Greetings fellow KSP'ers, To those who have mastered interplanetary flight I ask for your advice, inquiry and assistance. I have successfully put a kerbed lander on Duna, however my previous design was limited and my lander doesn't have enough fuel to return back home or even get back into Duna Orbit. So I am designing a new interplanetary mothership that will not only rescue the crew from Duna, will also serve on other interplanetary explorations to other worlds. Here are a couple of photos, attached to the post. (Note, I have yet to assemble the first and second stages...for now please focus on what I have.) As you can see below the payload I am trying to take into orbit is composed of two parts. One the powerful "mammoth" engine block which will give the final push into orbit and perhaps give some delta-v for the Duna burn assuming enough fuel is left. The other half, which is the one I'd like to focus on is the "Endurance Module". It is two be powered by 6 nuclear rockets, with 1 jumbo x64 orange fuel tank, a smaller x16 white fuel tank, a equipment storage container, a "hitchhike" contanier for possible crew, two large batteries, 6 fins, 12 1x6 solar pannels and two dockports(one on the top and one on the bottom.) Also note I plan to attach a fuel lander that will go to the surface and rescue the boys. The Module weighs about 100 tons and total configuration(with the rocket stage below) is about 225 tons. I've previously tried to design a mothership using mainsail rockets and that failed catastrophically. I realize now that nuclear rockets provide the best bang for the buck(they have the best efficiency), however I'm a little uncertain how they will preform due to their low-thrust so I might have to rethink my burn strategy. So for all those who are pros at getting to other planets can you spare some advice on my design as it is. Should I add more tanks, add more rockets, get rid of some containers, scrap it completely, keep it as it is? Anything I should do? Also I would greatly appreciate advice for nuclear rockets because I have never used them before and I don't know what maneuvers I should do because I know they will behave differently then the conventional rockets. Please spare any constructive criticism or advice you have to helping me get of the launch pad, and rescue my guys stranded on Duna currently. Thank you so much!!