> Morton (tehnically, Morton Norwich) made other chemicals as well, including rocket fuel. The fuels were marked up so highly, that - together with a company called Thiokol - they decided they could make and fly the whole rocket engine cheaper than NASA could.
That's...not really true. Thiokol and Morton Norwich merged in 1982; Morton-Thiokol did a lot, wasn't centered on a proposal to “make and fly the whole rocket engine cheaper than NASA could”, and, in fact, the rocket engine business they had after the merger was the same one Thiokol had before the merger, just with the new entity’s name. Thiokol had been a contractor on the shuttle program since the 1970s.
> Their first attempt at rocket building was the Challenger, which blew up less than two minutes after launch
No, it wasn't. Thiokol was the contractor for the SRB motor segments from well before the merger, and Thiokol and then Morton-Thiokol made the motor segments for the SRBs for all of the launches before the 1986 Challenger disaster (and all of them after, though some under different names, after Thiokol was purchased.)
> and the Morton-Thiokol partnership.
Morton-Thiokol wasn't a partnership, but it's true that most of the chemical business was spun out as Morton in 1989, with the propulsion business staying as Thiokol. This wasn't really an unwinding of the merger; Thiokol had a substantial chemic business before the merger. It was a novel split of the combined business that happened to use the branding from the old components because it was available.