So I'm generally not very ambitious, and my interplanetary missions have been imprecise to the point where they barely make it. Today I had the idea to build a ship specifically for interplanetary transit. The idea was to make something with large crew and fuel capacity. It would be sent between planets, with stations that are already there to perform orbit-to-ground work, and vice-versa. After some time in the VAB, I launched Space Bus. screenshot26b by dizzle229, on Flickr It was surprisingly easy to get into orbit, which I thought would be the major hurdle. I've yet to send it anywhere, but I can already predict some problems. 1. Every body needs a fuel station to keep the wheels on Space Bus going round and round. In addition, every fuel station needs to be refueled itself. 2. Very long burn times. Even with four LVNs, this thing doesn't get close to 1G of thrust. I fear that since a transfer burn would have to be performed over multiple passes, it might end up at a stage where it's at Kerbin-escape-velocity, and not enough time left to complete the burn in the right position. Slapping on some higher-thrust engines means sacrificing ISP, and even now it only has about 10 km/s Delta-V. Not sure how much the external tanks will add to that. 3. Going off of the last one, slowing into orbit around bodies. With such low thrust, is it even capable? That 10 km/s may sound like a lot, but I don't want to try aero-braking this thing. This thread isn't so much about this particular craft as it is about the concept, the problems inherent in the concept, and hopefully, solutions. Have you guys tried something like this? Is it worth the trouble? I've always seen people building motherships and wondered how they'll fare when they have to aero-brake.