Science!
I am an enthusiastic proponent of manned space flight (Go Project Constellation!), but that does not mean I am not also an enthusiastic proponent of unmanned missions of exploration. After all, Opportunity and Spirit's mission was nicknamed M2K4 meaning "Mars 2004," and the twin rovers were only supposed to survive for three months. But M2K4 has inexorably given way to M2K5, M2K6, M2K7 with no clear end in sight! We must harness the fruits of the greatest minds on Earth and unleash an armada of robots to wrest from nature the secrets of the seas of Europa. Robots of Earth, your destiny is to be found among the stars! Go forth, you magnificent mechanical minions! For Earth! For glory! For science! Science!