I sent an armada of ships to Duna to start a space station. There were six: a probe carrier, the main station, a tanker, a miscellaneous parts carrier (with various science, power, docking adapters and Kethane refining equipment), a manned Kethane mining craft and a Duna lander. Of the six ships, only three made it. The miner, lander and misc ship didn't make it - all Kerbals were lost. The ships either got tossed out of solar orbit at ludicrous speeds or exploded suddenly. Now I've got a fully fueled and equipped station with a probe network silently orbiting Duna, sitting lonely with no crew. I think I'll stick to sending single large ships on interstellar missions.