So here's my take on an interplanetary exploration vehicle--I call it, lamely, the X-4, since X 1-3 had a tendency to juuuuust miss making their orbits at launch. Necessary mods are below--but first, the pics! , , , ,Mechanical Mouse: http://kerbalspaceprogram.com/forum/showthread.php/13692-0-16-Mechanical-Mouse-Industries?highlight=mechanical+mouse Mechjeb: http://kerbalspaceprogram.com/forum/showthread.php/12384-PLUGIN-PART-0-16-Anatid-Robotics-MuMech-MechJeb-Autopilot-v1-9 Powertech: http://kerbalspaceprogram.com/forum/showthread.php/9034-Collection-0-15-0-16-PowerTech-v0-2-6 -Make sure to grab the Powertech-Mumech adapter plugin. Note--my version also has the aviation lights plugin-- http://kerbalspaceprogram.com/forum/showthread.php/16925-PLUGIN-PART-0-16-Aviation-Lights-v1-0?highlight=aviation+lights --but it's not necessary to run the attached craft file. I *believe* these are all the mods that I used, let me know if anything is broken. The launch vehicle is compact, and handles nicely. I just turn on ASAS and let 'er rip. Incline to 45 degrees as you leave the atmosphere and you should reach a stable orbit and still have almost full tanks in the final liquid rocket stage--staging is set up so you can fire them in tandem with the ion engines, so you should easily reach escape velocity. You do have to use those liquid fuel stages wisely--the ion engines may not stabilize your orbit in time. You can bring space junk to zero by decoupling the final booster stage just before reaching escape velocity, and then boost the rest of the way on the ion engines. The funnest part for me is the 3 RCS landers--plug in any hardware you can carry, and you can customize it for just about any mission. The main drawback is that you can't drop probes at multiple targets--with only one or two on board, you'll go tumbling through space. Landing the X-4 itself isn't recommended... but that never stopped a kerbal. Also--please post any modifications to the design in this thread--I've got a few vehicles based on this design, and I'd like some new ideas.