Hua Feng clearly remembers that as of 2004, human understanding of Titan's surface map was still very poor. In any case, humans used the Hubble Astronomical Telescope's infrared and Cassini Huygens to capture a high-brightness, Australian-sized picture.

The unofficial name of this area is ''Xa'

adu Regio'' (Xanadu); Similar Hubble Space Telescopes, Keck Telescopes, and Very Large Telescopes have observed another similarly sized deep field on Titan, where it is speculated that there may be a liquid ocean of methane or ethane, but Cassini's observations have found that it may be something else. Cassini also sent back a large number of high-resolution images of Titan's landscape, including enigmatic linear stripes that some scientists believe may have been the result of tectonic movements in the Earth's crust.

An observation of a flyby of Titan on November 26, 2004, found that Titan's smooth surface had very little impact craters, which contrasted with light and dark. This is probably due to frequent crustal restructuring caused by Titan rain or hydrocarbon snow falling into craters or active volcanic eruptions.

The detector's beamsplitter found that the light and dark areas emit the same wavelength of sunlight, which means they may be made of (or at least covered with the same material). As for what exactly it is, it is still unclear. Hydrocarbon lakes or seas that were once expected to be discovered by probes observing objects or liquids reflecting light have not been detected, leading scientists to suspect that Titan's surface may be completely icy or muddy.

In order to better understand the surface landforms, the Cassini spacecraft used radar remote sensing mapping technology when flying close to Titan. The first image that came back showed that the surface was a complex, rugged and flat area, which appeared to be caused by volcanoes, which could have erupted water and ammonia, and also found some striated landforms that appeared to be produced by wind erosion.

There are also percussion craters that appear to have been filled in, and the liquids in them may be liquid hydrocarbons. What is or is not in the lake is still uncertain. Other areas return signals that may be solid or liquid, but other explanations remain: Titan looks really smooth, with no topography above 50 meters.

Astronomers believe that Titan is home to lakes made of liquid methane and ethane, and that the moon is colder than Antarctica. Scientists say that while Titan is colder, the wind, rain and tectonic processes on it make it the most Earth-like object in the solar system. While the satellite's average surface temperature of minus 292 degrees Fahrenheit and minus 180 degrees Celsius keeps the water solid at all times, it has liquid methane and ethane on its surface, which provide a habitat for life, but are difficult to ignite without oxygen.

In 1655, the Dutch astronomer Christian Huygens pointed his new telescope at Saturn to study Saturn's rings, but to his surprise, there was a huge moon next to Saturn, which was Titan.

In 1907, Spanish astronomer José Comas Sola observed a shadow on the circular border of Titan from a telescope, pointing out that it was a symbol of the presence of an atmosphere.

In 1944, Dutch-American astronomer Gerard Kuiper used a spectrometer to make observations and found the presence of methane gas on Titan.

On September 1, 1979, Pioneer 11 passed by Saturn 20,800 kilometers away from Saturn, taking pictures of Saturn's huge moon Titan. And it was preliminarily judged that the temperature on Titan was extremely low, and life could hardly survive.

On November 12, 1980, Voyager 1 passed by Saturn from 124,000 kilometers away, and nine months later, on August 25, 1981, Voyager 2 passed by 100,800 kilometers from Saturn. The detection results of these two detectors show that the main component of Titan's atmosphere is nitrogen, and the other components are argon (6%), methane (2~3%), and hydrogen (0.6%). The atmospheric pressure on the surface is 1.5×10⁵Pa, but the surface temperature of Titan is very low at -179°C, and at the tropopause at an altitude of 45 kilometers above the surface, the temperature is even lower, at -203°C, which is difficult to expect to give birth to life.

On January 14, 2005, the Huygens sub-probe landed on the surface of Titan, sending back more than 300 images of Titan to a ground observatory.

Voyager 1 and Voyager 2 have explored Titan. Voyager 1 tried to get as close as possible to Titan, but unfortunately there were no instruments on board Voyager 1 that could penetrate the fog on Titan, as it was not known at the time that there were clouds above. Years later, after complex digital manipulation of images taken with the Voyager 1 orange filter, it was still not possible to explain the causes of the bright and dark landscapes such as the Xanadu and Sickle regions, but since then these areas have been observed by the Hubble Astronomical Telescope with infrared.

