I mean there are lots of resources: Essentially the Senate in 2011 wrote a bill that mandated NASA to build a rocket by 2016 AND that uses existing contractors

I mean there are lots of resources: Essentially the Senate in 2011 wrote a bill that mandated NASA to build a rocket by 2016 AND that uses existing contractors. So there was literally no way other then just using exiting Shuttle components to even attempt to do that. This reddit thread has a lot of resources about the actual design of what SLS ended up being and how the design process clearly suggest to NOT DO what they eventually did: https://old.reddit.com/r/SpaceLaunchSystem/comments/kt1vlf/rac_stuff_summary_kinda_idk_anymore/ https://old.reddit.com/r/SpaceLaunchSystem/comments/kt1vlf/r... Eric Berger form Ars Technica has lots of articles on the topic, see: https://arstechnica.com/science/2022/08/former-nasa-official-on-trying-to-stop-sls-there-was-just-such-visible-hostility/ https://arstechnica.com/science/2022/08/former-nasa-official...