“土卫六”表面的流体（图）  

土星卫星“土卫六”被烟雾笼罩。研究人员在其表面上发现了一个象镜面一般平静的湖泊，其中包含乙烷。

Liquid Flowing on Surface of Titan

Saturn's moon Titan has large lakes of liquid, say scientists, making it only the second body in the solar system after Earth to have fluid on its surface.	科学家们称，土星的卫星——“土卫六”拥有大片大片的液体，除地球之外，成为太阳系内唯一拥有表面流体的天体。
Scientists from NASA say the discovery was made after analysis of instruments on the US-European Cassini-Huygens probe, the spacecraft that has been orbiting Saturn since 2004 following a 3.5 billion-kilometre voyage.	自从2004年以来，美国和欧洲联合制造的太空船——“卡西尼-惠更斯”号探测器一直在轨道上围绕着土星飞行，航程达35亿公里。美国国家航空航天管理局的科学家们说，对该探测器上的仪器所获资料进行分析之后，做出了上述发现。
Information from Cassini indicates that large lakes on Titan contain liquid hydrocarbons and ethane, says NASA.	美国国家航空航天管理局宣布，来自“卡西尼”号的信息表明：“土卫六”上的大片湖泊中包含液态碳氢化合物和液态乙烷。
"This is the first observation that really pins down that Titan has a surface lake filled with liquid," says University of Arizona scientist Dr Bob Brown, team leader of Cassini's visual and mapping instrument.	“真正地通过观察来确定‘土卫六’表面上的湖泊里充满着流体，这尚属首次，”亚利桑那大学的科学家鲍勃·布朗博士说。布朗博士是“卡西尼”号太空船视频及测绘仪研究小组组长。
NASA says large dark areas on Titan's surface were spotted during numerous close flybys of the moon. But until now it had not been possible to determine whether they were liquid or solids.	美国国家航空航天管理局称，通过多次近距离飞临“土卫六”，发现其表面拥有大片大片的黑暗区域。可是直到目前才能够确定黑暗区域呈液态还是呈固态。
It says scientists were able to conclude the areas were liquid after studying data from a Cassini instrument able to distinguish chemically different materials based on the way they absorb and reflect infrared light.	据说，“卡西尼”号上的一台仪器根据对红外现的吸收及反射情况，可以从化学的角度区分不同的物质材料。研究了来自这台仪器的资料后，科学家们能够得出结论：黑暗区域呈液态。
The visual and mapping instrument spotted a lake, Ontario Lacus, in Titan's south polar region during a flyby in December, NASA says. The lake is over 20,000 square kilometres in size.	美国国家航空航天管理局称，12月份的一次飞临期间，在“土卫六”南极地区发现了一个湖泊——安大略月面湖，这个湖泊的面积超过20,000平方公里。
"Detection of liquid ethane confirms a long-held idea that lakes and seas filled with methane and ethane exist on Titan," says Dr Larry Soderblom, a scientist with the US Geological Survey in Flagstaff, Arizona. "The fact we could detect the ethane spectral signatures of the lake even when it was so dimly illuminated, and at a slanted viewing path through Titan's atmosphere, raises expectations for exciting future lake discoveries by our instrument."	“发现液态乙烷证实了一个长期持有的观点：‘土卫六’上存在充满甲烷和乙烷的湖泊及海洋，”亚利桑那州旗杆市美国地质调查局的科学家拉里·索德布罗姆说，“事实上，尽管湖光暗淡，并且以倾斜的可视路线穿过‘土卫六’的大气，我们仍然可以探测出湖泊中乙烷的光谱信号。这使我们更有希望在未来利用我们自己的仪器发现令人兴奋的湖泊。”
Scientists ruled out the presence of water ice, ammonia, ammonia hydrate and carbon dioxide in Ontario Lacus.	科学家们排除了安大略月面湖中存在水冰、氨、氨水和二氧化碳的可能性。
The observations also suggest the lake is evaporating. It is ringed by a dark beach, where the black lake merges with the bright shoreline.	观察还表明，这个湖泊正在蒸发。它周围是深暗色的海滩，海滩是黑暗湖泊与明亮海岸线的交汇处。
Launched in 1997, the Cassini-Huygens mission is the first devoted to the exploration of Saturn, and is a joint mission by NASA and the European Space Agency.	1997年发起的“卡西尼-惠更斯”号航天行动是第一个致力于探索土星的行动，而且是美国国家航空航天管理局与欧洲航天局联合发起的行动。