https://old.reddit.com/r/SpaceLaunchSystem/comments/kt1vlf/r...
Basically a Saturn V like clone was considered.
And those studies referenced also didn't consider many other viable options. Commercial providers were planed to be able to bid as well and SpaceX and ULA would have considered making bids.
Something NASA also didn't consider is using the Merlin engine, an engine that actually existed and was already going into mass production at that time. That would have been an alternative to F-1 and would have been ready sooner.
You also might be interested in this presentation from 2011:
https://www.youtube.com/watch?v=IweLWCBHpUE%3Ft%3D0
What funny about that presentation is how much time he spends talking about cost and how cost control is the most important thing and if they can control cost NASA shouldn't even make its own rocket. And of course SLS did the exact opposite of controlling cost.
And even if you assume they fail, the bids were expected to be in the 2-5 billion $ range.
Not in the 20 billion+ $ range. And those bids would have been for a 130 ton rocket, not a 90 ton rocket like SLS is.
> I'd also question cost estimates based on nothing actually built or seriously planned through.
You can question it, but those kinds of estimates are what NASA bases it choices on. And NASA picked what their own estimations suggested was the worst thing.
Go look at some of the studied NASA internally did, their result was the same, other approaches would have been better and cheaper in the long run.
The Shuttle derived architecture won because of politics.