Professor Bainbridge would like to see a "serious cost-benefit analysis" of proposed manned missions to Luna and Mars. Well, I suppose that's fine, as far as it goes… as long as we keep a really flexible idea of both what potential benefits might be and the value of those benefits.

Madame Premier, I cannot tell you what scientific advances will result from the deep space expedition. If I could, there would be no need for us to go on the voyage at all. I could speculate. So could anyone with a minimal level of scientific literacy. But speculation is a game. The history of humanity is a record of explorations intended for one purpose that have completely different effects. People didn't walk east across the Bering land bridge, or sail west across the Atlantic, because they expected to find North America. We didn't go to Mars expecting to break through to superconducting bio-electronics.

Vonda N. McIntyre, Starfarers (1989) at 24 (speech tags omitted for clarity).