I decided to do a more near-time lower tech ship for a change, something that could be feasibly built in thirty years. Normally I avoid the first half of this century. The future history on my web site begins in 2052 for a reason. Mainly, I'll be eighty-seven the day before that year begins, and when I first started drafting that history over twenty years ago, I figured I'd be dead or senile by then, and wouldn't care if I was wrong. Then again, it also starts with a world war (a convenient cusp to clear away whatever happens in the first half of the century) so it wouldn't hurt my feeling too much to see it not come to pass. And little did I know my grandpa would make it to a hundred with his wits mostly intact, so I might be grumbling a bit in forty-four years... Anyway, this ship design is not too much of a technological stretch. I speced it out on a spreadsheet, using what amateur rocket science I know, and only made a few "reasonable" tech advancements. The interesting thing is that the biggest limitation on the ship isn't some new fancy engine. It's power. For this design, I imaged a pebble bed fission reactor. I couldn't get good figure for the mass of ship reactors (go figure - Navy has its secrets), so I faked it a bit. The black and yellow reactor in the back has a sustained generating capacity of 218 MW, and I decided I could increase the efficiency to 70% - but even at that rate, those four big radiators at the back are still putting out 1000K the whole trip. But with that power limitation, the ion-like engines I envisioned don't actually outperform what we can accomplish in the lab (~20,000isp). In fact, to get to Jupiter at constant thrust (of about a millimeter per second squared acceleration), you'd want to run them at half that exhaust velocity. Yeah, gibberish to most of you. Anyway, the biggest fudges are that the whole front section (forward of the landers) only weighs thirty tons, and for that to work and hold the crew of six, you need to have light materials and a closed life support system. Plus I didn't want to include shielding mass, so the big tanks hold liquid hydrogen (for an initial boost and return at higher thrust) and water tanks in the back black part of the habitat modules act as more shielding. I'll do an annotated "tech drawing" if people express an interest. Thanks for viewing and commenting! --- The Archimedes class explorer was the first spacecraft designed for repeated expeditions to the outer planets. The Archimedes, Tsiolkovsky and Goddard completed seven missions to four gas giants, including the only antebellum explorations of Uranus and Neptune. A fourth vessel was planned, but a collapse of international agreements prevented the construction of the last ship. It was just as well, since its eventual replacement, the Thule, proved to be a more capable and much faster vessel. In the 30's and 40's missions to the outer system lasted years. Jupiter was three hundred days away, Neptune about a thousand. The Goddard's mission to Neptune, including the delayed return and rescue necessitated by the failure of its primary reactor, lasted over seven years. Excerpt from The First Century in Space, Janek Trudeau, editor, Lassiter Press, 2070