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New Evidence for Large Ancient Ocean on Mars

时间:2022-11-14 01:17:54

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New Evidence for Large Ancient Ocean on Mars

Researchers say they have discovered new evidence that Mars once had a large northern ocean. The finding adds to existing evidence that ancient Mars had the right conditions to possibly support some form of life.

Today, Mars has a cold, desert climate. Any water is believed to be in the form of ice because of the planet's extremely cold temperatures. But there is a rich amount of evidence suggesting that rivers, lakes and even oceans once existed on Mars.

For example, a 2015 study by the American space agency NASA suggested that 4.3 billion years ago, Mars likely had an ocean that covered nearly half of Mars' northern hemisphere.

Another NASA-supported study, published in January, estimated that three billion years ago, the climate in much of the planet's northern hemisphere was very similar to present day Earth. The study noted1 that at the time, Mars likely had a much thicker atmosphere than today and had an active, northern ocean.

Now, two American researchers have released a set of maps they say provides new environmental evidence of a large ancient ocean on Mars' low-lying northern hemisphere.

The team collected data from satellite images of Mars. They then combined these images to create topography maps of the planet's northern hemisphere.

Using these maps, the researchers said they were able to piece together evidence of shorelines that sat at the edge of a huge body of water about three-and-a-half billion years ago.

The scientists recently published their findings in the Journal of Geophysical Research: Planets.

The team said it used software developed by the United States Geological Survey to map data collected by spacecraft operated by NASA. The research uncovered more than 6,500 kilometers of ridges3 that are believed to have been formed by flowing water.

The scientists say the ridges likely represent the leftover4 evidence of eroded6 river systems and an ancient ocean floor. The team said its research also suggested large levels of sediment7, providing further evidence of a large ocean.

Benjamin Cardenas was a co-writer of the study. He is a professor of geosciences at Penn State University in Pennsylvania. He said in a statement the area of Mars studied – now known as Aeolis Dorsa – contains "the densest8 collection" of water-formed ridges on the planet.

Cardenas said the study's findings demonstrate the possible ocean in that area of Mars was very active and interesting. "It was dynamic. The sea level rose significantly," he said. "Rocks were being deposited along its basins at a fast rate. There was a lot of change happening here."

Cardenas added that areas on our own planet containing water-formed ridges and sediment provide researchers with much useful information about an area's climate and life forms. "If scientists want to find a record of life on Mars, an ocean as big as the one that once covered Aeolis Dorsa would be the most logical place to start," he said.

The team noted that the major goal of NASA's Mars explorer, Curiosity, is to look for signs of ancient life on the planet. Currently, Curiosity is operating within the planet's Gale9 Crater10, which is in the southern hemisphere of Mars. In the past, researchers have also found evidence of past water systems around Gale Crater.

In addition to providing more evidence of a large ocean, Cardenas suggested the new study also provides useful information on Mars' ancient climate and developmental history. "Based on these findings, we know there had to have been a period when it was warm enough and the atmosphere was thick enough to support this much liquid water at one time," he said.

Words in This Story

topography – n. the shape and other physical characteristics of a piece of land

shoreline – n. the edge of a sea, lake or wide river

ridge2 – n. a long, narrow piece of land

erode5 – v. to rub away over time

sediment – n. the material that sinks to the bottom of a liquid

dynamic – adj. continuously changing or developing

deposit – v. to leave something somewhere

logical – adj. reasonable and based on good judgment


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1 noted 5n4zXc     
adj.著名的,知名的
参考例句:
  • The local hotel is noted for its good table.当地的那家酒店以餐食精美而著称。
  • Jim is noted for arriving late for work.吉姆上班迟到出了名。
2 ridge KDvyh     
n.山脊;鼻梁;分水岭
参考例句:
  • We clambered up the hillside to the ridge above.我们沿着山坡费力地爬上了山脊。
  • The infantry were advancing to attack the ridge.步兵部队正在向前挺进攻打山脊。
3 ridges 9198b24606843d31204907681f48436b     
n.脊( ridge的名词复数 );山脊;脊状突起;大气层的)高压脊
参考例句:
  • The path winds along mountain ridges. 峰回路转。
  • Perhaps that was the deepest truth in Ridges's nature. 在里奇斯的思想上,这大概可以算是天经地义第一条了。
4 leftover V97zC     
n.剩货,残留物,剩饭;adj.残余的
参考例句:
  • These narrow roads are a leftover from the days of horse-drawn carriages.这些小道是从马车时代沿用下来的。
  • Wonder if that bakery lets us take leftover home.不知道那家糕饼店会不会让我们把卖剩的带回家。
5 erode NmUyX     
v.侵蚀,腐蚀,使...减少、减弱或消失
参考例句:
  • Once exposed,soil is quickly eroded by wind and rain.一旦暴露在外,土壤很快就会被风雨侵蚀。
  • Competition in the financial marketplace has eroded profits.金融市场的竞争降低了利润。
6 eroded f1d64e7cb6e68a5e1444e173c24e672e     
adj. 被侵蚀的,有蚀痕的 动词erode的过去式和过去分词形式
参考例句:
  • The cliff face has been steadily eroded by the sea. 峭壁表面逐渐被海水侵蚀。
  • The stream eroded a channel in the solid rock. 小溪在硬石中侵蚀成一条水道。
7 sediment IsByK     
n.沉淀,沉渣,沉积(物)
参考例句:
  • The sediment settled and the water was clear.杂质沉淀后,水变清了。
  • Sediment begins to choke the channel's opening.沉积物开始淤塞河道口。
8 densest 196f3886c6c5dffe98d26ccca5d0e045     
密集的( dense的最高级 ); 密度大的; 愚笨的; (信息量大得)难理解的
参考例句:
  • Past Botoi some of the densest jungle forests on Anopopei grew virtually into the water. 过了坊远湾,岛上的莽莽丛林便几乎直长到水中。
  • Earth is the densest of all of these remaining planets. 地球是所剩下行星中最致密的星球。
9 gale Xf3zD     
n.大风,强风,一阵闹声(尤指笑声等)
参考例句:
  • We got our roof blown off in the gale last night.昨夜的大风把我们的房顶给掀掉了。
  • According to the weather forecast,there will be a gale tomorrow.据气象台预报,明天有大风。
10 crater WofzH     
n.火山口,弹坑
参考例句:
  • With a telescope you can see the huge crater of Ve-suvius.用望远镜你能看到巨大的维苏威火山口。
  • They came to the lip of a dead crater.他们来到了一个死火山口。

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