For the first time, scientists have mapped the whole surface of Titan, the largest moon around Saturn. The map confirms existing data showing that Titan has many Earth-like qualities that might be able to support life.
The data was collected by Cassini, a spacecraft operated by the U.S. space agency NASA. The spacecraft studied Saturn and its moons from 2004 to 2017. Astronomers used images and radar measurements from Cassini to create the geological map of Titan.
The map shows Titan as a mixture of flat plains, hills and mountains, windblown sand areas, valleys and lakes. The mapping operation is described in a report publishedin Nature Astronomy.
Rosaly Lopes led the project. She is a planetary scientist at NASA's Jet Propulsion Laboratoryin Pasadena, California. Lopes told the publication that the many similarities between Earth and Titan make the Saturn moona great choice for continued exploration.
Rosaly Lopes领导了该项目。 她是美国加利福尼亚州帕萨迪纳市NASA喷气推进实验室的行星科学家。 洛佩斯告诉出版社，土星与土卫六之间的许多相似之处使土星卫星成为继续探索的绝佳选择。
"Titan has an atmosphere like Earth. It has wind, it has rain, it has mountains," Lopes said. "It's a really very interesting world, and one of the best places in the solar system to look for life."
Titan is the only planet in our solar systembesides Earth to have known bodies of liquid on its surface. But Titan's seas and lakes are filled with liquid methane rather than water. Methane, a gas, behaves as a liquid on Titan because the planet is extremely cold.
土卫六是我们太阳系中除地球之外唯一在其表面上具有已知液体的行星。 但是泰坦的海洋和湖泊充满了液态甲烷，而不是水。 甲烷（一种气体）在土卫六上的作用类似于液体，因为地球非常冷。
At cold temperatures, methane goes through similar changes as rain on Earth. It falls to the surface across the planet to form rivers and lakes and can then evaporate to form clouds again.
The map found that nearly two-thirds of Titan's surface is made up of flat plains, Naturereported. About 17 percent is covered in sandy hills shaped by the wind, mostly around the equator.
Unlike Earth, Titan's sand is made up of carbon, hydrogen, nitrogen and oxygen. Around 14 percent of the surface is considered hilly or mountainous.
Seas and lakes filled with liquid methane cover an estimated 1.5 percent of Titan. The liquid exists mainly closer to the planet's poles, while the equatorial areas remain drier.
Ralph Lorenz is a planetary scientist at the Johns Hopkins University Applied Physics Laboratory in Laurel, Maryland. He told the publication one of Cassini's most interesting discoveries "is that Titan is so diverse." Lorenz added: "It's almost like a completely different world, and this systematic mapping marshals that diversity."
Rosaly Lopes says organic materials– those containing carbon - in Titan's atmosphere are important for the growth of living organisms. "Organics are very important for the possibility of life on Titan, which many of us think likely would have evolved in the liquid water ocean under Titan's icy crust," she said.
拉尔夫·洛伦兹（Ralph Lorenz）是位于马里兰州劳雷尔的约翰·霍普金斯大学应用物理实验室的一名行星科学家。 他告诉出版社，卡西尼号最有趣的发现之一是“泰坦是如此多样”。 洛伦兹补充说：“这几乎就像一个完全不同的世界，这种系统化的映射使这种多样性更加强大。”
Scientists believe the mixing of organic material and liquid could have caused complex molecules to develop, or possibly life itself.
The search for possible life on Titan will continue when NASA launches its Dragonfly mission to explore the planet in 2026. Dragonfly is a drone, or pilotless aircraft. It is designed to capture images from above Titan as well as to land on the planet to collect data.
Dragonfly is not expected to arrive at Titan until 2034. But when it does, Lopes and her team will be excitedly awaiting its findings. "It is not only scientifically important but also really cool - a drone flying around on Titan," she said. "It will be really exciting."
预计蜻蜓要等到2034年才能到达土卫六。但是，一旦做到这一点，洛普斯和她的团队将很兴奋地等待它的发现。 她说：“这不仅在科学上很重要，而且真的很酷：一架无人机在土卫六上飞行。” “这将真的令人兴奋。”
Words in This Story：
plain – n.large area of flat land
diverse – adj.including many different types
marshal – v.bring together
evolve – v.develop over time
crust – n.hard, dry layer on the surface of something
mission – n.a task or job that someone is given to do
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