火星上存在古代河流的新证据（双语文本）

New Evidence Found of Ancient Rivers on Mars
Scientists say they have found the most detailed evidence yet of long-flowing, ancient rivers on Mars.
The discovery supports existing evidence that Mars – which today is dry and cold – was once a water-rich planet. The researchers say their findings suggest rivers may have flowed on the surface of Mars for hundreds of thousands of years.
The evidence came from new satellite pictures of the Martian surface. These images were captured by a camera on NASA's Mars Reconnaissance Orbiter. The camera is able to take detailed pictures of the surface while orbiting the planet from about 400 kilometers away.
A team of scientists studied the images, which showed a rocky area within the planet's Hellas Impact Crater. An impact crater is formed when a space object crashes into a planet or moon. The Hellas Impact Crater, in the southern Martian hemisphere, is one of the largest formations of its kind in the solar system.
The team was led by Francesco Salese, a geologist at Utrecht University in the Netherlands. The research results were recently published in a study in Nature Communications.
Salese said the scientists studied sedimentary rocks from a 200 meter high rocky cliff. Sedimentary rocks form when sediment, transported by water or wind, settles and forms solid rock.
"These are sedimentary rocks, 3.7 billion years old, and were formed by rivers that were likely active for over 100,000 years of Martian history," Salese said in a statement.
"OK, it is not like reading a newspaper, but the extremely high resolution imagery allowed us to 'read' the rocks as if you are standing very close to the cliff," he added.
Salese said even without the ability to examine the cliff area up-close on Mars, the pictures show strong similarities to sedimentary rocks found on Earth.
The researchers created three-dimensional, or 3D, images of the area to get a more detailed understanding of it. The pictures suggested that some ancient Martian rivers were several meters deep.
William McMahon is another geologist who was part of the investigation team. He said sedimentary rocks have long been studied on Earth to learn what conditions were like on our planet millions, or even billions of years ago.
"Now we have the technology to extend this methodology to another terrestrial planet, Mars, which hosts an ancient sedimentary rock record which extends even further back in time than our own," McMahon said in a statement.
Another leader of the team was Joel Davis, a researcher with Britain's Natural History Museum. He said scientists had never before been able to examine such a rock formation with such great detail.
Davis said the discovery is "one more piece of the puzzle in the search for ancient life on Mars." He added that it also provides new evidence of how much water existed on Mars in ancient times.
"The rivers that formed these rocks weren't just a one-off event — they were probably active for tens to hundreds of thousands of years," Davis said.
Salese added that the findings show Mars had an environment able to support large, flowing rivers for extended periods of time.
"This kind of evidence, of a long-lived watery landscape, is crucial in our search for ancient life on the planet," Salese said.
I'm Bryan Lynn.

火星上存在古代河流的新证据
科学家表示，他们发现了迄今为止最详细的证据，证明火星上存在古老河流。
这一发现支持现有证据，证明如今干燥且寒冷的火星曾是富水行星。研究人员表示，他们的发现表明，河流可能在火星表面流淌了数十万年。
证据来自火星表面的最新卫星图像。这些图像由美国国家航空航天局（简称NASA）的火星勘测轨道飞行器搭载的摄像头拍摄。这个摄像头能在距离火星约400公里的轨道上拍下详细的火星表面图像。
一个科学家小组研究了这些图像，图像显示了火星海拉斯撞击坑内的岩石区域。当太空物体撞上行星或月球时，就会形成撞击坑。海拉斯撞击坑位于火星南半球，是太阳系中最大的撞击坑之一。
该小组由荷兰乌得勒支大学的地质学家弗朗西斯科·萨莱斯领导。研究结果于最近发表在《自然通讯》期刊上。
萨莱斯表示，科学家研究了200米高的岩石悬崖上的沉积岩。沉积岩指沉积物经水或风的搬运通过沉淀形成的固体岩石。
萨莱斯在声明中表示，“这些是37亿年前的岩石，由可能在火星历史上活跃了10万多年的河流形成。”
他补充表示，“这不像看报纸，但极高清图像使我们得以‘看到’岩石，就好像我们站在距离悬崖非常近的地方。”
萨莱斯表示，即使不具备近距离观察火星悬崖区域的能力，但这些图像表明，火星上的沉积岩与地球上发现的沉积岩极为相似。
研究人员创建了该地区的三维图像（3D），以便对其有更详细的了解。这些图像表明，火星上一些古代河流有数米深。
威廉·麦克马洪是该调查小组中的另一名地质学家。他说，长期以来，人们一直在研究地球上的沉积岩，以了解数百万甚至是数十亿年前地球的状况。
麦克马洪在声明中表示，“现在我们拥有了将这种方法扩大到另一个类地行星——火星——的技术，火星上保存着一份古老的沉积岩记录，其时间甚至比我们地球的记录还要久远。”
研究小组的另一名领导者是英国自然历史博物馆的研究员乔尔·戴维斯。他表示，科学家以前从未能如此详细地研究这种岩层。
戴维斯表示，这一发现“是在探索火星古代生命进程中遇到的又一个谜团”。他还表示，这也为古代火星上存在多少水提供了新证据。
戴维斯说：“形成这些岩石的河流不只是一次性事件，它们可能活跃了几万到几十万年。”
萨莱斯补充说，研究结果表明，火星拥有能长期维持大型河流流动的环境。
萨莱斯说：“证明存在长期水景的这种证据，对我们在火星上寻找古代生命至关重要。”
布莱恩·林恩报道。