Europa's Subglacial Ocean 'Breathes'
Using the Webb telescope, planetary scientists have recorded for the first time that the icy shell of the moon Europa is actively changing. It turned out that ice is rapidly forming, breaking down, and recrystallizing on its surface. Observations from the NIRSpec infrared spectrometer revealed the so-called Fresnel peak at a wavelength of 3.1 microns, indicating the presence of pure crystalline ice. The Fresnel peak is a characteristic maximum in the reflectance spectrum that appears due to the fact that smooth crystalline ice reflects light of a certain wavelength more strongly than others.
These data confirmed that the upper layer of ice is not static and is renewed in less than 15 days due to internal heat caused by Jupiter's tidal forces.
Spectral analysis showed that fresh ice crystals are present in the Tara Regio and Powys Regio regions, and compounds of NaCl, H₂O₂ and ¹³CO₂ were also detected, which cannot be preserved for long without replenishment from the depths. This indicates the existence of a subglacial ocean up to 30 km deep, which could be potentially habitable.
Laboratory experiments have confirmed that the preservation of crystalline ice is possible only with a constant heat flow from the depths. NASA's Europa Clipper mission, scheduled for launch in 2030, will help to finally confirm the hypothesis of geological activity and a hidden ocean on Europa.