[zeristor]

“However, the real answer is that Congress mandated that NASA continue to use space shuttle main engines as part of the SLS rocket program.”

Why? The article states that Space Shuttle technology is 40 years old, isn’t it more like 50.

The hope was that the Space Shuttle could be launched and boost Skylab into a higher orbit, I wonder what that future might have been like, how long would Skylab have lasted?

[mytailorisrich]

"In 2010, when Congress wrote the authorization bill for NASA that led to creation of the Space Launch System, it directed the agency to "utilize existing contracts, investments, workforce, industrial base, and capabilities from the Space Shuttle and Orion and Ares 1 projects, including ... existing United States propulsion systems, including liquid fuel engines, external tank or tank related capability, and solid rocket motor engines."

Lots of financial and industrial interests, constituents' jobs, donors' money, on the line.

[brudgers]

Why?

Because the Tyranny of the Rocket Equation has not been over-thrown.

https://www.nasa.gov/mission_pages/station/expeditions/exped...

Doing so would require a universe with different physics.

[zeristor]

Eh?

Liquid Hydrogen doesn’t seem a good choice for first stage rockets. Similar delays to the Space Shuttle launches that must be hugely expensive to have a whole team to have to standby for a few days.

Methane as used more now can be chilled more than the boiling to store the fuel when it is more dense, and is handy for reusable engines since it doesn’t produce nearly so much soot.