In addition to eating, sleeping, training, and cultivating every day, Hua Feng formed a three-person team with Yun Meng and Bai Feng, and hurried to the mimic classroom in the dungeon where there were occasional crowds.

He noted that the Titan-Saturn program is a joint initiative between NASA and the European Space Agency (ESA) to explore the moons of the Saturn system, including Titanus, and that it competes with Europa.

In February 2009, NASA and the European Space Agency announced that they would prioritize the implementation of Europa's-Jupiter program, and that they would continue to study the feasibility of the Titan-Saturn program.

The Cassini spacecraft, launched in the late twentieth century and arriving near Saturn in the early twenty-first century, provided a wealth of data that solved many of the mysteries left behind by the traveler's visit.

In 2005, Cassini flew Enceladus several times up close, gaining a wealth of data on the moon's surface and its environment, in particular the discovery of water-rich plumes ejected from the moon's Antarctic region.

This discovery, along with the presence of detectable escape internal energy and the rare presence of impact craters in Antarctica, together with the evidence that Enceladus is still geologically active, in the giant planet's satellite system, many of which fall victim to orbital resonance, which causes stellar vibrations and orbital disturbances, and for satellites closer to the planet, tidal effects heat the planet's interior, which may explain Enceladus' geological activity.

In 2017, Cassini sent back data showing that a plume of water vapor ejected from Enceladus' surface under the ice contained large numbers of hydrogen molecules, which researchers speculated were caused by hydrothermal reactions between Enceladus' oceans and rock cores. If speculation is correct, Enceladus' oceans may also contain methane, an important chemical that supports life.

Enceladus (Encladorus) is named after the giant Encladorus from Greek mythology. This name, along with the names of the first six moons of Saturn, was named by William Herschel's son, John Herschel, in his 1847 book Results of Ast

o

omical Obse

vatio

s made at the Cape of Good Hope). The reason for the name is that Saturn, the god of agriculture, Saturnus, is the leader of the Titans in Greek mythology, Kronos.

The International Astronomical Union named Enceladus's surface after the names of people and places in the Arabic literary work One Thousand and One Nights. Impact craters are named after people, while other geological formations such as deep valleys, ridges, plains, and trenches are named after locations.

To date, the International Astronomical Union has officially named 57 geological formations, 22 of which were discovered for Voyager in 1982, and 35 geological formations discovered by Cassini in three flyings in 2005 were recognized in November 2006. These recognized names include the Samarkand Trench, the Aladdin Crater and the Ceylon Plain.

Enceladus is a relatively small moon, with an average diameter of 505 kilometers, only one-seventh the diameter of the Moon, slightly smaller than the maximum length of the British Isles, and about the same size as the British Isles. And Arizona and Colorado could accommodate the satellites.

However, its sphere is much larger than these areas, with an area of 800,000 square kilometres, equivalent to the land area of Mozambique and 15% larger than the state of Texas. Enceladus ranks sixth in mass and diameter among Saturn's moons, behind Titan (5,150 km), Titan (1,530 km), Titan (1,440 km), Titan (1,120 km) and Titan (1,050 km).

It is also one of the smallest globular moons of Saturn, with the exception of Enceladus (390 km), all of which are irregularly shaped.

In fact, Enceladus is a flat ellipsoid, and according to the photographs sent back by Cassini, the triaxial length of Enceladus is estimated to be 513(a)×503(b)×497(c) kilometers, where (a) is the distance between the poles facing Saturn and the opposite of Saturn, (b) is the distance between the concave and convex poles of the star, and (c) is the distance between the south pole and the north pole. Enceladus rotates around its minor axis, while its major axis deviates radially away from Saturn.

In August 1981, Voyager 2 made its first close-up observation of Enceladus. After analyzing the obtained image information, the scientists found at least five different types of terrain, including impact crater terrain, flat terrain (younger), and near flat terrain, there are often ridges, as well as a large number of linear ground fissures and cliffs. Given the small number of impact craters distributed in flat areas, scientists speculate that these flat areas may have been formed only a few hundred million years ago.

Therefore, in a relatively recent geological time, geological activities such as "water volcanoes" must have occurred on Enceladus to smooth the original porous surface. Solid water (ice) changes the surface of Enceladus so much that it makes it the most reflective object in the solar system, with a geometric albedo of up to 138%. Because it reflects so much sunlight, its flat surface has a night temperature of only -198°C (colder than other Saturn moons).

Cassini flew by Enceladus three times on February 17, March 9, and July 14, 2005, and observed more details on the surface of Enceladus. For example, the flat terrain observed by Voyager 2 is actually an area with a small distribution of impact craters, such areas also contain ridges and cliffs, and a large number of cracks have been found in areas of older geological age and dense craters, which proves that the area also experienced violent geological movements after the formation of a large number of impact craters, and in areas that Voyager 2 did not survey in detail in the past, several younger terrain were found, such as an odd terrain near Antarctica.

