NASA's decline in basic research, due to budgetary woes.
It's always hard finding money for science. NASA usually seems to garner some bipartisan support, but the money is always a little below what is needed to really get things moving.
More generally, what really frustrates me are the budget hawks (like Senator John McCain, for instance... though there are certainly others) who delight in finding some obscure, crazy-sounding science project earmark to ridicule for political gain. It's irritating because science is a vast ocean of knowledge, slowly accumulated over the ages through small breakthroughs and painstaking work... the kind of work these scientists are usually doing. Of course debating the merits of a science project up for federal funds is legitimate, but the rhetoric often takes on that same old anti-intellectual tone, and lends credence to the notion that science is just the domain of ivory tower liberals who want to spend all of your money.
If we look at any of the major technical achievements of the 20th century, we can easily see that their development was only made possible by countless earlier discoveries. Television, for example, would not have been possible without first figuring out how to harness electricity, and manipulate radio waves. But the pioneers in those fields could not have had more than a dim notion that something like a television might be possible in the future. And such is the nature of today's discoveries. We can't possibly know what will be developed in the next 10, or 100 years. But they may very well rely on some silly-sounding experiment going on right now.
I wonder what Senator McCain would have said about Gregor Mendel, with those crazy experiments on pea plants. What's that got to do with us?!