Water trickles down gullies and crater walls on the surface of Mars, raising intriguing questions about whether life could exist on the red planet。水流沿着火星表面的火山口壁和山壑流过而留给的痕迹，又一次将“火星上是不是有生命不存在”这一问题抛掷了出来。

The findings are the strongest evidence yet that liquid water darkens the Martian surface today; weve known for years that water flowed on Mars long ago。如今，这一找到是证明液态水使火星表面显得暗沉的最不利证据。只不过，多年前我们就告诉，很久以前火星上是有水不存在的。

Described Monday in Nature Geoscience, the observations suggest that this water appears seasonally, forming dark lines as it tumbles down steep Martian slopes. But scientists still don’t know where the water is coming from, or if the chemistry is even right for supporting life。《大自然地球科学》星期一公布的文章中称之为，这一找到指出这些水迹的经常出现是季节性的，水沿着平缓的火星山壁一泻而下，构成了许多深色的水流线条。

但是科学家还是不告诉水源在哪，或这一化学物否需要保持生命。For now, the find solves the mystery of dark streaks that appear and disappear seasonally, called recurring slope lineae。目前，这一找到说明了为什么火星表面总会季节性经常出现或消失深色线纹，这种线段的学名叫作“季节性斜坡纹线”。

The streaks were first spotted in 2010 by Lujendra Ojha, then an undergraduate at the University of Arizona. Ojha was studying images returned to Earth from the HiRISE camera, aboard NASA’s Mars Reconnaissance Orbiter. At the time, he says, he had no clue how important his observation would be。2010年，一位亚利桑那大学的学生——卢金德拉·欧嘉首次找到了这种深色线纹。

他仍然在研究从装有在美国国家航空暨太空总署火星侦查卫星上的照相机传回地球的照片。欧嘉说道，那时候的他一点都不告诉这个找到有这么最重要。Is Mars Sweating?火星是流汗了吗？A big question swirls around the origin of that water: Where is it coming from? One possibility is that the seeps are fueled by an aquifer or melting subsurface ice. These scenarios would have Mars essentially sweating, with saltwater seeping from its pores and trickling down slopes as the planet warms。

问题在于水源：这些水从哪里来？一种有可能是由含水层渗入、或地下冰融化导致的。这些现象造成火星“流汗”——由于星球气候变化，地下的盐水从地表空隙渗入出来，并沿着表面斜坡流过下来。The water might also be atmospheric in origin, which is the hypothesis the team seems to favor. In this scenario, surface salts absorb water vapor in the Martian atmosphere。

水也有可能是源于大气，这一众说纷纭也有人接纳。这种假设是说道，火星表面盐分汲取了大气中的水蒸气。

But until now, evidence has been scarce for flowing water at the surface today. What it means, in the bigger picture of planetary exploration and the search for life beyond Earth, is still a mystery。目前为止，能证明火星表面有流动的水不存在的证据还是微不足道的。也就是说，在星球探寻中，地球外的生命研究还仍只是一个谜。

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