This book has many illustrations of alternate designs considered before the Space Shuttle was finalized
https://www.amazon.com/Shuttle-History-Developing-National-T...
as well as the results of late 1980s-early 1990s studies that considered the possibility of putting together Space Shuttle parts in different ways. Say you could have a bigger external tank, four solid rocket boosters instead of two, and a big-ass orbiter which has five engines instead of three. (That one probably is too much of a boondoggle because they'd have to spend a few billion dollars making a bigger launchpad!)
You might think that, with the research done to develop the parts, it would be cost effective to build something new from Space Shuttle parts but in those studies it was always outrageously expensive to build anything out of Space Shuttle parts because... Space Shuttle parts are stupendously expensive.
In an alternate universe something like the SLS (a non-reusable big-ass booster with lots of stages) could be a lot cheaper than the SLS if it was cost-optimized, but cost-optimization itself isn't cheap!
By contrast to that, the Starship model isn't proven either. Reusable Starship to LEO could be a good business, but orbital refueling is still unsolved and even if it is perfected, current plans are to launch 12-20 Starships to land and return maybe 3 tons from the moon. Think of what a huge thing you could build in LEO if you had 20 Starships!
This book has many illustrations of alternate designs considered before the Space Shuttle was finalized
https://www.amazon.com/Shuttle-History-Developing-National-T...
as well as the results of late 1980s-early 1990s studies that considered the possibility of putting together Space Shuttle parts in different ways. Say you could have a bigger external tank, four solid rocket boosters instead of two, and a big-ass orbiter which has five engines instead of three. (That one probably is too much of a boondoggle because they'd have to spend a few billion dollars making a bigger launchpad!)
You might think that, with the research done to develop the parts, it would be cost effective to build something new from Space Shuttle parts but in those studies it was always outrageously expensive to build anything out of Space Shuttle parts because... Space Shuttle parts are stupendously expensive.
In an alternate universe something like the SLS (a non-reusable big-ass booster with lots of stages) could be a lot cheaper than the SLS if it was cost-optimized, but cost-optimization itself isn't cheap!
By contrast to that, the Starship model isn't proven either. Reusable Starship to LEO could be a good business, but orbital refueling is still unsolved and even if it is perfected, current plans are to launch 12-20 Starships to land and return maybe 3 tons from the moon. Think of what a huge thing you could build in LEO if you had 20 Starships!
This book
https://www.amazon.com/Shuttle-History-Developing-National-T...
has wonderful illustrations of many of the hundreds of designs they considered before settling on what was to be the Space Shuttle and also talks about late 1980s studies that considered various ways of putting together Space Shuttle parts to make different vehicles (say a big-ass orbiter with more engines, a bigger ET and more SRBs) The hope was that you could reuse the development work that went into Space Shuttle parts but it seemed like anything you made out of Space Shuttle parts was unaffordable no matter what you tried.
You could certainly develop parts that are cheaper on a per unit basis but would it be worth developing them for the number you would make?
The US doesn't really have an attractive answer to getting to the moon or for aggressive deep space missions, Starship doesn't look great. Growing up in the 1980s I read the "Science Fact" columns in Analog Science Fiction magazine and was told that NASA sold us out and we could have had a much more intensive lunar program but really the architecture Apollo used was brilliant and much more achievable than everything else they considered.