They knew that Cassini-Huygens had arrived at Saturn on July 1, 2004, and had begun to use radar to measure Titan's surface topography, and that the Cassini probe had soared above Titan on November 26, 2004, and had taken many high-resolution images of Titan's surface, revealing light and dark patches that had never been seen before with the human eye.

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.

NASA announced on June 27, 2019 that if all goes according to plan, Dragonfly (D

ago

Fly) will launch in 2026 and land on the Titan after eight voyages, after which the probe will cruise the 5,150-kilometer-wide satellite for at least 2.5 years, during which time it will make 24 flights with a total range of about 180 kilometers. The goal of this mission is to document the Titan's chemical composition in detail. Some scientists believe that the hydrocarbon oceans on the Titan may be home to exotic life forms that are unique to them. In addition, because Titan's environment is very similar to that of early Earth, the mission's observations may also help to understand the chemical processes by which life arose on Earth.

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

y

DelGe

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

e

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

ie A

de

so

"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

o Iess) said: "Cassini detected large tidal fluctuations in Titan, which almost certainly led to the conclusion that there is a hidden ocean beneath its surface. "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. ”

What led scientists to make this discovery was the phenomenon of tidal deformation. Saturn's gravitational pull causes Titan to constantly rise or squeeze into shape. If Titan were made entirely of solid rock, gravity from Saturn would cause its surface to uplift and form so-called "solid tides," which should be about 3 feet (about 1 meter) high. However, Cassini's measured data shows that the bulge is as high as 30 feet (about 10 meters). This data suggests that the planet Titan is not entirely composed of solid rocky material.

At first, scientists were not sure that Cassini would be able to detect tidal uplift caused by Saturn's gravity. However, the Cassini probe did just that, flying by Titan six times between February 27, 2006 and February 18, 2011, during which time it made precise measurements of Titan's gravity field. These gravitational field data, with the assistance of NASA's Deep Space Network (DSN), ultimately gave an accurate value of the size of Tidal Uplift on Titan's surface.

Sami A**a

From NASA's Jet Propulsion Laboratory (JPL), who is also a member of the Cassini project team, she said: "We did ultra-high-precision measurements, and we were fortunate to have a very stable connection between the Cassini probe and the Deep Space Network antenna. Tidal uplifts formed by the gravitational forces of Saturn are less significant than those formed on other giant planets, such as some moons of Jupiter. However, in the absence of field drilling conditions, gravity field data is the best way to understand Titan's internal structure. ”

To create a tidal uplift effect of measured size, the ocean layer beneath Titan does not have to be very thick and deep. A layer of liquid water between its hard, deformable shell and the inner rocky mantle layer would allow Titan to orbit around Saturn with the kind of uplift or compression that observations reflect. Since Titan's surface is mostly made up of water ice, which is common in the outer solar system moons, scientists believe that Titan's oceans are also composed mainly of liquid water.

On Earth, gravitational action from the Moon and the Sun causes tides on the surface oceans. In the open sea, this uplift can reach 2 feet (about 60 centimeters). Gravitational pull from the Moon and the Sun can also cause solid tides to form in the Earth's crust with an amplitude of about 20 inches (50 centimeters).

The presence of a liquid ocean beneath Titan's surface does not in itself constitute a conclusion that life may exist here. Scientists tend to believe that life is only possible if there is direct contact between liquid water and rocks. It is not yet possible to confirm whether the bottom of this ocean is made of rocks.

The results of this detection are of great significance for unraveling the mystery of continuous methane resupply on Titan. Methane is abundant in Titan's atmosphere, but researchers believe that methane should be unstable in the atmosphere, and if Titan's atmosphere can remain abundant for a long time, then there must be a source of continuous supply of methane.

Jonathan Lunin

atha

Lu

i

E), a member of the Cassini Project at Cornell University in the United States, said: "The discovery of a liquid water layer beneath Titan is very important because we want to understand how methane is stored inside Titan and how this stored methane is released. "This is very important because all the unusual things about Titan have to do with the abundance of methane, but the methane gas in its atmosphere should have been destroyed in a geological sense for a short period of time," he said. ”

Imagine an underground ocean of liquid water filled with ammonia that rises along fissures and pores to the surface, releasing methane gas from the ice. At the same time, such an underground ocean could also serve as a methane storage pool.