Home South pole ice Where do the geysers on the moon Enceladus come from?

Where do the geysers on the moon Enceladus come from?

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Astronomer Rafael Bachiller reveals to us in this series the most spectacular phenomena of the Cosmos. Exciting research topics, astronomical adventures and scientific news about the Universe analyzed in depth.

Saturn’s icy moon Enclado has spectacular geysers that shoot water into space. It was assumed that these geysers originated from an ocean deep below the surface, but a new study now casts doubt on that.

deep ocean

Although measuring only 500 kilometers in diameter (7 times smaller than that of our Moon), the Enclado is one of the most interesting bodies in the solar system. Its surface is very rich, with old areas full of craters and other younger areas renewed by tectonic activity. But what surprises most in this small world are the more than a hundred geysers which, in the area of ​​its south pole, release water vapor into space.

The structure of the enclosureNASA/JPL

These jets were discovered by the Cassini space probe when it flew by the small moon in 2005. Since then, it has been discovered that in addition to water, these plumes also contain ice particles, salt crystals common, ammonia and even some organic compounds. . .

Studies of the structure of this moon, carried out over nearly two decades, have revealed that its surface is a thick crust of ice about 30 to 40 kilometers thick, under which there is a liquid ocean that can reach between 10 and 30 kilometers thick. 30 kilometers deep and finally a rocky core.

Cryovolcanoes

Enclado’s geysers appear to emerge from surface ridges called “tiger stripes”. Until now, these ridges were thought to be geologically similar to Earth’s great mountain ranges and subduction zones, where volcanoes form.

Therefore, these geysers seem to be directly connected to the deep ocean below the surface. Friction from small earthquakes or tectonic activity on the surface of the small moon could melt some of the ice on the surface and create ridged fissures from which geysers would emerge carrying water from the ocean in space.

fit for life

It is still a mystery how the water in this ocean is kept liquid and what is the mechanism by which it is relatively warm. Perhaps the source of energy lies in the strong tidal forces due to the gravitational pull of the giant Saturn.

Be that as it may, this liquid ocean, which must be rich in salts, offers conditions that seem very favorable to the emergence of life. Along with Jupiter’s moons Ganmedes and Europa, which also contain large oceans beneath their surfaces, the Enclado Ocean is one of the most exciting places to search for extraterrestrial life in our solar system.

Until now, it was thought that studying the chemical composition of geysers would reveal the composition of the ocean to which they appeared to be directly connected, offering a clue as to the possible existence of life.

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Planetary scientists Colin Meyer and Jacob Buffo, from Dartmouth College (a private university in New Hampshire, USA), are dedicated to studying and building numerical models to simulate the behavior of land ice and polar seas as well as that of the icy moons of the Sun. system. At a recent meeting of the American Geophysical Union, a team coordinated by these researchers presented simulations which show the possibility that the geysers of the Enclado do not arise directly from the ocean, but can be created in pockets of muddy water on the icy crust. And the chemical processes taking place in the wet mush of these puddles may not be the same as those in the much deeper liquid ocean.

This work therefore constitutes a serious warning as to the conclusions that can be drawn from the properties of geysers. It now seems possible that these properties are not, after all, identical to those of the deep ocean of the Enclado. And this is something that must be taken into account in the design of the many space missions that are under study by different space agencies, such as the North American NASA and the European ESA.

The hope that sampling the water ejected by geysers would be enough to reveal the chemical composition of the ocean, without drilling, may not be entirely justified. If no signs of life were found in the geysers, that didn’t mean they couldn’t be found in the ocean.

Meyer, Buffo and colleagues’ work titled “A Soft Source for Enceladus Geysers” was presented at a recent meeting of the American Geophysical Union held in New Orleans. The abstract of the book can be consulted on this link.

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Rafael Bachiller is director of the National Astronomical Observatory [https://bit.ly/3GzKALD] (National Geographic Institute) and academic of the Royal Academy of Physicians of Spain.