Voyager 2 has only roughly explored Titan, and the Voyager 2 team had to choose one of the following options: "Adjust the orbit for Voyager 2 to take a closer look at Titan" and "Use another orbit to visit Uranus and Neptune". Since Voyager 1 was not able to observe its surface features, the Voyager 2 team opted for the latter option.

On September 1, 1979, Pioneer 11 flew by Saturn and visited Titan. However, when Pioneer 11 was inspecting Titan, it was caught in a strong solar wind, which seriously affected the information sent back. The ground control center received only five high-resolution photos it took at a distance of 350,000 kilometers. In the photo, Titan is a beautiful orange-red color, like a ripe orange.

Voyager 1 flew to Titan on November 11, 1980. It is only 4,000 kilometers from the top of the clouds, and the exploration has been a complete success. It was this time that Titan's diameter was measured at 4,828 kilometers, instead of 5,550 kilometers as previously thought.

Only three probes, Pioneer 11, Voyager 1 and Voyager 2, have flown to Saturn to explore Saturn. On September 1, 1979, Pioneer 11 became the first probe to visit Saturn after a six-and-a-half-year space journey.

It flew 20,200 kilometers above the cloud summit of Saturn, explored Saturn for 10 days, and sent back the first images of Saturn. Pioneer 11 not only discovered two new rings of Saturn and Saturn's 11th moon, but also confirmed that Saturn's magnetic field is 600 times stronger than that of Earth. On September 2, it crossed the plane of Saturn's rings for the second time and used Saturn's gravitational pull to turn towards Titan, thus probing the planet that could harbor life.

On November 12, 1980, Voyager 1 flew 12,600 kilometers from Saturn, sending back more than 10,000 color photographs. The expedition not only confirmed the existence of Titan, 11, and 12, but also discovered 3 new small moons of Saturn. As it flew less than 5,000 kilometers from Titan, the first exploration analyzed the atmosphere of Saturn's largest moon and found that Titan had neither sufficient water vapor in its atmosphere nor a sufficient amount of liquid water on its surface.

On August 25, 1981, Voyager 2 flew from an altitude of 10,100 kilometers above the cloud summit of Saturn, sending back more than 18,000 images of Saturn. The probe found that Saturn's surface is cold and windy, and the northern hemisphere has strong and stable storms at high latitudes, even more violent than those on Jupiter.

Saturn also has a Great Red Spot, 8,000 kilometers long and 6,000 kilometers wide, probably due to disturbances and rotations caused by updrafts in Saturn's atmosphere as they re-fall into the clouds. From time to time, lightning also passes through Saturn's rings, which are tens of thousands or even hundreds of thousands of times more powerful than lightning on Earth.

It reaffirms that there are 7 rings of Saturn. Saturn's rings are made up of particles and gravel with a diameter of a few centimeters to several meters, with smaller particles in the inner ring and larger particles in the outer ring, which have different colors due to different particle densities. Each ring can be subdivided into thousands of small rings, large and small, and even Cassini seams, which are thought to be empty, have several small rings, and in high-resolution photographs, you can see that the F ring has five small rings intertwined with each other. The overall shape of Saturn's rings resembles a giant densely patterned record, stretching from the top of Saturn's clouds to a distance of 320,000 kilometers.

Voyager 2 discovered 13 new moons of Saturn, bringing the total number of Saturn's moons to 23. It examined 9 of these moons and found that there is a large crater on the surface of Titan, with a diameter of 400 kilometers, the bottom is uplifted upwards and dome-shaped, and there is a huge crack that surrounds the moon for almost 3/4 of a circle; one hemisphere of Titan is dark, the other hemisphere is very bright; Iapetus's rotation period is only 9~10 hours, a far cry from its orbital period of 550 days, Titan's actual diameter of 4,828 kilometers instead of 5,800 kilometers as originally thought, is the second largest moon of the planets in the solar system, it has a dark and cold surface, a sea of liquid nitrogen, a dark red sky, and the occasional sprinkle of nitrogen rain mixed with hydrocarbons, etc., which is ideal for humans to understand the origin of life and various chemical reactions.

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.