The vast universe is full of water
In many people's minds, Earth may be the only star in the solar system with a huge amount of water. Of its 510 million square kilometers of surface area, the ocean covers 71 percent of it, accounting for 360 million square kilometers, while the land area accounts for only 29 percent.
However, in recent decades, scientists have combined a number of research results to prove that the identity of water has changed from a "scarce thing" to a basic component of the universe, and its traces can be found in many places. In 2011, astronomers discovered a distant star erupting with huge currents of water in the constellation of Perseus. It is estimated that its water flow is equivalent to 100 million times that of the Amazon River, irrigating the surrounding space. There is also an element of water in the huge dust clouds in the universe, freely moving water molecules everywhere in interstellar space, and even those "water planets" (whose surfaces are full of water) around distant stars. They all prove that the existence of water is a universal phenomenon in the universe.
Even in our solar system, the reserves of water are staggering. The amount of water on some of Jupiter and Saturn's moons is unimaginable, including Enceladus
and Ganymede
The amount of underground sea water is likely to exceed the total amount of sea water on Earth. There was also liquid water on Mars, and scientists estimate that its storage is much greater than that of the Arctic Ocean.
Perhaps the largest "reservoir" in the universe is located in the Oort cloud, which astronomers assume is a spherical cloud that surrounds the solar system and is filled with comets.
The scientific community has been divided into opinions about the source of water in the solar system. Two of the more mainstream views are that water was formed by ice ionization when the solar system was formed, and that water originally existed in the cold nebula before the birth of the solar system.
Scientists from the Department of Astronomy at the University of Michigan in the United States provide evidence for the second view: they found that more than 50% of the water on Earth may have been formed long before the birth of the solar system. The results confirm that some of the water in the solar system comes from the interstellar medium before the formation of the solar system. This will most likely help us unravel the mystery of how and when water exists in the solar system and help us find water on other planets in the solar system.
Dr Ilse Cliffs, who led the study, pointed out: "In the environmental conditions of the early days of the solar system, it was not suitable for the synthesis of water molecules, which means that water can only come from external nebulae rich in chemical elements. Even more incredibly, this ice survived the birth of the solar system. ”
In order to determine the "age" of water, the researchers decided to start with the isotope of hydrogen, deuterium, and analyze the ratio between hydrogen and deuterium formed in various environments. Scientists have built specialized computer models to compare the abundance (relative content) of deuterium in comets, planets, meteorites, and Water in Earth's oceans. They found that the samples all had higher rates than the proportion of deuterium in the solar system under normal circumstances.
If water is formed in a cold interstellar medium environment, then the abundance ratio of deuterium to hydrogen will be higher, up to about 1%. If the water had formed in the hotter environment at the time the solar system was formed, the value would have been lower, at only about 0.002 percent. But whether it's a comet, a planet, a meteorite, or an Earth's ocean, the actual observed abundance ratio is between these two extremes, such as 0.016% in Earth's oceans.
The researchers also simulated the interstellar environment at the time of the birth of the sun and studied the formation of deuterium-containing heavy water, and found that the solar system itself was extremely inefficient in forming heavy water. Without that portion of the water from the interstellar medium, we simply cannot explain the deuterium-hydrogen abundance ratio in planets, meteorites, and Earth's oceans. This can only be explained by one point: the extra part of deuterium does not originate from the solar system, but from the cold interstellar space with a higher deuterium abundance.
Cliffs said that some of the water we drink every day is likely to be "older" than the solar system. They speculate that about 7 to 50 percent of the water in Earth's oceans comes from the interstellar medium. For comets, this proportion is likely to be 14% to 100%.
Perhaps, there are many systems similar to the solar system in the universe, and they also have the conditions for the birth of life with the help of the interstellar medium, and it is very likely that human beings will find another "earth" that is pregnant with life.
There is a star made of water in the sky
Ganymede is a moon orbiting Jupiter, with a diameter of about 5,300 kilometers, making it the largest moon in the solar system.
In fact, many scientists have speculated that there is a saltwater ocean hidden under Ganymede's ice sheet. But Steve Vance, an astrobiologist from NASA's Jet Propulsion Laboratory in California, said: "We have confirmed this hypothesis with the help of data from the Galileo spacecraft and the Hubble Space Telescope, which gives us a closer understanding of the structure of the ocean inside Ganymede." ”
Ganymede's oceans lie beneath an ice sheet about 150,000 meters thick and are about 100,000 meters deep, 300 times the average depth of Earth's oceans. It has a huge amount of water, perhaps 25 times the amount of water in the Earth's oceans. And the temperature there is suitable enough to keep it in liquid form.
With ice cubes and liquid oceans, and overlapping stacks of the two, the water on Ganymede forms a multi-layered sandwich-like structure: the top layer of ice covers the surface of the satellite, followed by a layer of liquid water, followed by a second layer of ice, a layer of liquid water below, and finally above the rocks on the seabed, another layer of ice and water.
