NASA 其實我們沒有在火星上發現水
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淌而留下的痕跡，又一次將“火星上是不是有生命存在”這一問題拋了出來。
The findings are the strongest evidence yet that liquid water darkens the Martian surface today; we've known for years that water flowed on Mars long ago。
如今，這一發現是證明液態水使火星表面變得暗沉的最有利證據。其實，多年前我們就知道，很久以前火星上是有水存在的。
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。
《自然地球科學》星期一發布的文章中稱，這一發現表明這些水跡的出現是季節性的，水沿着陡峭的火星山壁一瀉而下，形成了許多深色的水流線條。但是科學家還是不知道水源在哪，或這一化學物是否能夠維持生命。
For now, the find solves the mystery of dark streaks that appear and disappear seasonally, called recurring slope lineae。
目前，這一發現解釋了爲什麼火星表面總會季節性出現或消失深色線紋，這種線段的學名叫做“季節性斜坡紋線”。
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，一位亞利桑那大學的學生——盧金德拉·歐嘉首次發現了這種深色線紋。他一直在研究從裝在美國國家航空暨太空總署火星偵察衛星上的照相機發回地球的照片。歐嘉說，那時候的他一點都不知道這個發現有這麼重要。
Is Mars Sweating?
火星是流汗了嗎？
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。
問題在於水源：這些水從哪裏來？一種可能是由含水層滲透、或地下冰融化造成的。這些現象導致火星“流汗”——由於星球變暖，地下的鹽水從地表空隙滲透出來，並沿着表面斜坡流淌下來。
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。
水也有可能是來源於大氣，這一說法也有人認可。這種假設是說，火星表面鹽分吸取了大氣中的水蒸氣。
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。
目前爲止，能證明火星表面有流動的水存在的證據還是微不足道的。也就是說，在星球探索中，地球外的生命研究還仍只是一個謎。
