[portillo]

I agree, this was the real reason why the project failed. Moreover, it was not clear at all that fractionation would bring any lifecycle costs savings, neither that any of the alleged extra flexibility (and maneuverability, resiliency, maintenability, and other -ilities) would result in any added value for the missions.

Fractionation is very hard,it introduces a lot of complexity in the design and interfaces, and it requires lots of coordination between multiple vendors. Project Ara by Google (a modular cellphone similar to Phoneblocks) also vouched for this idea of fractionation (and in fact was also led by Paul Ermenko) and was also cancelled.