If there is life on Titan

  In Marvel movies, the super-villain “Thanks” is an eternal family born on the Titans. This desolate and desolate blue planet has left a deep impression on the audience. In reality, this blue planet has not perished, it has always existed in the solar system.
What does the Titan look like?

  Titan refers specifically to Saturn’s sixth moon-Titan in astronomy. It is the second largest satellite in the solar system after Ganymede, with an average diameter of about 5,149 kilometers, which is 1.5 times that of the moon. It is also the only known satellite in the solar system that has both a dense atmosphere and a liquid ocean. To some extent, it is one of the most similar planets known to our Earth in the entire universe.
  Because Titan’s atmosphere is too thick and dense, and it is almost opaque to visible light, even detectors flying at close distances can hardly see the details of Titan’s surface in visible light and infrared wavelengths. Therefore, since 1655, humans In the three hundred years since Titan was first discovered, we have hardly been able to know what the surface of Titan looks like. Until 2019, planetary scientist Lopus of NASA’s Jet Propulsion Laboratory JPL and his colleagues completed the first global geological map of Titan.

  This geological map shows us the surface profile of Titan. For example, the plain is the most important landform on Titan, accounting for 65% of the surface of Titan; sand dunes and mountain hills account for 17% and 14% respectively; The lakes, seas and ditch nets accounted for only 1.5%; the number of identifiable impact craters is surprisingly small, accounting for only 0.4% of the total area, indicating that Titan’s surface is quite young and active, so most of the impact craters have been erased. . At the same time, these geological units of Titan show a strong latitude distribution. Although these findings are slightly thin, they still give scientists many clues to speculate on Titan’s geological activity and geological history.
  Lifting the veil on the surface of Titan, scientists discovered that Titan is the only known planet with a lake and sea with liquid methane on its surface. It has a methane cycle, and it even rains methane. Judging from the pictures returned by NASA’s Cassini spacecraft, the liquid lake on the surface of Titan reflects sunlight. This is the only scene in the solar system except for the earth. Cassini’s measurements also show that there is a liquid ocean under the Titan Ice Sheet, and it may cover the Titan’s world. Scientists believe that there are conditions suitable for life to survive here. These findings undoubtedly make Titan the “hot” planet most likely to breed life.
  If life existed on Titan, what would they be like?
Titan cell membrane envisioned by scientists

  Chemical engineers and astronomers from Cornell University in the United States have jointly developed a set of simulated Titan biological templates. Based on the large amount of liquid methane on the Titan surface, they believe that Titan may have methane-based cells that do not require oxygen and can metabolize. , Copy and multiply, do anything that life on earth can do.
  And we all know that cell membranes are essential for biological cells. They are like conscientious guards, keeping away unwanted substances and allowing nutrients to enter; while helping the cell to expel waste, it also protects the internal integrity of the cell. It can be said that having such a membrane structure is a major prerequisite for biological evolution, which gives organisms the opportunity to produce more complex internal structures and evolve into advanced life forms.
  On the earth, water is considered a necessary prerequisite for the survival of cell membranes. But if the existence of cell membranes is not based on water, but on methane, is it feasible?
  Scientists call the cell membranes they theoretically build nitroplasts. Since no free oxygen is found on Titan, they believe that these nitroplasts are composed of nitrogen, carbon, and hydrogen molecules known to exist in Titan’s low-temperature ocean, but they The stability and flexibility should be similar to liposomes on earth. So what kind of substance is nitroplast composed of? Based on this, the scientists used a molecular dynamics method to screen candidate compounds to see if there are suitable substances that can be used to self-assemble into a membrane-like structure.
  Soon they discovered that acrylonitrile exhibited excellent stability and flexibility, and it had the most potential as a nitrogen substance. Acrylonitrile is a colorless, toxic liquid organic compound that is used on earth to make acrylic optical fibers, resins and thermoplastics. The most important thing is that this compound exists in Titan’s atmosphere, and the content is very abundant.
  In addition, the scientists explored the structural mode of this nitroplast. Acrylonitrile can form a stable membrane structure, thereby separating the internal and external environments of the membrane and realizing the interaction of substances. This means that there is very likely a structure similar to biological cells on Titan!
  But unfortunately, when scientists used computer modeling to simulate the assembly process of using acrylonitrile as a membrane, they found that the membrane could not complete self-assembly at all under the same environment of Titan. In other words, there is still no possibility of self-grown biological cells on Titan.
  Many people are very disappointed when the research is carried out here. They have clearly discovered a planet so similar to ours, but they have never been able to prove that it has the same ability to breed life as ours.
Let nuclear-powered drones go to Titan

  Some scientists pointed out that given the extremely low temperature on Titan, biological macromolecules will be immobile on it. If life exists on the Titans, they will need to rely on the slow diffusion of smaller molecules to complete their movement. However, any membrane will prevent this degree of spread, so they believe that the potential life on Titan may not need membrane at all.
  Of course, this theory was quickly refuted by other scientists. Most scientists still insist that the existence of membrane is essential to maintain the balance between the inside and outside of the cell. Without it, it is impossible to prevent the loss of organic molecules that are beneficial to life to the environment. Nor can it protect the inner substance or exchange it with the outer substance. After all, whether in Titan or anywhere else, life needs to maintain the integrity of the smallest unit of life, the cell, and only this structure can support the evolution of organisms into more complex life forms.
  Although many people regret the current exploration of Titan’s life, scientists have not given up. They believe that there may be any form of life on Titan, and may even live in a very extreme environment, beyond our imagination.
  NASA announced a new mission called “Dragonfly”, a nuclear-powered drone that is scheduled to be launched in 2026 and is expected to reach Titan in 2034. In the two-year planned mission, the “Dragonfly” will travel the distance equivalent to the entire California of the United States, and move to another place every 16 Earth days (or a Titan day), and collect data at the same time. Members of the Dragonfly team said that this may be one of the boldest and most transformative space missions in our lives. We will go to this beautiful planet to find life.
  Will there really be life on the Titans? What is the structure of life there? Let us wait and see, wait for “Dragonfly” to take us to explore!