It's been a while but it seemed to me that high ISP isn't very big win for the first stage anyways. Basically linear with everything being equal which as you mention it isn't. So slightly lower ISP means slightly heavy first stage.

Either way it's disappointing NASA is determined to keep the Space Shuttle's white tech elephant going.

Low cost to orbit is the whole ball game. If you have that, everything else is dramatically easier. Not optimizing for that is, as the grandparent comment put it, brain damage. (AKA politics)

The private space industry interprets brain damage as damage and routes around it.

> Methalox can be a better choice if you are designing a reusable launch system and you are optimizing for low cost to orbit.

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 need the specific impulse that hydrogen offers.

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.

It's rising at one foot per century, so they've got some time.