" The whole question of using the planets for something—something, that is, besides research—ought to be within sight of settlement. Instead, nobody even discusses it any more. And our chances to settle it grow worse every year. Our appropriations are dwindling, as it gets harder and harder to convince the Congress that space flight is really good for anything. You can’t sell the Congress on the long-range rewards of basic research, anyhow; representatives have to stand for election every two years, senators every six years; that’s just about as far ahead as most of them are prepared to look. And suppose we tried to explain to them the basic research we’re doing? We couldn’t; it’s classified! “And above all, Seppi—this may be only my personal ignorance speaking, but if so, I’m stuck with it—above all, I think that by now we ought to have some slight clue toward an interstellar drive. We ought even to have a model, no matter how crude—as crude as a Fourth of July rocket compared to a Coupling engine, but with the principle visible. But we don’t. As a matter of fact, we’ve written off the stars. Nobody I can talk to thinks we’ll ever reach them. "

― James Blish , Cities in Flight (Cities in Flight, #1-4)