A lot has been made of NASA's on-again, off-again plans for returning people to the Moon and then sending the first human to Mars. Personally, I'm not a big fan of human space exploration right now. Sure, given limitless resources it would be awesome to see a human stepping onto the Red Planet, or to see oxygen-filled domes on the surface of the Moon. But we're not in that position right now.
NASA has done us more good in the last 50 years than most other government agencies. Scientific advances, cultural significance...NASA is undoubtedly essential to our country and to the world. Yet every year they're asked to do more with less. "Do this thing no one else has ever done before, and do it for less money than last year," the federal government says. Then the Pentagon gets another twelve billion dollars no questions asked.
Given NASA's budget restrictions, it shouldn't be focused on people. It should be focused on increasingly ambitious landers and satellites. Two obvious candidates are the moons of Jupiter and Saturn. Here's why: the Moon is a barren rock. We established that long ago. It's got some ice, but so does Antarctica. Mars is totally awesome, but it too is a barren rock. It's got some ice and may even have water under its sandy surface. But so what? That's basically a bigger Moon.
Jupiter's moon Europa and Saturn's moon Titan both have giant oceans. Real liquid. They may have real life forms living in those oceans, right this second. Europa's ocean is underneath a layer of ice, but it may be heated by thermal vents coming up from the planet's core. We've already found life on our sea floor living near thermal vents, so it wouldn't be such a jump that life could exist elsewhere in the Solar System in the same way. Titan is even better: it's got oceans right there on the surface. Isn't all that a bigger deal than digging for ice on Mars?
Fortunately, there are plans for sending probes to both Europa and Titan in the coming decades. There will be an orbiter for Europa which will scan the surface. Titan may get a twofer: a hot air balloon that will fly through its atmosphere as well as a lander that will ride the waves of Titan's seas. I can't wait until the 2030's when these two projects will be sending back information to Earth.
In the meantime, though, if NASA is forced to spend the majority of its limited resources on manned missions to barren worlds, we won't see as many exciting projects like the ones discussed above. I mean, there are lots of rocks out there. Why don't we try for as many as possible?