It's not that they don't want to or that they aren't putting enough effort into it. It's that they're drastically underfunded. They receive far less money than any other government organization, and the government expects them to work on so many projects at once that they can't really get everything done that they want to. For example, Bush told NASA that he wants to see a man on the moon again and a man on Mars, but didn't provide them with any extra money to get that done, so they've had to cut current projects to start working on that. It's really sad, actually. We're wasting so much money building the largest military in the world into an even larger military so we can more efficiently battle other countries, when we could be investing in our species' common future in outer space.