Chinese Explorer Finds Signs of Recent Water on Mars

A new study suggests water may have existed on Mars much more recently than past evidence has shown.

The research is based on data collected by China's Zhurong explorer vehicle. The explorer, or rover, arrived on the planet in 2021.

Evidence of surface water was found in warmer areas of Mars that might have been fertile enough to support conditions for life, the researchers said. A study reporting the results was recently published in Science Advances.

A scientific team from China's Institute of Geology and Geophysics led the research. The institute is part of the Chinese Academy of Sciences.

Today, Mars has a cold, desert climate. But past studies have provided evidence that ancient Mars had large amounts of water. This is believed to have included rivers, lakes and oceans. A 2015 study by the American space agency NASA suggested that 4.3 billion years ago, Mars likely had an ocean covering nearly half of the planet's northern hemisphere.

There are different theories for what caused large amounts of water to disappear from Mars. The most likely explanation is that the liquid escaped when the planet's atmosphere thinned over time, NASA explains. This let the water evaporate, turning the Martian surface into a frozen desert. The space agency estimates the evaporation² happened about 3 billion years ago.

In the new study, researchers said the Chinese rover observed salt-rich sand dunes⁴ on the surface. The dunes contained breaks, crusts and small hills. The team said these landforms provide evidence that land had frozen and then melted in the areas studied. The melting could have happened as recently as a few hundred thousand years ago, the study said.

The rover's observations were made in an area called Utopia Planitia, a large flat area, called a plain, in Mars's northern hemisphere. The researchers said they believe the dunes were likely formed sometime after 1.4 million to 400,000 years ago, possibly even more recently. Conditions during that period were likely similar to how things are on Mars today.

Xiaoguang Qin is with the Institute of Geology and Geophysics and was a co-writer of the study. He told The Associated Press (AP), "We think it could be a small amount...no more than a film of water on the surface."

The rover did not directly observe water in the form of frost or ice. But Qin said computer modeling and observations by other spacecraft on Mars suggest that even today, at some times of the year, conditions could be right for water to appear.

Planetary scientist Frederic Schmidt is with the University of Paris-Saclay. He was not part of the study. But he said he finds the results notable because they demonstrate how young the dunes are. "This is clearly a new piece of science" for the area, Schmidt told the AP.

The researchers said they believe small openings filled with salty water were created by melting frost or snow. This likely resulted in the small cracks, hard crusty material and other surface changes observed by the rover. The team ruled out wind as a cause, as well as frost made of carbon dioxide, which makes up most of the Martian atmosphere.

The rover has now provided "evidence that there may be a wider distribution of this process on Mars than previously⁵ identified," said Mary Bourke. She is an expert in Mars geology at Trinity College Dublin in Ireland. She added that although the evidence suggests small amounts of water, it could still be important in identifying environments that could support life.

The findings were reported days after China confirmed its Zhurong rover has yet to wake up since going into hibernation⁶ for the Martian winter nearly a year ago. Chinese space officials have said the rover's solar equipment is likely covered with dust, blocking the sun and cutting power to the explorer.

Before it went silent, Zhurong had explored the Martian surface for 358 days and traveled 1,921 meters, space officials said. This was far longer than the rover's planned three-month operation, officials added.

Words in This Story

evaporate – v. when liquid changes from a solid state into a gas or vapor¹

dune³ – n. a hill of sand

crust – n. a hard, dry layer on the surface of something

frost – n. a thin, white layer of ice that forms on surfaces, especially at night when it is cold

distribute – v. to give something out to people or places

hibernate⁷ – v. to go into a sleeping state for a period of time

1 vapor   

n.蒸汽，雾气

参考例句：

• The cold wind condenses vapor into rain.冷风使水蒸气凝结成雨。
• This new machine sometimes transpires a lot of hot vapor.这部机器有时排出大量的热气。

2 evaporation   

n.蒸发，消失

参考例句：

• Be careful not to lose too much liquid by evaporation.小心不要因蒸发失去太多水分。
• Our bodies can sweat,thereby losing heat by evaporation.我们的身体能出汗，由此可以蒸发散热。

3 dune   

n.(由风吹积而成的)沙丘

参考例句：

• The sand massed to form a dune.沙积集起来成了沙丘。
• Cute Jim sat on the dune eating a prune in June.可爱的吉姆在六月天坐在沙丘上吃着话梅。

4 dunes   

沙丘( dune的名词复数 )

参考例句：

• The boy galloped over the dunes barefoot. 那男孩光着脚在沙丘间飞跑。
• Dragging the fully laden boat across the sand dunes was no mean feat. 将满载货物的船拖过沙丘是一件了不起的事。

5 previously   

adv.以前，先前（地）

参考例句：

• The bicycle tyre blew out at a previously damaged point.自行车胎在以前损坏过的地方又爆开了。
• Let me digress for a moment and explain what had happened previously.让我岔开一会儿，解释原先发生了什么。

6 hibernation   

n.冬眠

参考例句：

• Bears wake up in the spring after a winter of hibernation.熊经过一个冬天的冬眠后在春季苏醒。
• The tortoise spends the winter months in hibernation.乌龟在冬眠中度过寒冬季节。

7 hibernate   

v.冬眠，蛰伏

参考例句：

• Bears often hibernate in caves.熊常在山洞里冬眠。
• Some warm-blooded animals do not need to hibernate.一些温血动物不需要冬眠。