What is Enceladus hiding in the dark waters of his ocean?

Enceladus Is one of the 82 known satellites of Saturn. About 10 years ago, NASA scientists named Enceladus most livable place throughout the solar system. It turned out that deep under the surface of this satellite, under its ice crust, ocean currents similar to those on Earth can be hidden.

According to a new analysis of the layer of ice that covers the global water ocean of Saturn’s moon, it can be concluded that there is currents very similar to earthly… If this is true, then the ocean of Enceladus is not homogeneous.


Geysers at Enceladus. The picture was taken by the Cassini probe. (NASA / JPL / Space Science Institute)

Enceladus is not easy to reveal his secrets!

For the first time it was possible to get a better look at it only in 1981, when Voyager 2 flew past him, heading for the more distant planets of the solar system. On the imagesmade by the probe, people saw a small ball of ice. It has an almost white, highly reflective surface. The average diameter of Enceladus is only 500 kilometers. The satellite is covered with craters and indented with long cracks and ridges, which indicates its geological activity.

Then, in 2010 year, we were in for a surprise: a probe of Saturn called “Cassini” discovered geysers on the satellite. They spewed water vapor from cracks in Enceladus’s ice shell. This gave reason to believe that the satellite was not completely covered with ice, but hid a liquid salty ocean under the surface.

The combination of liquid water and cracks in ice helped scientists understand how Enceladus works. Enceladus revolves around Saturn in 32.9 hours, having a slightly elongated, oval shape orbit… Thus, he is moving away from the planet, then approaching it, and, accordingly, the gravitational influence of Saturn from time to time intensifies and weakens. This tension is what causes heating the bowels of the satellite, providing its geothermal activity, and also creates cracks on the ice surface or expands them (during the maximum distance of Enceladus from Saturn).

Thanks to the internal heat, the ocean remains liquid, and it can gush through the cracks, after which the water reaches the surface and freezes again… Internal heat will also generate vertical convection flows, similar to terrestrial… Warmer water is pushed up, where it cools, and then circulated down again.

However, since Enceladus is still significantly different from Earth, it is not yet clear whether its oceans can be similar to Earth’s in other characteristics. For example, the depth of the Earth’s oceans is on average is 3.7 km, and the depth of the oceans of Enceladus is at least 30 kilometers. And while they are still covered with a 20-kilometer layer of ice.

Although we cannot see what the ocean is hiding, the ice leaves us with some clues. We know that the ice at the poles is much thinner than at the equator, and even thinner at the south pole, where geysers are erupting. According to a team of researchers led by geophysicist Ana Lobo of the California Institute of Technology, something more complex is happening in the ocean of Enceladus than just vertical convection.

Thin ice is likely associated with stronger melting (thanks, cap!), And thicker ice with more freezing.

This means that where the ice is thicker, the ocean is saltier, since only water freezes, and most of the salts return back to the water. This makes the water under the ice denser, so it sinks to the bottom of the ocean.

In melting regions, the opposite happens. The water is fresher, less dense, so it stays at the top. On Earth, this leads to the emergence thermohaline circulation (she is often called ocean conveyor). Water freezes at the poles, and denser and saltier water sinks to the bottom and flows towards the equator, while warmer waters from the equator are directed to the poles, where they freeze, resulting in a sinking of denser, colder salt water, and so on. …

The team developed computer model of Enceladusbased on our understanding and representation of such currents. It was found that such circulation can form the thickness of the ice, which we just observe on the satellite.

It is still unclear if there is life on Enceladus. It is very far from the Sun, but due to internal geothermal heating, it can have chemosynthetic food webssimilar to those found around hydrothermal vents in the deep zones of the Earth’s oceans. If life lurks in the oceans of Enceladus, the team’s discoveries will help us find it.

For those who, like the translator of this article, see the word chemosynthetic for the first time

Autotrophic organisms, or autotrophs, are able to independently create organic substances from mineral components. Such organisms are also divided into 2 groups: photosynthetics (photoautotrophs) and chemosynthetics (chemoautotrophs). Photosynthetics use the energy of light rays, and chemosynthetics use the energy of chemical bonds of inorganic substances.

We know that the waters of Enceladus are salty: the water taken by the Cassini from the geysers has proven this. If the research team was not mistaken, the salt levels in these geysers may actually be lower as they are ejected from the melting area. It turns out that the water at the equator may be saltier.

We also know that ocean currents on Earth play a special role in the distribution of nutrients. Knowing about the salinity of water and the distribution of nutrients will help us identify those areas of Enceladus that will be most suitable for life (as we understand it now).

At the time of this writing, there is no information about special missions to Enceladus… However, the mission Dragonfly to the moon of Saturn Titanium, Europa Clipper to Jupiter’s moon Europa to study its icy surface, (possibly) spewing fountains of water and steam, as well as the JUpiter ICy Moon Explorer mission (JUICE) could shed light on ocean circulation in these strange ice worlds.

Team research published in the journal Nature geoscience

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