shrouded in the iconic pink haze, this awe-inspiring image is believed to be definitive evidence that the red planet had a watery past.
the pictures, taken by nasa's mars reconnaissance orbiter, reveal a 30-mile-long (50-kilometer-long) canyon where researchers believe water once flowed at the bottom of a basin surrounded by telltale remnants of beach.
dubbed the shalbatana lake after the much larger valley in which it is located, scientists believe it is as large as lake champlain, the mass of water that borders the united states and canada, and could hold critical evidence of past life.
lead researcher gaetano di achille of the university of colorado at boulder said: 'this is the first unambiguous evidence of shorelines on the surface of mars.
'the identification of the shorelines and accompanying geological evidence allows us to calculate the size and volume of the lake, which appears to have formed about 3.4billion years ago.
the team constructed the ancient concept from images taken by a high-powered camera known as the high resolution imaging science experiment, or hirise, riding on the back of nasa's mars reconnaissance orbiter.
the hirise can resolve features on the surface down to just a metre (3.3 feet) in size from its orbit 200 miles (322 kilometres), about the distance from brighton to york, above mars.
an analysis of the hirise images indicates that water carved a 30-mile-long canyon that opened up into a valley, depositing sediment into a large delta, the researchers say.
di achille said the pristine lakebed and delta deposits revealed in the provocative image would be prime targets for a future landing mission to mars.
'on earth, deltas and lakes are excellent collectors and preservers of signs of past life,' said di achille.
'if life ever arose on mars, deltas may be the key to unlocking mars' biological past.'
the new evidence, which suggests the lake formed 3.4billion years ago, challenges a widely held belief about the planet’s evolution.
planetary scientists generally accept that the oldest surfaces on mars formed during the wet and warm noachan epoch, which featured a bombardment of large meteors and extensive flooding, from about 4.1billion to 3.7billion years ago.
but the university of colorado team says the lake formed during the hesperian epoch, postdating the end of the warm and wet period on mars by 300million years.
co-researcher, assistant professor brian hynek said: ‘not only does this research prove there was a long-lived lake system on mars, but we can see that the lake formed after the warm, wet period is thought to have dissipated.'
mars expert jim bell from cornell university expressed reservations about the findings, published in this week's geophysical research letters.
the professor in the department of astronomy at cornell university in ithaca, new york, said the water probably evaporated or froze over.
he said he would like to see other data besides images to support the claim that there was actually a lake.
据英国《每日邮报》6月20日报道，这个令人惊叹的图像隐藏在粉红色的薄雾中，据信，该图像提供了确切证据，可以证明这个红色星球上过去曾经溪水潺潺。
美国国家宇航局火星勘测轨道飞行器在火星表面拍摄到一个30英里长的峡谷，研究人员相信峡谷底部曾有水流过，因为图像显示峡谷底部周围有海滩的残余物。由于图像中的峡谷位于众多山谷中，科学家把这个地方称为沙尔巴塔纳湖。科学家相信，沙尔巴塔纳湖和位于美国和加拿大边境的夏普伦湖一样大，沙尔巴塔纳湖的存在可以证明过去这里曾经有生命的迹象。
科罗拉多大学波尔多分校的盖塔诺·迪亚克雷是这项研究的领导者，他说，“这是能证明火星表面存在湖岸线的第一个确凿证据。湖岸线的鉴定和其它的地质学证据使我们能计算出该湖的面积和容量，这个湖大约形成于34亿年前。”
研究小组根据美国国家宇航局火星勘测轨道飞行器上的“高清晰度科学实验成像” 照相机拍摄的图片模拟一个火星古代湖泊。“高清晰度科学实验成像”能够从距火星322公里的轨道上拍摄到火星表面1米大小的物质特征。
研究人员对“高清晰度科学实验成像”拍摄到的图象进行了分析，结果表明，水流冲刷出一个30英里长的峡谷，该峡谷与一个山谷相连，流水沉淀物形成了一个巨大的三角洲。
迪亚克雷称，图象中显示的原始湖床和三角洲沉淀物将成为人类未来火星着陆任务的主要研究目标。迪亚克雷说，“地球上的三角洲和湖泊很好地‘收藏了’并保存了过去生命的迹象。如果火星上曾出现过生命，那么三角洲可能是破解火星生物学历史的关键所在。”
火星湖岸线的最新证据向人们普遍认为的火星演变过程发起了挑战。通常行星科学家们认为，火星上最古老的表面是在潮湿、温暖的诺亚坎时期形成的，诺亚坎时期距今41亿年到37亿年，那时火星曾遭遇巨大流星撞击，并伴有大范围的洪水泛滥。但科罗拉多大学研究小组称，湖泊形成于西方纪，是火星上温暖潮湿气候结束后形成的。
参与此项研究的副教授布莱恩·海尼克说，“这次研究不仅能够证明火星上有一个持续时间很长的湖泊系统，而且我们还知道在温暖潮湿气候结束后形成的湖泊已经消失得无影无踪。”
这项研究成果已发表在本周的《地球物理学研究通讯》上。康奈尔大学的火星专家吉姆·贝尔对此研究成果持保留态度。位于纽约伊萨卡康奈尔大学天文学系教授认为，火星上的水不是被蒸发掉就是被冻结了。他表示，除了火星图象外，对于火星上确实有湖的说法，他还愿意看到支持这种说法的其它数据。