I strapped some nuclear engines onto the Twain and tried to get an encounter projection for Duna...but couldn't for some reason. But an encounter for Jool (the gas giant of the system) came up, so I headed out there with no real plan. The trajectory was poor (I'm not so good at this interplanetary stuff yet), and I barely got into orbit around Jool, but with nowhere near enough fuel to get home. Here is the Mark Twain 3 ship in orbit around Jool.
Aerobreaking to lower the orbit. The aerobreaking was very fierce at 120 km, but unnoticeable at 180 km.
Here is the ship passing Leythe, a moon with an ocean and probably substantial atmosphere. An excellent future target.
Since there was no way home, Jebediah decided to take one of the landers down into the gas giant... but the ship exploded at low altitude when it hit sudden violent winds.
Bob and Bill decided to drop in with the main capsule, and the descent was good until the the violent winds hit at about 100 meters above the "surface" and ripped the cute off. But the capsule did not fall or get crushed...instead it was bobbing around approximately 100 meters above the "surface" altitude, getting buffeted very violently every few seconds. An EVA in this wind was....not pretty.
The ship worked well enough to get out to the Jool system, so I think it will do well at Duna and other targets with better planned trajectories, once I figure out how to use that navi tool. I think the problem was that I was encountering moons along my path and the navi calculator would not look beyond that encounter to the next one.