As an experiment, KSEA decides to test the capabilities of the Explorer 5 spacecraft. Having returned from Duna, is it capable of entering Duna orbit again, and returning safely to Kerbin orbit? If so it would provide a much more cost effective means of transporting Kerbals to and from the red planet.
The new Discovery-class spacecraft design is certainly capable of the trip, however it is overkill to the extreme – DSV-2 Discovery could travel to Duna, return to Kerbin, and repeat the trip without ever needing to refuel!
Gillian, Shepely, and Seely (the current crew on Kerbin Spaceport) start work refuelling Explorer 5 for it’s next mission!