While Europa, the small moon of Jupiter, is considered one of the most promising options in our search for extraterrestrial life in the solar system itself, a new study has tempered that enthusiasm.
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[EN VIDÉO] Europa, a Potentially Habitable Moon in the Solar System Europa is one of Jupiter’s four main moons. It houses an ocean of icy waters…
Among the stars that are likely to host even the most primitive life, Europa occupies a prominent position. Because if the frozen surface were completely hostile, the ocean of salty, liquid water that is under this thick icy crust would have all the necessary and essential properties for the development of biological activity: liquid water, nutrients from reactions between the crust and it hidden ocean and the heat given off by a multitude of submarine volcanoes. A plan that might end up being a bit too optimistic.
At least that’s the conclusion of a new article published in the journal Science Advances. Indeed, based on numerical models, a team of researchers has reproduced the conditions of Europa’s thermal evolution and their impact on the dynamics and habitability of this small moon.
A frozen moon outside… and inside
Based on the data reported by the Galileo mission, previous studies had assumed that Europa, like Earth, was a differentiated star composed of a metallic core and a mantle of anhydrous silicates (without water). This differentiation would have taken place either at the very moment of the formation of the satellite by accretion, or very shortly thereafter.
However, the results of this new study suggest a very different scenario. Indeed, it appears that Europa formed at much lower temperatures than previously thought. Temperatures that would have been around -70 to +30°C. As a result, Jupiter’s moon would have completed its accretion phase before it differentiated, requiring much higher temperatures to form a metallic core.
In the beginning, therefore, Europa would have consisted of only a single homogeneous layer consisting of a mixture of water ice and/or hydrated silicate rocks, i.e. containing hydrogen and oxygen. It is the dehydration of silicates under the influence of metamorphism that would then have resulted in the ocean of liquid water that covered the moon’s surface and its icy crust.
Not enough heat to ensure good living conditions?
As for the core, scientists even doubt its current existence. If it actually exists, it would have formed very late, several billion years after the formation of the satellite! Indeed, according to the researchers, it is possible that Europa’s internal heat was never sufficient to allow the formation of a metallic core. The very small mass of this small moon, which makes up only one percent of the earth’s mass, is questionable.
However, if this energy was lacking for the formation of a core, this puts into question the existence of intense volcanic and hydrothermal activity at the seafloor level. The geochemical exchange between rock and water, which is mainly favored by hydrothermalism of magmatic origin, would therefore be much weaker than previously thought. These results indicate that the supply of nutrients and heat would therefore be rather low and that the living conditions would change, which would be necessary for a possible development of a biosphere in the European ocean.
A hypothesis that will be the subject of future data reported by Europa Clipper, the next NASA probe that will reach Jupiter’s moon in 2030 (launch scheduled for October 2024).