大众英语80篇背诵阅读带翻译(三十八)
"76 MARS
Mars According to the best evidence gathered by space probes and astronomers, Mars is an inhospitable planet, more similar to Earth's Moon than to Earth itself - a dry, stark, seemingly lifeless world. Mars' air pressure is equal to Earth's at an altitude of 100,000 feet. The air there is 95百分 carbon dioxide. Mars has no ozone layer to screen out the Sun's lethal radiation. Daytime temperatures may reach above freezing, but because the planet is blanketed by the mere wisp of an atmosphere, the heat radiates back into space. Even at the equator, the temperature drops to 50℃ ( 60 ) at night. Today there is no liquid water, although valleys and channels on the suITce show evidence of having been carved by running water. The polar ice caps are made of frozen water and carbon dioxide, and water may be frozen in the ground as permafrost. Despite these difficult conditions, certain scientists believe that there is a possibility of transforming Mars into a more Earth like planet. Nuclear reactors might be used to melt frozen gases and eventually build up the atmosphere. This in turn could create a "greenhouse effect" that would stop heat from radiating back into space. Liquid water could be thawed to form a polar ocean. Once enough ice has melted, suitable plants could be introduced to build up the level of oxygen in the atmosphere so that, in time, the planet would support animal life from Earth and even permanent human colonies. "This was once thought to be so far in the future as to be irrelevant," said Christopher McKay, a research scientist at the National Aeronautics and Space Administration. "But now it's starting to look practical. We could begin work in four or five decades." The idea of "terra forming" Mars, as enthusiasts call it, has its roots in science fiction. But as researchers develop a more profound understanding of how Earth's ecology supports life, they have begun to see how it may be possible to create similar conditions on Mars. Don't plan on homesteading on Mars any time soon, though. The process could take hundreds or even thousands of years to complete, and the cost would be staggering.火星据宇宙探测器和地理学家搜集的无力证据，火星是一团体类不能栖身的星球。它不像地球，而更像月球--一个干枯、荒芜，看上往没有任何生命的世界。火星的气压相称于地球上十万英尺空中处的气压。火星年夜气的组成中有 95百分是二氧化碳，并且，火星上没有能屏障太阳致命射线的臭氧层。白天，那边的温度可以到达零上，但因为包裹火星的年夜气层极为淡漠，热量又会辐射回宇宙中。就算是在火星赤道，夜里的温度也在 50℃。虽然火星上的山谷沟渠申明它已经被流水蚀刻过，但现在那边已没有液态水了。极地冰帽是由固态水和二氧化碳组成的，水也有年夜概存在于永久冻土之中。虽然困难重重，某些迷信家仍然以为有年夜概把火星改形成类似地球的星球。核反响反应可以用来消融冰冻的气体最终组成火星年夜气层。由此就可以发作温室效应，防止热量散射回宇宙中。液化的水可以消融成极地陆地。足够量的冰消融后，可将地球上的动物移植上往。动物又可以向年夜气层供给氧气。一朝一夕火星就可以维持从地球过往的动物生命乃至成为人类的永久居留地。 "这一 切在过往看起来远远得近乎无稽"，国家航天局的一位钻研人员，克里斯托弗·麦克凯说，"可是现在已经开始显现出年夜概性。四五十年后，我们就可以动手于这项义务。"这种支撑者们称为"移居火星"的设法最早出现在科幻小说中。但跟着钻研者对地球上生态若何支撑生命的了解越来越深进，在火星上发明类似地球情况也显得越来越理想。但万万别计划很快在火星上制作故里。这个历程需要几百乃至上千年，并且破费将是惊人的。
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