| A spacecraft orbiting Mars has scanned huge deposits of water ice at its south pole so plentiful they would blanket the planet in 11 metres of water if they were liquid, scientists say. |
科学家们说一艘绕火星飞行的太空船发现：火星的南极覆盖着大片的冰层，蓄水量非常丰富，假如呈液态，整个火星将会被11米深的水所覆盖。 |
| They used a joint NASA-Italian Space Agency radar instrument on the European Space Agency Mars Express spacecraft to gauge the thickness and volume of ice deposits at the Martian south pole. The deposits, up to 3.7 kilometres thick, are under a polar cap of white frozen carbon dioxide and water, and appear to be composed of at least 90% frozen water, with dust mixed in, according to findings published in the journal Science. |
科学家们利用欧洲航天局“火星快车”号太空船上的雷达装置测量出火星南极冰层的厚度和体积。该雷达装置是美国国家航空航天局和意大利航天局联合制造的。根据发表《科学》杂志上的数据，在冻结的白色二氧化碳和水构成的极冠下，覆盖着厚达3.7公里的冰层，好象至少90%是由固态水构成，其中还混杂着尘埃。 |
| Scientists have known that water exists in frozen form at the Martian poles, but this research produced the most accurate measurements of just how much there is.They are eager to learn about the history of water on Mars because water is fundamental to the question of whether the planet has ever harboured microbial or some other life. |
科学家们已经了解到水以固态的形式存在于火星的两极，而这项研究最准确地测量出到底有多少水。科学家们渴望了解火星水的历史，因为水是最根本的，决定了该行星上是否曾经生活着微生物或其他形态的生命。 |
| Characteristics like channels on the Martian surface strongly suggest the planet once was very wet, a contrast to its present arid, dusty condition. |
火星表面的沟槽特征有力地说明了该行星一度非常湿润，与目前干旱的、布满尘埃的状况截然不同。 |
| Dr Jeffrey Plaut of NASA's Jet Propulsion Laboratory in Pasadena, California, who led the study, says the same techniques are being used to examine similar ice deposits at the Martian north pole. |
美国国家航空航天局喷气动力实验室的杰弗里·普劳特博士主持了该项研究。他说，同样的技术正在用于测定火星北极类似的冰层。 |
| Radar observations made in late 2005 and early 2006 provided the data on the south pole, and similar observations were taken of the north pole in the past several months, Plaut says. |
普劳特说，2005年底和2006年初的雷达观测提供了有关火星南极的数据资料，在过去的几个月里对其北极也进行了同样的观测。 |
| Plaut, part of an international team of two dozen scientists, says a preliminary look at this data indicates the ice deposits at the north pole are comparable to those at the south pole. |
普劳特是一个跨国科研小组中的24位科学家之一。他说，对数据资料的初步观察显示：火星北极的冰层不亚于南极。 |
| Search for life |
寻找生命 |
| "Life as we know it requires water and, in fact, at least transient liquid water for cells to survive and reproduce. So if we are expecting to find existing life on Mars we need to go to a location where water is available," Plaut says. "So the polar regions are naturally a target because we certainly know that there's plenty of [water] there." |
“众所周知，生命需要水。事实上，至少要有短期存在的液态水，细胞才能存活和繁殖。所以如果期望火星上存在生命，我们就需要探测有水的地方，”普劳特说，“火星的两极地区自然成为我们的探测目标，因为我们确切地了解那里存在丰富的水源。” |
| Some of the new information even hints at the possible existence of a thin layer of liquid water at the base of the deposits. |
一些新资料提供的线索表明，在这些冰层的底部有可能存在薄薄一层液态水。 |
| While images taken by NASA's Mars Global Surveyor spacecraft made public in December suggest the presence of a small amount of liquid water on the surface, researchers are baffled about the fate of most of the water. |
美国国家航空航天局的“火星环球探测者”太空船拍下的图片显示，火星的表面存在少量的液态水，但研究人员对其中大部分水的去向感到迷惑不解。 |
| The polar deposits contain most of the known water on Mars. |
极地的冰层储存着火星上绝大部分已知水源。 |
| Plaut says the amount of water in the Martian past may have been the equivalent of a global layer hundreds of metres deep, while the polar deposits represent a layer of perhaps tens of metres.“We have this continuing question facing us in studies of Mars, which is: where did all the water go?" Plaut says. "Even if you took the water in these two [polar] ice caps and added it all up, it's still not nearly enough to do all of the work that we've seen that the water has done across the surface of Mars in its history." |
普劳特指出，过去火星上的水量相当于覆盖全球几百米深的水层，而极地的冰层显示的水量大概不过几十米深的水层。 “在对火星的研究中，我们一直面临的问题就是：所有的水究竟去往何处？”普劳特说，“即使将两极冰冠中的水加在一起，仍不足以造成我们所看到的火星地貌。” |
| Plaut says it appears perhaps 10% of the water that once existed on Mars is now trapped in these polar deposits.Other water may exist below the planet's surface or perhaps some was lost into space through the atmosphere, Plaut says. |
普劳特说，看来在火星以往的水量中，仅有约10%集中在现在的两极冰层中；其余的水或许现存于火星地表下，或许有些已经通过大气散失于太空之中。 |
