Titan, one of Saturn's moons, has an underground ocean

... and here is how we get there, similar to how Bill Stone proposes we get to Jupiter's moon Europa: http://www.youtube.com/watch?v=-Bn6Gel7yEs#t=6m9s

In case anyone's counting, this makes it the 5th planetary body in the solar system with a high likelihood of having an ocean (Earth, Europa, Ganymede, Callisto, and now Titan).

Add to that a parcel of additional moons and other other bodies that show indications of having sub-surface oceans (Triton, Enceladus, Pluto, Rhea, Titania, Eris, Sedna, Orcus, and Oberon).

It's not really an "ocean" in the way we think of such things. In the outer solar system, ice is a rock in the same way granite is a rock. What Titan has isn't so much an ocean as an interior layer of molten ice --- just as our planet has an interior layer of molten rock.

Please, can we now put a reasonable nuclear reactor in space, power a VASIMIR engine (or something equally adequate), and do it with humans instead of robots? We already proved we can do it with machines and who will make first contact with alien life in becoming a really important question. We are not a race of robots.

People wonder why the general public lost interest with space exploration, but we need to look no further than all the excitement every six-wheeler is experiencing right now, as they watch their six-wheeled brothers, the daring explorers of Mars.

I am an engineer. I can comprehend and I do have the ultimate respect for the genius that allows us to land and operate robots on Mars, but that's the same genius that allowed us to land people on the Moon and, sadly, this is something we don't do anymore because it's too expensive. And we refuse to spend money on that while, at the same time, we fight unnecessary wars against the dictators we financed in the past. There is water ice on the Moon, probably a lot of it. There are minerals, abundant energy, just enough gravity to make industrial processes easy and a high grade vacuum that's the dream of every metallurgist. With these resources, we can become a true spacefaring civilization fit to meet our neighbors from the other islands floating around our sun.

We shouldn't do with robots the work of humans.

A lot of the Rocket to Nowhere arguments address your points: http://idlewords.com/2005/08/a_rocket_to_nowhere.htm

In short, as soon as large hairless mammals are involved in the mission, 99% of the mission's resources are suddenly consumed with keeping said large hairless mammals fed, watered, breathing, amused, etc. So basically, there's nothing left to do anything of much value, especially on any kind of reasonable budget.

Cost is the main reason robots have gone all over the Solar System and beyond, and the farthest any humans go these days is to LEO to hang out at the ISS.