A PURELY ROBOTIC SPACE PROGRAM IS WORTHLESS.
In my opinion, the point of a space agency is to arrange things to get humans off Earth. Robotics is acceptable as a means to that end, but it has no right to be an end in itself. To people who say that space exploration is a ridiculous luxury, I say that you have no business subsidizing research for research's sake on the public dime. I'm vociferous about this because, in the end, the equation is simple.
Either we go to space, or we die.
See how simple that is? Eight words that sums it all up, and all the goddamn telemetry in the world won't change the fact that all the money pumped into deep space probes will have been wasted if we just step back from the brink, circle our wagons around this planet, and wait for some asteroid or comet or major solar flare or environmental collapse to finish us. Because one of those will happen. With the right timescale, the certainty of anything approaches totality.
I'm not saying that by going to space we assure our survival as a species - space, you know, is a dangerous place. But that is the only choice that allows for the possibility of our survival being assured. Sooner or later, no matter how well we take care of it, Earth is going to become uninhabitable. I have no interest in the extinction of the human race if this can possibly be avoided - which, thankfully, puts me in a different category than Charles Stross, who believes that the opinion I'm expressing here is "an appeal to sentimentality," because "the future extinction of the human species cannot affect you if you are already dead: strictly speaking, it should be of no personal concern."
I have to wonder if this idea isn't in some way hitching a ride on the modern-day fallacy of economics - the idea that infinite growth is possible in a finite system. We're already running into the failings of that particular philosophy. It's easy for a person to think people can live on Earth indefinitely; I mean, look how BIG it is! These tend to be the sort of people who don't think through the implications of their actions or ideas.
I will close on a clip from the first season of Babylon 5, which sums up what I've been trying to say.
Also, anyone who recognizes where I got the title for this post gets an egoboo.