The space program was a lot of fun when I was a kid in the 1960s, but it turned out we were all dressed up in our spacesuits with no particular place to go. The rest of the solar system just isn't very habitable. Venus isn't like the Congo and Mars isn't like Bolivia, the way Heinlein hoped they would be back in the 1950s.

Various Presidents have enunciated various space program goals in recent decades, but not much gets done because it's hard to figure out why we want to spend vast amounts of money to go there.

So, here's a space program goal where we are currently making progress and could actually accomplish within a few decades:

Discover human-habitable planets around other stars.

I'm not at all saying that we should go to these other planets. We can leave that insanely expensive project for future centuries. But finding destinations would keep alive the grandest dream of the human race: to spread out across the galaxy. Personally, I would like to die knowing that my species' fate isn't forever tied to just one planet.