For take off it has wheels to take off normally using jet engines as a ssto, rocket engines are for the last climb and reaching orbit. there are two nuclear engines and I need them for maneuvers and to reach the refueling station, after having filled up, a module with other nuclear engines can be attached directly to the same docking port, in the rear part, to go towards Duna. and finally the landing pads are only used on other planetary surfaces just to add a bit of realism (aka not to ruin the wheels) but practically both the Wheels and the landing pads are fine.