Jets of water ice ejected from Enceladus appear to pass over the bright side of Saturn. The photo was taken by NASA's Cassini spacecraft. In fact, Enceladus orbits about 112,000 miles (180,000 kilometers) from the tip of Saturn's atmosphere. Discovered in 2005, Enceladus' icy geysers are located in the fault zone of the planet's southern hemisphere, where their jets are thought to originate from the liquid water layer beneath the surface.

Impact craters are a common phenomenon found on many celestial bodies in the solar system. Many areas of Enceladus are covered by clusters of impact craters with varying densities and varying degrees of damage. On the basis of the observations of Voyager 2, scientists divided the crater into three types of topographic units according to the different density of the craters.

CT1 and CT2 contain a large number of craters with a diameter of 10-20 km, while CP is a flat area with a small number of craters. This subdivision of crater terrain based on crater density (and associated surface age) supports the view that Enceladus has undergone multiple stages of surface remodeling.

Recent Cassini observations provide more detailed information about the CT2 and CP topographic units. These high-resolution photographs show that many of Enceladus' impact craters are severely damaged by sticky collapses and structural fractures. Viscous collapse is the destruction of the terrain caused by impact craters and other water ice caused by gravity, and this process takes a long geological time and will eventually flatten the terrain of the area.

The effect of this depends on the temperature of the ice, as ice that is hotter and harder is more likely to be destroyed. Impact craters that have undergone viscous collapse generally have a convex bottom, and sometimes only a rim remains. The convex bottom of the large impact crater in the upper left corner of Figure 8, the Dunyazad crater, is an example of viscous collapse. In addition, many of the impact craters on the surface of Enceladus have been severely damaged by structural fractures.

The impact crater with a diameter of almost 10 kilometers to the right-hand side at the bottom of the photograph is proof of this: the edge and bottom of the crater have been severely damaged by an elongated rift that is only a few hundred to a kilometer wide. To date, almost all of the impact craters located in the CT2 topographic unit show signs of tectonic deformation, as evidenced by the role of viscous collapse and structural fractures—although the crater terrain area is the oldest and most preserved area of the crater on Enceladus, almost all of the craters are in some form of destruction.

Voyager 2 discovered several geological formations on Enceladus, including trenches, cliffs, and ridges. Recent Cassini observations suggest that tectonics are the main way in which the landscape is altered on Enceladus. One of the more interesting geological formations found on Enceladus is the fissures, which can extend up to 200 kilometers long, 5-10 kilometers wide and 1 kilometer deep. Figure 7 shows a typical large rift cutting through areas that are geologically old and have been structurally damaged. This geological formation is also shown at the bottom of Figure 8. A rift is a younger geological formation because it usually appears as a cut through other geological formations with protruding outcrops on both sides of the fracture.

Another example of tectonic action on Enceladus is the trench structure, which consists of a series of curvilinear grooves and ridges. This striped structure was first discovered by Voyager 2 and is often a marker for the division between flat terrain and impact crater terrain. This geological formation can be seen in both Figure 6 and Figure 10 (Samarkand Trench in Figure 10). This grooved topography is reminiscent of similar topography on Europa.

However, the groove structure of Enceladus is more complex than the latter: the grooves on Ganymede are arranged in parallel, while the grooves on Enceladus are more messy and more jagged. Of particular interest is the fact that Cassini made observations of the Samarkand trench and found a number of dark spots (125-750 m in diameter) that were arranged parallel to the trench, and it is speculated that these dark spots were craters located in the area.

In addition to this, there are a variety of geological formations on the surface of Enceladus. Figure IX shows a narrow fracture terrain (often hundreds of meters wide) that was discovered by Cassini. These fissures often penetrate the crater terrain and are only one or two hundred meters deep. Many of these fractures are affected by the thin topsoil generated by the impact crater during their formation, resulting in frequent changes in crack orientation.

Voyager 2 found two types of flat terrain on the surface of Enceladus. The low relief of these terrains and the small number of impact craters compared to the crater terrain indicate the relatively late generation of this geological formation. A typical example of this, the Ceylon Plain, shows no visible impact craters from the photographs.

In the southwestern part of the Ceylon Plain, another flat terrain is crisscrossed with several grooves and cliffs. Later, Cassini also observed and photographed these flat terrains, including the plains of Ceylon and Tia. These photographs show that the terrain is actually full of lower ridges and shallow crevasses.

It is believed that the cracks are due to shear deformation. Photographs of the Ceylon Plain show that there are still a number of tiny impact craters in the area, which are estimated to be between 170 million and 3.7 billion years old, depending on the distribution of the craters.

The expansion of Cassini's observation area on the surface of Enceladus has allowed more flat terrain to be discovered, especially on the spherical surface of Enceladus in the direction of its orbital motion. These terrains are covered with a large number of trenches and ridges, similar to the deformation tectonics of the Antarctic region. These topography are located exactly on the opposite of the spheres of the Ceylon and Tia Plains, suggesting that this region was influenced by Saturn's gravitational tides.