Scientists say they have found the most detailed evidence yet of long-flowing, ancient rivers on Mars.
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。
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 camerais able totake 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 objectcrashes intoa 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.
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。
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.
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。”
"OK, it is not like reading a newspaper, but the extremely high resolution imageryallowedusto'read' the rocksas ifyou 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 beforebeen able toexamine 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.