HOW big is the Earth? Any encyclopedia will give you an answer: its equatorial diameter is 12,756km, or, for those who prefer to think that way, 7,926 miles. Ah, but then there is the atmosphere. Should that count? Perhaps the planet’s true diameter is actually nearer 13,000km, including all its air. But even that may no longer be an adequate measure. For the Earth now reaches farther still. The vacuum surrounding it buzzes with artificial satellites, forming a sort of technosphere beyond the atmosphere. Most of these satellites circle only a few hundred kilometres above the planet’s solid surface. Many, though, form a ring like Saturn’s at a distance of 36,000km, the place at which an object takes 24 hours to orbit the Earth and thus hovers continuously over the same point of the planet.
Viewed this way, the Earth is quite a lot larger than the traditional textbook answer. And viewed this way, the Space Age has been a roaring success. Telecommunications, weather forecasting, agriculture, forestry and even the search for minerals have all been revolutionised. So has warfare. No power can any longer mobilise its armed forces in secret. The exact location of every building on the planet can be known. And satellite-based global-positioning systems will guide a smart bomb to that location on demand.
Yet none of this was the Space Age as envisaged by the enthusiastic “space cadets” who got the whole thing going. Though engineers like Wernher von Braun, who built the rockets for both Germany’s second-world-war V2 project and America’s cold-war Apollo project, sold their souls to the military establishment in order to pursue their dreams of space travel by the only means then available, most of them had their eyes on a higher prize. “First Men to a Geostationary Orbit” does not have quite the same ring as “First Men to the Moon”, a book von Braun wrote in 1958. The vision being sold in the 1950s and 1960s, when the early space rockets were flying, was of adventure and exploration. The facts of the American space project and its Soviet counterpart elided seamlessly into the fantasy of “Star Trek” and “2001: A Space Odyssey”. Other planets may or may not have been inhabited by aliens, but they, and even other stars, were there for the taking. That the taking would begin in the lifetimes of people then alive was widely assumed to be true.
No longer. It is quite conceivable that 36,000km will prove the limit of human ambition. It is equally conceivable that the fantasy-made-reality of human space flight will return to fantasy. It is likely that the Space Age is over.