While Europa, Jupiter’s minor moon, is considered one of the most promising options in our search for extraterrestrial life within the solar system itself, a new study has moderated that enthusiasm.
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[EN VIDÉO] Europa, a habitable moon in the solar system Europa is one of the four major moons of Jupiter. It protects an ocean of icy waters, …
Among the stars that could potentially harbor even very primitive life, Europa ranks prominently. For if the frozen surface were completely hostile, the ocean of liquid, salty water beneath this thick crust of ice would present all the necessary and essential properties for the development of biological activity: liquid water, nutrients from interactions between the crust and this occult ocean, and the heat emanating from many submerged volcanoes. A scheme that can ultimately be overly optimistic.
At least that’s the conclusion of a new article published in the journal Science advances. Based on numerical models, a team of researchers has already reproduced the conditions for Europa’s thermal evolution, and their consequences for the dynamics and habitability of this young moon.
A frozen moon outside…and inside
Based on data reported by the Galileo mission, previous studies hypothesized that, like Earth, Europa was a distinct star composed of a metallic core and an anhydrous (without water) silicate mantle. This differentiation would have occurred either at the very moment of satellite formation by accretion, or very shortly thereafter.
However, the results of this new study point to an entirely different scenario. It does indeed appear that Europa formed at much lower temperatures than previously thought. The temperatures would have been between -70 and +30 degrees Celsius. As a result, Jupiter’s moon would have completed its accretion phase before it differentiated, forming a metallic core that required much higher temperatures.
At first, Europe consisted of only one homogeneous layer consisting of a mixture of water ice and / or hydrated silicate rocks, that is, containing hydrogen and oxygen. It is the drying of silicates, under the influence of metamorphism, that would then give rise to an ocean of liquid water covering the surface of the moon, and its icy crust.
Not enough heating to support good living conditions?
As for the nucleus, scientists question its current existence. If it really did exist, it would only have formed much later, several billion years after the formation of the satellite! For the researchers, it is indeed possible that Europa’s internal heat was never sufficient to allow the formation of a metallic core. In question, the very low mass of this small moon, which is only one percent of Earth’s mass.
However, if this energy is lacking in the formation of the core, this calls into question the presence of intense volcanic and hydrothermal activity at the level of the ocean floor. Thus, the geochemical exchanges between rocks and water, favored mainly by hydrothermals of magmatic origin, will be much weaker than previously thought. These results indicate that the supply of nutrients and heat would thus be rather low, thus altering the habitation conditions required for the potential evolution of the Eurosphere biosphere.
A hypothesis that will be based on future data reported by Europa Clipper, NASA’s next probe to reach Jupiter’s moon in 2030 (launch scheduled for October 2024).