In addition, Yun Meng told Hua Feng that in order to further explore Saturn and unravel the mystery of Titan's life, the United States and ESA jointly developed the priceless Cassini Saturn probe.

The probe was launched on 15 October 1997 and began a seven-year journey. It is expected to fly into nearby space in 2004 for four years to explore the vicinity of Saturn, and for the first time land on Saturn's largest moon, Titan, for field research. Cassini is about 2.7 meters in diameter and weighs a total of 6 tons, and consists of an orbital probe and a lander.

Its orbital probe, named Cassini, is equipped with 12 instruments, and the lander, named Huygens, is equipped with six scientific instruments. To speed up its flight toward Saturn, Cassini flew by Venus in April 1998 and gained its first acceleration. It then made one revolution around the Sun and flew by Venus again in June 1999, gaining a second acceleration. In August of the same year, it flew near the Earth and gained its third acceleration.

After that, the Cassini probe will pass by Jupiter in December 2000 and get its final acceleration. It is scheduled to reach its destination in July 2004 to join Saturn and enter orbit around Saturn. In November of the same year, the Huygens lander will break away from the Cassini probe and fly to Titan, pass through its clouds, make a soft landing on Titan, and then transmit the detected data back to Earth through the Cassini orbiter flying around Turkey.

Cassini's mission after entering the orbit around Saturn is to fly around Saturn 74 times, investigate Saturn's atmosphere and atmospheric circulation dynamics in situ, and fly to many of Saturn's moons, including 45 times near Titan, and use radar to map the surface structure of Titan through its clouds, and it is expected to send back 500,000 frames of images of Saturn, Saturn's rings and Enceladus at close range. Huygens will be the first probe to land on the moon of a large planet.

During the 2.5-hour landing, it will use its instruments to analyze Titan's atmospheric composition, measure wind speed and detect suspended particles in the atmosphere, and maintain a working state for 1 hour after landing, revealing whether there is a sea of water ice on Titan and whether there is some form of life. The data it collected and the images it took were transmitted back to Earth by the Cassini probe.

Cassini-Huygens arrived at Saturn on July 1, 2004, and began working to survey Titan's surface terrain using radar, and on November 26, 2004, the Cassini probe flew over Titan and captured many high-resolution images of Titan's surface, revealing light and dark patches that the human eye has never seen before. Cassini released Huygens on Christmas Day 25 December 2004, and Huygens entered Titan's atmosphere on 14 January 2005 for detailed exploration. The Huygens probe could send data back before Titan's atmosphere burns up.

In December 2007, the Cassini orbiter saw the Ontario Satellite Lake on its 38th flight near Titan, but it could not be confirmed to be liquid at the time.

With the groundbreaking discovery of the "Ontario Satellite Lake", experts believe that many "pits" similar to the "Ontario Satellite Lake" in other parts of Titan may also be lakes.

In December 2009, NASA confirmed the presence of liquid on the surface of Titan.

The Cassini space probe captures the sun's rays reflected off Titan's surface lakes. This discovery confirms the claim that there is a liquid on the surface of Titan.

Scientists have suggested that there should be many large lake-like basins on Titan's surface, where fluids are present. Titan, Saturn's largest moon, shares many similarities with Earth, and it is this that has aroused great interest among scientists. For nearly 20 years, scientists have built a complete theory about Titan.

They believe that there are liquid hydrocarbons (NGLs) on the surface of Titan oceans or lakes. Titan is also believed to be the only planetary body in the solar system other than Earth in which fluid exists. While Cassini's data does not prove the presence of a huge ocean on its surface, it does clearly reveal the presence of large lakes near Titan's poles.

Since the Cassini probe began orbiting Titan in 2004, scientists have been looking for the phenomenon of "specular reflection". But Titan's northern hemisphere has been in winter darkness, and scientists believe there are far more lakes in the northern hemisphere than in the southern hemisphere.

It wasn't until the autumnal equinox in August 2009 that the sun's rays began to shine directly on the lakes of Titan's northern hemisphere, which was also the beginning of spring in the northern hemisphere.

Due to the interference of the thick atmosphere over Titan, most of the sunlight reflected off Titan's surface is obscured. The Cassini probe also took this rare photo by accident. Photo taken on July 8, 2009.

