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VOA科学技术2024--Study: Saturn's Moon Titan Has Huge Layer of Methane-filled Ice

时间：2025-01-22 07:19:37

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New research suggests Saturn1's moon Titan has a thick ice cover that could be warming lower areas and supporting molecular2 growth.

Scientists at the University of Hawaii carried out the new study. It appears in The Planetary Science Journal. The findings add to existing evidence that Titan may hold the right mix of materials to support possible life.

No life forms have been confirmed on Titan, a cold, icy world. But past studies suggest the moon now has a large layer of ice that once supported widely flowing water on the surface. Titan is also thought to contain a dense3 atmosphere rich in nitrogen and methane4, both of which are found in Earth's own atmosphere.

NASA reports Saturn has a total of 146 moons orbiting it, more than any other planet. Titan, an ice giant, is the largest of them.

For more than 10 years, NASA's Cassini spacecraft studied Saturn "and its complex system of rings and moons," the space agency said. The new study used NASA data to closely examine surface details of Titan.

The researchers used computer modeling to examine different elements of Titan's surface. One of the main discoveries was that many craters6 examined on Titan's surface were not as deep as some other moons. The team reported that in some cases, craters were hundreds of meters shallower, or less deep, than scientists expected. In addition, only 90 craters were identified on the whole moon.

"This was very surprising because, based on other moons, we expect to see many more impact craters on the surface," said University of Hawaii's Lauren Schurmeier, who led the study.

She said the research team had also expected to see much deeper craters. "We realized something unique to Titan must be making them become shallower and disappear relatively7 quickly," she said.

Computer modeling carried out by the researchers showed how the surface might have changed to remove signs of major impact craters. The researchers said one of the most likely causes of such change was that the moon's icy surface is covered with a thick layer of solid water ice, with methane gas trapped inside.

The team said the data examinations suggest Titan has a methane-filled icy crust that is from five to 10 kilometers thick. The modeling operations run by the scientists produced images that looked similar to crater5 formations on Titan's surface.

Schurmeier said the methane crust, "warms Titan's interior" and can cause surprisingly fast changes to the surface structure. Schurmeier noted8, for example, that crater shallowing on Titan is believed to be happening at a rate "that is close to that of fast-moving warm glaciers10 on Earth."

The surface of Titan is estimated to be about minus 179 degrees Celsius11. Because of this extreme cold, liquids on the moon's surface take the form of ice, with methane gas locked inside, the researchers said. This gas could help warm surface levels beneath, possibly permitting molecules12 to rise toward the surface.

Schurmeier said studying the thickness of Titan's icy crust is important because it might help explain how the moon's atmosphere began to develop. The measurements could also provide additional information on Titan's changing climate.

"Titan is a natural laboratory to study how the greenhouse gas methane warms and cycles through the atmosphere," she said. The resulting information, she added, can provide important insights about such processes happening on Earth.

NASA's Cassini spacecraft ended it mission in 2017, when it crashed into Saturn's atmosphere. But the U.S. space agency has plans to send another explorer to Titan in 2028. That mission calls for a spacecraft called Dragonfly to travel to Titan to observe many different areas. The planned explorer, called a rotorcraft, operates similar to a helicopter.

I'm Bryan Lynn.

Bryan Lynn wrote this story for VOA Learning English, based on reports from the University of Hawaii at Manoa, the University of Lisbon and NASA.

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Words in This Story

layer - n. an amount of something covering a surface

crater - n. a hole left in the ground by an object that hits it with a huge force

impact - n. the force or action of one object hitting another

unique - adj. different from everyone and everything else

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

glacier9 - n. a large mass of ice that moves very slowly, usually down a hill or valley


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1 Saturn tsZy1     
n.农神，土星
参考例句：
  • Astronomers used to ask why only Saturn has rings.天文学家们过去一直感到奇怪，为什么只有土星有光环。
  • These comparisons suggested that Saturn is made of lighter materials.这些比较告诉我们，土星由较轻的物质构成。
2 molecular mE9xh     
adj.分子的；克分子的
参考例句：
  • The research will provide direct insight into molecular mechanisms.这项研究将使人能够直接地了解分子的机理。
  • For the pressure to become zero, molecular bombardment must cease.当压强趋近于零时，分子的碰撞就停止了。
3 dense aONzX     
a.密集的，稠密的，浓密的；密度大的
参考例句：
  • The general ambushed his troops in the dense woods. 将军把部队埋伏在浓密的树林里。
  • The path was completely covered by the dense foliage. 小路被树叶厚厚地盖了一层。
4 methane t1Eyx     
n.甲烷，沼气
参考例句：
  • The blast was caused by pockets of methane gas that ignited.爆炸是由数袋甲烷气体着火引起的。
  • Methane may have extraterrestrial significance.甲烷具有星际意义。
5 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。
6 craters 1f8461e3895b38f51c992255a1c86823     
n.火山口( crater的名词复数 )；弹坑等
参考例句：
  • Small meteorites have left impact craters all over the planet's surface. 这个行星的表面布满了小块陨石留下的撞击坑。 来自《简明英汉词典》
  • The battlefield was full of craters made by exploding shells. 战场上布满弹坑。 来自《现代英汉综合大词典》
7 relatively bkqzS3     
adv.比较...地，相对地
参考例句：
  • The rabbit is a relatively recent introduction in Australia.兔子是相对较新引入澳大利亚的物种。
  • The operation was relatively painless.手术相对来说不痛。
8 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。
9 glacier YeQzw     
n.冰川，冰河
参考例句：
  • The glacier calved a large iceberg.冰河崩解而形成一个大冰山。
  • The upper surface of glacier is riven by crevasses.冰川的上表面已裂成冰隙。
10 glaciers e815ddf266946d55974cdc5579cbd89b     
冰河，冰川( glacier的名词复数 )
参考例句：
  • Glaciers gouged out valleys from the hills. 冰川把丘陵地带冲出一条条山谷。
  • It has ice and snow glaciers, rainforests and beautiful mountains. 既有冰川，又有雨林和秀丽的山峰。 来自英语晨读30分（高一）
11 Celsius AXRzl     
adj.摄氏温度计的，摄氏的
参考例句：
  • The temperature tonight will fall to seven degrees Celsius.今晚气温将下降到七摄氏度。
  • The maximum temperature in July may be 36 degrees Celsius.七月份最高温度可能达到36摄氏度。
12 molecules 187c25e49d45ad10b2f266c1fa7a8d49     
分子( molecule的名词复数 )
参考例句：
  • The structure of molecules can be seen under an electron microscope. 分子的结构可在电子显微镜下观察到。
  • Inside the reactor the large molecules are cracked into smaller molecules. 在反应堆里，大分子裂变为小分子。

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