经济学人下载:太空时代的结束

Space exploration
太空探索

The end of the Space Age
太空时代的结束

Inner space is useful. Outer space is history
研究内太空才有用，让外太空研究成为历史

Jun 30th 2011 | from the print edition

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.

地球有多大？任何一本百科全书都会给你答案：赤道直径是12,756公里，或者，用英里来表达7,926英里。嗯，但是大气层有多大呢？也能计算吗? 包括空气（大气层）在内，地球的直径可能接近13,000公里。甚至连这个数据也不够充分。因为现在地球的变化太大（远离平静的状态）。包围大气层的外部空间人造卫星来去匆匆，形成一个在大气层外面的所谓技术层。大部分卫星绕行高度离地球地表仅几百公里。然而，在距地球36,000公里的轨道上物体绕转地球一周的时间为24小时，这个物体飞行时持续面对的是地球上的不变的同一个点，这样许多地球同步卫星的运行会形成一个类似的土星环。

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.

从这个方面看，地球比传统的教科书上的回答其实要大很多。这样看来，太空时代已经有了相当的成功。电信业，天气预测，农业，林业，甚至是在矿藏搜寻方面都有了彻底变革。战争也同样如此，再也没有政府能秘密地调兵遣将。这颗星球上的每一幢建筑物的位置都能被精确掌握。基于卫星的全球定位系统能按要求指引智能炸弹到达目标。