The Huygens probe, a NASA-European Space Agency collaboration, drifts on a biogas lake on Titan's Titan. A report released by the National Academy of Sciences on July 6 said extraterrestrial life could be much stranger than experts had previously predicted. Scientists need to consider expanding the list of extraterrestrial life signatures to include so-called "weird" life forms that can thrive in places where life on Earth would not survive.

Titan is rich in organic compounds and elements such as nitrogen, similar to the environment in which early life on Earth was formed. Cyanide and hydrocarbons on Titan can be used to form nitriles, which are then hydrolyzed by the planet's water ice to form carboxylic acids and amines, both of which can also produce important amino acids.

However, there are also important factors that restrict the existence of life on Titan. The first is that the temperature is too low, the second is that the presence of liquid water has not yet been discovered, and the third is that Titan is not protected by a magnetic field, so when it sometimes orbits outside Saturn's magnetosphere, it is directly exposed to the solar wind, and the radiation may make life impossible.

Scientists say a huge lake of hydrocarbon "icebergs" on Saturn's moon Titan could form exotic life forms. NASA researchers say the latest theory may also explain the strange readings from the moon's huge lakes and oceans.

This new lake on Titan's surface covers an area of 13,000 square miles (34,000 square kilometers) and is located at Titan's South Pole and has some lake characteristics. Since the Cassini probe arrived in Saturn's system in 2004, scientists have been studying the characteristics of methane lakes near Titan's poles, confirming the presence of methane rain on large, cold moons.

Scientists point out that the new lake is just shallow swampland, but observational data show that when a storm comes, the lake will form liquid methane deep enough to rush forward.

Not long ago, Elizabeth Tuttle, a planetary scientist at Johns Hopkins University's Applied Physics Laboratory in the United States, said: "Thunderstorm models on the surface of Titan show that a single storm can form methane rain tens of centimeters deep. Tony Delgenio, a member of the research team at NASA's Goddard Space Research Associates, is Tony Del Dergno

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IO) said the study was the most direct evidence confirming the presence of liquid methane on Titan's surface.

"This cloud layer over Titan was seen very similar to that of the Earth, and at the same time there were signs of a torrent of liquid on the surface of the area," Tuttle said. Del Geneño added that Cassini scientists had not noticed the formation of the new lake until then, and that when scientists realized that heavy rain was likely to fall in the area, they devoted more effort to observing the characteristics of heavy rain and ignored the signs of new lakes forming on Titan's surface.

Scientists are very excited about the discovery of this study to reveal changes in Titan's climate characteristics, when the Cassini probe arrived in the Saturn system in 2004, when the southern hemisphere of Titan is in summer, the northern hemisphere is in winter, and storm clouds mainly gather in the south pole region of Titan. The season is approaching the equinox, and there are no longer any Southern Hemisphere storms here. "Storms are mainly concentrated in the mid-latitudes, with occasional occurrences at lower latitudes," Del Geneño said. ”

In 2008, the Cassini probe completed a four-year survey mission, and plans to extend the survey time to 2010. The detector is now in good health and the mission operator hopes to extend its working life even further in the future.

Tuttle's colleague in the Johns Hopkins University lab, Ralph Lorez

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z) is not directly involved in this study, noting that studies like this would help people to idealize the characteristics of Earth's climate change. "Titan's atmosphere is rich in methane-damp gas, so there will be strong stormy weather after a long drought," he wrote in an email. ”

On October 31, 2014, NASA's Cassini spacecraft spotted methane clouds in the upper atmosphere of Saturn's largest moon, Titan.

Cary Anderson, scientist of the Cassini project at the Goddard Space Flight Center and first author of the research paper on the discovery

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"It is completely unexpected that methane clouds can form at such a high altitude in Titan's atmosphere," he said. No one thought it was possible before. ”

On July 2, 2012, according to NASA's website, the latest data from the Cassini probe showed that there may be a liquid water layer in the frozen ground of Saturn's largest moon Titan. A paper on the discovery has been published in the latest issue of the journal Science.

Lucia Lees, first author of the paper and member of the Cassini project team, Sapienza University of Rome, Italy

"Cassini detected large tidal fluctuations in Titan, which almost certainly led to the conclusion that there is a hidden ocean beneath its surface," Iess said. "The search for water is an important goal of the solar system, and now we have a new target, possibly water-rich, to target a new object," he said. ”