Extraterrestrial ocean

Is life on earth lonely in the universe? With the discovery of more and more extraterrestrial oceans, scientists believe that extraterrestrial life is possible because the ocean is the source of life. The so-called “extraterrestrial ocean” refers to the oceans on other planets other than the earth. Liquid molecules in the ocean can dissolve and transform rocks, thereby providing rich nutrients for the origin and evolution of alien life.

Mysterious bright spot in Ceres crater
In the solar system, in addition to the big planets we know well, there are many smaller planets. There are more than 500,000 of them, mainly located in the asteroid belt between the orbits of Mars and Jupiter. Among the many planets in the asteroid belt, Ceres is the most eye-catching one, because its diameter is about 945 kilometers, and it is the big man in the asteroid belt. Its mass accounts for 1/3 of the total mass of the asteroid belt. Compared with other celestial bodies in the planetary belt, Ceres is so different, so scientists classify it from asteroids and classify it as a dwarf planet.

In March 2015, the “Dawn” probe launched by the United States successfully entered the orbit around Ceres and has been exploring Ceres for more than 3 years. When it was closest to the surface of Ceres, its height was only 35 kilometers. During the exploration, the “Dawn” made a major discovery-Ceres’s Okato crater has some mysterious bright spots. Scientists analyzed the gravity data collected by the “Dawn” to clarify the gravity changes in and around the crater, and combined with computer simulations, they calculated that Ceres has an underground ocean.

Scientists used computers to restore the formation process of Ceres’ bright spots: 20 million years ago, a huge meteorite struck Ceres and smashed out the Okato crater. The attack caused the surface of Ceres to be smashed and numerous cracks were formed. The frozen salt water in the underground ocean spewed out, forming a peculiar “ice volcano” spectacle. Tens of thousands of years later, the salt water stopped spraying, and the water vapor gradually evaporated, leaving behind a large white salt layer. This is the bright spot “seen” on the “Dawn”. If there is life in the underground ocean of Ceres, scientists hope to find fossils of these life in those salt layers.

Europa holds the most water in the solar system
Europa is the fourth largest moon of Jupiter, with a diameter of 3,100 kilometers, which is slightly smaller than the moon. Europa is also very far away from the sun, so there is a layer of ice up to 100 kilometers thick on its surface. The ocean hidden under its ice shell is also amazing. It is 50 kilometers deep on average, and the deepest place on the earth is only about 10 kilometers. Therefore, scientists believe that Europa’s water storage is astonishing, and it is the planet with the most water in the solar system.

Because Europa’s surface is so cold, scientists originally thought Europa would not give birth to life. However, Europa not only has abundant water resources, but also has an atmosphere containing oxygen and water vapor that can support life. What is even more gratifying is that space probes have also discovered clay on the surface of Europa, which is an important material that can support the evolution of life. All these scientific discoveries mean that the possibility of life on Europa is very high.

Scientists once believed that the main salt in Europa’s ocean was sodium sulfate. The Hubble Telescope’s latest observations indicate that sodium chloride may be present on Europa’s frozen crust, and sodium chloride is also the main component of salt in the earth’s oceans. If scientists can confirm that the main salt in Europa’s ocean is sodium chloride, then it is likely that life similar to that on Earth will evolve in Europa’s ocean.

Titan Underground Methane Ocean
Titan is a little smaller than Mars, but it is unusually large in Saturn’s satellite family. Its size is 20 times the size of the other moons of Saturn combined, and is about the same size as Jupiter’s 4 large moons. Unlike them, Titan has an atmosphere and a strange ocean of liquid methane is hidden under its surface.

Alien ocean world in science fiction works

Titan’s surface is extremely cold, and its temperature is close to absolute zero (-273°C), so its outer shell is a layer of methane ice that is thousands of meters thick. The sea of ​​liquid methane is hidden under this ice shell, where the sea surface is as calm as a mirror, without a trace of ripples. Although Titan’s surface is cold, it also rains. The methane rain there is much more violent than any heavy rain on the earth, and after it rains, many methane lakes will be formed. Then, after a 10-year dry period, those liquid methane will gradually volatilize into methane gas. On the earth, methane gas is the main component of the gas we use every day.

The “Dawn” asteroid probe detects Ceres.

Titan has a methane ice crust.

Ice volcano on Triton

If there are creatures on Titan, they must be extremely small and tenacious. On Earth, a water area that is more similar to the methane ocean on Titan is Lake Vostok in Antarctica. Millions of years ago, this lake was frozen under the ice, and since then, its liquid depth has not changed. A Russian scientific research team drilled into the liquid in the lake and found that there were only very simple life forms.

Silicon-based life in Triton’s liquid nitrogen ocean
With a diameter of 2,700 kilometers, Triton is the largest satellite of Neptune. Triton is one of the coldest celestial bodies in the solar system, and its surface temperature is below -233°C. Therefore, the outer shell of Triton is also an ice shell, but it is not water ice, nor methane ice, but rare nitrogen ice. Under the ice shell is the liquid ocean, the main component of which is liquid nitrogen. On the earth, liquid nitrogen is a well-known refrigerant that can help people store and transport food.

Scientists have discovered that there are many radioactive substances inside Triton, which can generate a lot of heat after decay. This is an important reason for the existence of Triton’s underground ocean. Scientists speculate that the radioactive material inside Triton could heat the underground ocean for another 4.5 billion years. Because Triton has ice crusts and underground oceans, it will also have “ice volcanoes”, and the ejection heights of these “ice volcanoes” are amazing, reaching more than 8,000 meters.

Life on earth evolved based on the carbon element, and they are called “carbon-based life”. Because liquid nitrogen is difficult to support carbon-based life, and the radioactivity in Triton’s ocean is particularly strong, the researchers speculate that there may be silicon-based life in Triton’s underground ocean. They evolved on the basis of silicon and have no DNA. Macromolecules such as, protein, etc., and are more like robotic organisms in science fiction works. These silicon-based beings are very small and feed on trace substances (such as silicate, methane, and sulfate) in the liquid nitrogen ocean.

Japanese science fiction writer Yoshiki Tanaka wrote in the “Legend of the Galaxy Heroes”: “My journey is the stars and the sea.” For humans, the stars and the sea are both mysterious and unpredictable. The ocean on the extraterrestrial is a place that scientists desperately want to know in recent years. If mankind can conduct in-depth exploration of the alien ocean and even make use of it, then there will be a solid material guarantee for mankind’s journey into space, and the second home of mankind will no longer be out of reach.