The fact that Jupiter’s moon Europa contains a salty ocean under a layer of ice of several kilometers is generally accepted by researchers. It’s not entirely clear what form the salt crystals recently discovered on the surface of the moon by the Hubble Space Telescope were, but the new results may shed some light, at least until the new planned missions to Jupiter, which will also fly by Europa. , can make more light in this case.

We all know that salt significantly lowers the freezing point of water (which is why salt is effective in winter, when we want to defrost snowy roads), which means that there is not much salt ice on Earth: the natural conditions on our planet do not allow the formation of frozen water that contains in its crystalline structure is sodium chloride (the same substance we use in the kitchen to make food taste better).

However, under special conditions of temperature and pressure, an aqueous solution that also contains sodium chloride (table salt) can become solid: in this case, we will have crystals that, in addition to sodium and potassium, will include water molecules in their structure. An important characteristic of these crystals is that they continue to retain their shape even if the special conditions under which they were formed disappear.

In 2019, data obtained by the Hubble Space Telescope hinted at the presence of sodium chloride in colored structures on the surface of Europa. Most likely, the salt water released from its depths reaches the surface of Jupiter’s moon through geysers, after which, after sublimation of the water (due to the temperature and pressure conditions on Europa), the salt crystals remain on the surface and can thus be identified with advanced scientific instruments.

The researchers are not sure if the compound is similar to table salt or if it is hydrated salt crystals, meaning crystals that contain water molecules in addition to sodium and chlorine ions. Two missions are being prepared for Jupiter, during which the satellites of the largest planet of the Solar System will be explored: on April 13, the Ariane 5 rocket will launch the JUICE (Jupiter Icy Moons Explorer) European probe from French Guiana. ), which will be the penultimate launch of a European rocket before it is replaced by Ariane 6.

The JUICE probe will enter Jupiter orbit in 2031, from where it will make a series of flybys of the moons Ganymede, Callisto and Europa, and then from 2034 it will enter orbit around Ganymede (it will be the first interplanetary probe to do so).

The probe will carry at least 12 scientific instruments, making it the most extensive survey ever conducted in the Jupiter system (that is, the region around the planet Jupiter). Next year, the Falcon Heavy rocket will launch the American Europa Clipper probe to Jupiter, and in 2030 it will enter the orbit of the planet, from where it will fly by the moon Europa twice with JUICE, before also landing on the orbiting Ganymede.

It’s possible that after 2025, NASA will use the SLS rocket to send a new probe, this time directly to Europa, to land on the surface of Jupiter’s moon and look for signs of life. That’s because, in addition to a salty ocean like the one we have on Earth, the gravitational interaction between Europa and Jupiter causes the moon’s core to periodically contract and expand, and this energy is released as heat that warms the interior ocean.

Therefore, the ocean is not only salty, but also has a high temperature of about 0 C, which is 200 degrees higher than the temperature of the satellite’s surface. Although Europa is similar in size to the Moon, the amount of water believed to exist beneath the surface of Jupiter’s moon is roughly twice that of all existing water on Earth.

And that makes Europa one of the favorite destinations when it comes to looking for life outside Earth’s atmosphere, because the moon appears to contain many of the ingredients that were in Earth’s oceans billions of years ago.

And it’s not just Europa that’s in this position, Saturn’s moon Enceladus is also on the short list of places in the Solar System where life could exist in a warm, salty ocean. Unfortunately, we will have to endure several more decades until interplanetary probes can closely study the oceans of these alien worlds.

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