OPINION: Watch on the Earth

Somebody is always rising to announce that mankind has arrived at a dead end, or at least a stop light. In the October issue of Harper's, a new warning voice rolls out, announcing that civilization's "400-year boom" is over because civilized nations have no more geographical frontiers to push back. The voice comes, oddly enough, from Texas. It belongs to Professor Walter Prescott Webb, a thoughtful student of history.

In Manhattan, some 300 scientists, doctors, astronomers, engineers, aviators and lawyers were too busy to hear it. They were gathered at the Hayden Planetarium for the first annual Symposium on Space...