Critics of reusing Explorer 5 were correct! The spacecraft didn’t have enough deltaV to overcome the high speed approach of Duna. Perhaps KSEA should have known better!
“Hmmm. Well, we all make mistakes! Back to the drawing board! It would be nice to have a spacecraft that can reach Duna without being quite a DSV-class vehicle!”
To that end, KSEA begins work retooling what would have been Explorer 7 to use the Explorer design but with a more re-usable layout in mind!