> NASA and its cost-plus contractors decided the RS-25 was the perfect engine for a disposable rocket NASA did no such thing. They were ordered to use the engi

> NASA and its cost-plus contractors decided the RS-25 was the perfect engine for a disposable rocket NASA did no such thing. They were ordered to use the engine by the Senate. (When the Constellation program was canceled and the SLS program was created, Senate ordered NASA to pick solutions that "minimize contract cancellation costs". Not minimize total costs, minimize costs related to cancelling contracts. This of course means that the contractors you are already using can offer any solution they want, at any price they want, and so long as they are willing to waive the contract cancellation penalties as part of their package, you have to pick that solution. They all offered a really expensive, really bad deal. I know several NASA engineers who quit in disgust because of this.)