Europe, the frozen moon near Jupiter, is consideredone of the most habitable worlds in the solar system. It was first examined in detail by the Voyager-1 probe in 1979, showing the surface almost devoid of large craters. This suggests that water regularly flows upward, renewing the surface of the satellite. Europe is also dotted with long depressions, folds and ridges, potentially made of icebergs floating in meltwater or slush. But in the late 1990s, Europe became truly interesting.
The Galileo Mission found evidence thatbeneath the surface of Europe is a liquid ocean of salt water. The fact that it is salty allows us to understand that water can come into contact with rock — a process that can provide energy in water to nourish microbial life.
But there were too few observations and they werelimited, so we can not specifically say how deep and salty this ocean is - let alone what salts are there. And now, a new study published in Science Advances shows that it may well be the usual table salt (sodium chloride) - like on Earth. The consequences of this discovery will be important for the possible existence of life in the hidden depths of Europe.
Scientists believe that the hydrothermal circulation inoceans associated with hydrothermal vents can naturally enrich the ocean with sodium chloride as a result of chemical reactions between the ocean and the stone. On Earth, hydrothermal vents are considered a source of life, for example, bacteria. It was found that the plumes ejected from the south pole of Saturn’s Enceladus satellite, which has a similar ocean, contain sodium chloride, which makes Europe and Enceladus even more attractive objects for research.
Is there life on Enceladus?
If you look at the spectrum of lightdepending on the wavelength), reflected from the surface, we will be able to understand what substances are there. In this case, scientists have found water ice. But there are two others: “hydrated” sulfuric acid and sulphate salt. Where are they from? Scientists studying the subsoil of Europe, or those who are exploring the astrobiological potential of the ocean of this moon, ask an interesting question: did these materials come from inside Europe?
Like our Moon and Earth, Europe is tidalassociated with Jupiter, that is, always looking at him with the same side. Observations of "Galileo" revealed the presence of "hydrated" sulfuric acid on the side of Europe, which is the "rear hemisphere." To make sulfuric acid from water ice, you need a source of sulfur and energy for a chemical reaction. Some of this may appear from the inside of the moon in the form of sulphate salts, some may be delivered by meteorites, but the most likely explanation is that it was all born by Io's volcanic satellite.
Sulfur could be thrown into space by the volcanoes Io andeventually came to Europe. Moving faster than Europe, this sulfur, most likely, hit the back of Europe and plunged into the ice. The energy required for all of this came from electrons in the radiation belts of Jupiter. For the most part, they fly around Jupiter faster than Europe, fall on its back side and deliver a lot of energy.
The measurements also showed the presence of sulphate salts like magnesium sulphate (Epsom salt), but it is unclear where they come from.
Scientists have concluded that the side of Europe,facing its orbit, protected from sulfur bombardment, may be the best place to look for evidence of what salts actually exist within Europe.
There are distinctive features in the visible part of the spectrum.- "color centers" - which appear when irradiated with very energetic electrons. With the help of the Hubble Space Telescope, we managed to find these color centers in the spectrum of Europe, as well as a surface feature located exclusively in a “safe” place on the side of the moon, looking at the orbit, and there was sodium chloride. Everything shows that he could actually come out of the depths of Europe.
Life as we know it needs liquid waterand energy. The fact that Europe has a liquid ocean, tells us that there is liquid water and a source of energy that does not allow it to freeze. But the chemical composition of the ocean is also important. Salt water freezes at a lower temperature than pure water, which means that such water becomes more habitable.
Salt, especially sodium ions in table salt,also play an important role in a number of metabolic processes in plant and animal life. On the contrary, some other salts, such as sulfates, can interfere with life. Perhaps, salt will be just part of the natural layers of ice. But for those who hope to find life in Europe, the discovery of sodium chloride is great news.
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