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% 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 surface 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.

 火星據宇宙探測器和天文學家收集的有力證據，火星是一個人類不能居住的星球。  它 不像地球，而更像月球--一個干涸、荒蕪，看上去沒有任何生命的世界。

 火星的氣壓相當 于地球上十萬英尺高空處的氣壓。  火星大氣的構成中有 95%是二氧化碳，而且，火星上沒 有能屏蔽太陽致命射線的臭氧層。

 白天，那里的溫度可以達到零上，但因為包裹火星的大 氣層極為稀薄，熱量又會輻射回宇宙中。就算是在火星赤道，夜里的溫度也在         50℃。  盡

 管火星上的山谷溝渠說明它曾經被流水蝕刻過，但如今那里已沒有液態水了。  極地冰帽是 由固態水和二氧化碳組成的，水也有可能存在于永久凍土之中。

 盡管困難重重，某些科學 家依然認為有可能把火星改造成類似地球的星球。  核反應可以用來融化冰凍的氣體最終形

 成火星大氣層。由此就可以產生溫室效應，阻止熱量散射回宇宙中。  液化的水可以融化成 極地海洋。 足夠量的冰融化后，可將地球上的植物移植上去。

 植物又可以向大氣層提供氧 氣。  久而久之火星就可以維持從地球過去的動物生命甚至成為人類的永久居留地。  "這一

 切在過去看起來遙遠得近乎無稽"，國家航天局的一位研究人員，克里斯托弗·麥克凱說，" 但是現在已經開始展現出可能性。

 四五十年后，我們就可以著手于這項工作。"這種支持者 們稱為"移居火星"的想法最早出現在科幻小說中。  但隨著研究者對地球上生態如何支持生

 命的理解越來越深入，在火星上創造類似地球環境也顯得越來越現實。  但千萬別計劃很快 在火星上建造家園。

這個歷程需要幾百乃至上千年，而且耗費將是驚人的。

譯路通武漢江漢區翻譯公司整理

2012.6.22