Year: 2018-19
Alex Stefan Balint
School: Colegiul National
City: Iasi
“Europa represents the moon with the highest likelihood of supporting extraterrestrial life, as indicated by the physical characteristics gathered thus far. Although there is no conclusive theory regarding the emergence of life, its main requirements are constituted by water, chemical substances and a source of energy, all present to a certain degree on the target moon.
One decisive factor enabling life is a liquid dispersion medium for molecules to be drawn together and interact with each other. According to the “thick ice” model, resulting from analyzing the energy generated by tidal heating and the fresh ice within craters, the surface should consist of a 10-30 km thick layer of ice followed by approximately 100 km of liquid water. A subsurface ocean is supported by the induced magnetic field from Jupiter, pointing to the existence of an electrically conductive layer, most likely represented by an ocean of liquid saltwater. Additionally, there is a notable difference in the predicted pattern of liniae resulting from tidal flexing and actual physical appearance, which can be explained by non-synchronous rotation and a tilt in its axis. Therefore, the outer ice layer could slide over the inner mantle by virtue of an interposing liquid.
Another noticeable aspect is the possibility of presumed organisms to use tidal flexing available as a source of energy, inducing the movement of chemical substances. Not only does it render the subsurface ocean warmer, but it can also heat the seafloor, enabling hydrothermal processes to take place. In particular, hydrothermal vents could represent a shelter for extraterrestrial life, due to the favorable conditions of temperature merged with the chemical component. In this case, they could provide the necessary environment for abiogenesis, especially if they are primarily alkaline.
According to Michael Russel, this process may take place if the vents are endowed with sulfide compounds, which interacts with the surrounding environment containing iron(II), thereby creating an inorganic compartmentation that would facilitate exchanges between the two mediums and concentrate organic molecules inside.
The characteristics of Europa seem to support this description, since the reddish-brown substances covering the fractures on its surface indicate the presence of Sulphur compounds and Iron(III) oxide. The latter may ensue from Iron(II) sulfide oxidized by hydrogen peroxide in acidic environment, caused by the high surface irradiation (≃5.4Sv/day) creating oxidants. However, the resulting inhospitable acidic environment could be neutralized by serpentinization and the alkaline hydrothermal vents.
A closer investigation of Europa’s characteristics is necessary for an accurate assessment of its habitability potential. Essentially, a future spacecraft should evaluate the chemical composition of vapor plumes at the south pole, searching primarily for amino acids and the prebiotic compounds linked to abiogenesis. Moreover, a lander may drill the surface to examine potential biogenic substances and tholins, possibly finding traces of prokaryotic life. Nevertheless, even yielding a negative result does not definitively exclude the possibility of life on Europa, but would merely confirm our endeavors in comprehending the complex chain of events creating life and represent one step closer to discovering extraterrestrial life."