Like Earth, Ganymede has a fluid iron-rich core whose convective motion makes it the only known moon in the solar system to have a magnetosphere. Under the dual gravitational pull of Ganymede's small magnetic ring and Jupiter's larger magnetic field, two aurora bands appear in Ganymede's high magnetic latitude region. As Jupiter rotates, its magnetic field changes, causing Europa's aurora band to shake, but the "amplitude of motion" is not as large as imagined. Using computer models, the scientists found that it was a saltwater ocean beneath Ganymede's surface that was "resisting" Jupiter's magnetic gravitational pull.
Scientists speculate that the ocean's salts most likely come from some kind of magnesium sulfate. To do this, they also computer modeled the oceans inside Ganymede and simulated in the lab how such saltwater oceans are generated and moved. While the source of these salts has not yet been determined, the researchers say salinity can have a substantial effect on the ocean — if the salts are abundant, then the liquid water on Ganymede can gain enough density and settle to the bottom layer. It also means that liquid water can flow above rocks, providing an environment suitable for microbes to live, a structure that greatly enhances the likelihood of life on the planet. You know, the first life form of the earth was born near the magma vent on the seabed, and this similar interaction between water and rock may have occurred on Ganymede.
Jupiter, as the most likely planet in the solar system to show signs of life, has always been highly concerned by scientists. Among the European Space Agency's Jupiter system exploration missions, the "Jupiter's Ice Moon Explorer" probe is particularly eye-catching. The probe is scheduled to launch in 2022 and is expected to reach Jupiter's orbit in 2030. Its main task is to study the three moons that may have oceans under the surface of Europa, Ganymede and Ganymede, to confirm whether their surfaces contain liquid water bodies that are potentially suitable for human settlements, and the possibility of life.
On May 2, 2012, the European Space Agency announced the inclusion of the Jupiter Systems Exploration Mission in its Cosmic Vision Science Program. Professor Jimenez Canete, Head of The Department of Science and Robotics Exploration, said: "This grand plan is the only way to explore the outer solar system in the future, which includes two important themes: first, what are the conditions for planet formation and the emergence of life; and second, how the solar system works. The program is bound to be a fruitful and exciting scientific project. ”
A Song of Ice and Fire
Mars is another planet that scientists see as highly likely to give birth to life. In the past 20 years, humans have used high-resolution imaging, spectroscopy, mass spectrometry, radar, neutron analysis and other means to explore Mars, and obtained a series of data. The results show that there was indeed water on the surface of early Mars, and there was also an environment suitable for life to reproduce.
American scientists have observed Mars for up to 6 years through ground-based telescopes such as the W.M. Keck Observatory in Hawaii. They speculate that about 4.3 billion years ago, the planet also had a wealth of liquid water resources. Due to the undulating trend of the Martian surface, many rivers flow from south to north and converge into oceans, occupying almost half of the area of the northern hemisphere of Mars. The total volume of this water is estimated to be more than 20 million cubic kilometers, while the Arctic Ocean is only 17 million cubic kilometers. In addition, the local water depth of the Martian ocean may exceed 1.6 kilometers. Suppose liquid water covers the entire surface of Mars, with an average water depth of up to 137 meters.
Although until now, probes launched by humans to Mars have not found direct evidence of life. But scientists have come up with another way to find clues to life — meteorites from Mars. At present, there are more than 120 Martian meteorites recognized and named by the International Meteorite Society!
Last year, a team of Chinese, German, Swiss and Japanese scientists studied a gray-black Martian meteorite that fell into the Moroccan desert in 2011, and the International Meteorite Society named it "Tysent" based on local place names. Although this meteorite that has traveled in the universe for 700,000 years is only the size of a thumb and weighs 6 grams, it is currently the most "fresh" Martian meteorite on the earth, almost tantamount to sampling directly from Mars, which is very precious.
Using laser Raman spectroscopy and chemical analysis, scientists detected more than 10 carbon particles in "Thyscent". They are very small, less than one-tenth of a human hair, and the composition is kerato, similar to coal, which is organic matter. In addition, the researchers also found an increase in light carbon isotopes from Martian meteorites, which is strong evidence that life may have existed on Mars. Lin Yangting, a researcher at the Institute of Geology and Geophysics of the Chinese Academy of Sciences who led the research, explained: "Biological action on earth will make more light carbon isotopes in organic matter, and paleontologists judge whether it is related to life through the changes in carbon isotopes in ancient rocks." ”
This research activity has also attracted widespread attention in the scientific community, and many scientists say that this is the most encouraging scientific argument that human beings have proved that Mars may have had life since they explored Mars.
Perhaps in the eyes of human beings, the label of the earth was "unique". But now, as scientists discover more and more of the source of life in the universe , water , water is no longer a patent of the earth. But isn't the unknown and the mysterious also the charm of the universe and life?