Travel to other planets is such a practical scientific impossibility that nasa is completely irrelevant. Saying that traveling to the moon is a first step to interplanetary travel is about like saying that traveling to the top of mount Everest is an important first step to the moon. If you want to get to the moon, you need to build rockets; climbing mountains is a distraction; you can't climb to the moon no matter how good of a climber you are. If you want to get to another planet, well, I think you are going to need hyperspace or wormholes or other physics that don't really exist yet, in which case your breakthrough is going to come in a chalk room or physics laboratory, and prancing around on regolith is a similar distraction.
People think technology is magic, so if we can go from the pony express to cell phones in a couple hundred years, it will only be a matter of time until we have one of those fancy space ships they saw on TV. But technology will never invent a perpetual motion machine or a single-reservoir heat engine and it's NOT a matter of time or a matter of wanting it bad enough. And any exoplanets, supposing there are any, are so far away as to be irrelevant. They are far. Like really far. Like so far that when we find one, we won't even know if it's there because the light will be centuries old by the time it hits our telescopes. Using the possibility of interstellar travel to justify NASA funding is basically a joke. Oh, it sounds romantic though.