This paper takes part in the series essay competition of “great science” of Recordunkown.
The earth is a livable planet. It is the home where human beings have lived for millions of years. After human beings walk out of the earth, we begin to search for extraterrestrial life. Scientists mainly search for extraterrestrial life based on the earth’s ecology.
The birth of life on the earth indicates that the earth has all kinds of material and natural conditions needed for the survival of life. If other planets also have similar ecological environment on the earth, then the possibility of the existence of life will be very high. Unfortunately, the solar system has only the earth, a beautiful ecological planet, and there is no second livable planet very similar to the earth.
If so, does it mean that life exists only on the earth in the solar system, and it is impossible for other planets to exist? In the early days, scientists also thought so. However, with the continuous progress of human science and technology and the continuous improvement of human cognition of life, the conditions for extraterrestrial life are also being relaxed.
Nowadays, the search for extraterrestrial life is no longer limited to the ecological environment of the earth, because in the universe, the same ecological planet as the earth may be very rare or even non-existent. From the perspective of cosmic scale, life may be universal in the universe. If so, it shows that the requirements of life for the ecological environment are diverse.
No matter what the basic requirements of life for the ecological environment are, different planets may have different forms of life. However, if a planet wants to have life, some of the most basic conditions must be met. One of the most important basic conditions has been generally recognized by scientists, that is, there must be an atmosphere.
The earth can form an excellent ecosystem and give birth to life, which has an important relationship with the earth’s thick atmosphere. The atmosphere is very important for the protection of a planet’s surface. As we all know, the universe is not peaceful. There are many disasters that can threaten the planet’s surface, such as the impact of some asteroids.
If a planet does not have an atmosphere, such as the moon, then the asteroid will directly hit the surface of the planet, causing devastating disaster. And with the atmosphere, it can produce resistance, generate heat through friction, and consume asteroids before they hit the ground, so as to protect the ecosystem on the planet’s surface.
More importantly, the universe has too much, too strong radiation, which is the end of life. Life can adapt to all kinds of complex and harsh planet surface environment, but it has little resistance to the strong radiation in the universe. Besides the magnetic field, the atmosphere is more important to absorb and block the cosmic radiation.
It can be seen that the atmosphere is very important for the birth of life. When scientists are looking for extraterrestrial life, their main goal is to put on the planets with obvious atmosphere. Mars attracts more attention from human beings, one reason is that it is close to the earth, the other reason is that it has a thin atmosphere, with which life may exist.
So besides Mars, do scientists find planets in the solar system that are more likely to give birth to life than Mars? The answer is yes. Scientists have found a planet very similar to the early Earth, which has an atmosphere and liquid matter, and is more likely to have life than Mars.
This planet is not a planet, but Titan, Saturn’s largest moon. Titan, also known as Titan left, is Saturn’s largest satellite and the second largest satellite in the solar system. As a satellite, its mass and volume can’t be compared with that of a planet. Because of its small mass, a satellite basically doesn’t have an atmosphere.
However, through observation, scientists found that Titan is a different satellite. It has a thick atmosphere, 98.44% of which is nitrogen. It is the only nitrogen rich star in the solar system except the earth. This atmospheric structure is very similar to that of the early Earth, and is called a replica of the early Earth by scientists.
In order to explore Titan, NASA launched Cassini in 1997. Besides exploring Saturn, its more important mission is to explore Titan. Through Cassini’s 20 years of hard work, it has sent us a lot of data about Saturn and Titan.
Through these data, we have a preliminary understanding of Titan. Titan is very similar to the early Earth. There are not only thunderstorms, mountains, basins and so on, but also liquid matter on the surface. So is this liquid going to be water? Of course not. In fact, there is no oxygen in Titan’s atmosphere. Besides the main nitrogen, there are more methane and ethane.
Titan’s Thunderstorm did not drop water, but liquid methane and ethane, which fell to the surface in the form of rain, forming a methane ocean. Methane is also a kind of organic matter, and on earth, the main source of methane is microorganisms.
Titan has a deep atmosphere and a special ecosystem of its own, so it is very possible for this planet to have a special life based on methane. Oxygen is not necessarily necessary for life to breathe and survive. It can be carbon dioxide or methane. Therefore, Titan is highly suspected of the existence of life. In the future, scientists will have two main goals to discover extraterrestrial life, one is Mars, the other is Titan.
Of course, it’s more difficult to explore Titan than Mars, because Titan’s atmosphere is thicker and its surface temperature is as low as minus 179 degrees Celsius. These environments undoubtedly add a lot of difficulties to the landing of the probe, and the Cassini launched by human beings is also observing Titan in orbit, and has not really landed on the surface of Titan.
Because Titan has a thick atmosphere and is blocked by clouds, we don’t know more about its surface. If you want to understand the surface of Titan and know whether there is life, then you need the detector to actually land on the surface of Titan, and it may take some time to achieve this goal.
Scientists have planned to explore Titan again. The next exploration may try to land the probe on the surface of Titan. If there is any special life on it, something will be found. Moreover, scientists’ expectations for the existence of life on Titan are much higher than those on Mars. It is possible that in the near future, human beings will discover for the first time that extraterrestrial life will be realized on Titan.