The solar system is divided into an inner solar system and an outer solar system. The inner solar system contains four terrestrial planets, namely Mercury, Venus, Earth and Mars. Counting from the orbit of Jupiter, the outer part is the outer solar system, which is mainly composed of four gaseous planets.
After human beings walked out of the earth, they first explored the planets in the inner solar system. Because of the difficulty of detecting Mercury and Venus, scientists finally focused on Mars. Through nearly half a century of hard work, we have also learned a lot about Mars, and believe that we will be able to board Mars in the near future and establish a human base on Mars.
The inner solar system is far less attractive to scientists than the outer solar system. We know very little about the starry sky beyond the orbit of Saturn, especially at the edge of the solar system, and there are a lot of secrets we don’t know. To explore the outer solar system, the first thing we need to explore is the conditions around the orbits of Jupiter and Saturn.
I believe many friends know that Jupiter and Saturn are the eldest and second largest of the solar system. They are the two gaseous planets with the largest mass and volume among the eight planets. In addition to the mystery of Jupiter and Saturn itself, a large number of satellites around them are also the focus of scientists. The goal of exploration.
The satellites of Jupiter and Saturn add up to 161, which is a huge group of satellites. Among these satellites, some satellites are particularly mysterious and attract the attention of scientists. The earliest human cognition of Jupiter and Saturn came from Pioneer 11, Voyager 1 and Voyager 2, which are interstellar probes, all heading out of the solar system.
These interstellar probes all need to use Saturn and Jupiter to achieve gravitational acceleration, so they all flew by Jupiter and Saturn at close range, so that we can see the appearance of Jupiter and Saturn more clearly for the first time. After Voyager 1 reached the orbit of Saturn, it also changed its orbit to detect Titan, which scientists are most interested in.
The reason why scientists are very interested in Titan is mainly because of observations that it has a very thick atmosphere. You must know that the atmosphere is very important to a planet. A thick atmosphere means that there is an ecosystem on the surface of the planet. The ecosystem is a necessary condition for the birth and evolution of life. Therefore, scientists speculate that there will be life on the surface of Titan?
Although Voyager 1 flew over Titan, the detection equipment it carried was unable to detect the details of the surface through the thick atmosphere. Even so, through some blurry pictures, we also saw Titan’s In addition to being extraordinary, in addition to having a thick atmosphere, it also vaguely saw a liquid lake on the surface.
In order to better understand Titan’s situation, NASA launched the Cassini-Huygens probe in 1997. This probe has two main missions. One is the Cassini probe orbiting Saturn and the other is The Huygens probe landed on Titan. That’s right, this probe is a combined probe, consisting of two probes, one is an orbiting probe orbiting Saturn, and the other is a probe specially prepared for landing on Titan.
After 7 years of voyage, the Cassini-Huygens probe entered an orbit around Saturn on July 1, 2004. On December 15, 2004, the Huygens separated from the Cassini and then headed towards Earth. The Guardian moved forward and was ready to land. On January 14, 2005, it successfully landed on the surface of Titan. Of course, the landing process was dangerously slow.
Because Titan’s atmospheric concentration is twice that of the earth’s atmosphere, Huygens rushed into the Titan’s atmosphere at a speed of 6000 meters per second. When it was 190 kilometers from the surface, the heat shield separated from the main body, reducing the speed. At 0.4 kilometers per second, three parachutes were opened and slowly landed on the surface of Titan. The whole process took up to two and a half hours.
For a probe to land on the surface of the planet, this time is very long. Perhaps many people will ask: Why did the Huygens take so long to land on the surface of Titan? In fact, it is mainly for safety. We must know that we don’t know anything about Titan, and it has a very thick atmosphere. If you want to land safely, it is better to control the speed slower.
Moreover, the Huygens slow landing also has an advantage, that is, a large amount of data about Titan’s atmosphere can be obtained, including composition, pressure and wind, and these data are of great significance to our understanding of Titan. It is also the collection of these data that makes scientists more interested in Titan.
Although Huygens successfully landed on Titan, it only survived for about 90 minutes and then stopped working. Although the time was very short, Huygens still took many photos of the surface of Titan. In these photos, we see a very good ecological environment. There are indeed very large liquid lakes on the surface, more than 100 kilometers in size, but the composition is not water, but methane.
These photos make scientists even more convinced that life is very likely to exist in Titan’s methane ocean. Huygens fulfilled its mission and gave us a new understanding of Titan. At the same time, the Cassini is continuing to detect Saturn and collect data, and has made a major discovery, which has subverted the cognition of scientists.
On November 26, 2005, when the Cassini spacecraft flew over Saturn’s second largest moon Enceladus, it discovered a very strange phenomenon, that is, there is a stream of charged particles near Enceladus, which shows that there is material. The analysis of these data shows that there is a dust disk around Titan, orbiting Titan.
Saturn has huge rings of Saturn, which we all know, but the existence of rings on Rhea is very incredible. It is important to know that according to the existing satellite formation theory, under the powerful gravitational force of giant gas planets like Jupiter and Saturn, the dust material around the satellite should be gradually stripped off, and it is unlikely to form a star ring.
The celestial ring is composed of a large number of fragments, and Enceladus is only 527,000 kilometers away from Saturn. At such a short distance, it is theoretically impossible to have its own satellite system, and there should be no celestial ring. However, the reality has slapped scientists on the theory of satellite formation. Existence is reasonable. Even if the satellite ring of Rhea can exist, it shows that our current satellite formation theory is not perfect and still needs a lot of improvement.