Ocean Currents Shape Europa's Icy Shell in a Manner That Support Life

Jupiter's sixth closet moon, Europa, was earlier considered as the most potential candidate in our Solar system to accommodate biological organisms. A new finding throws life into this idea, suggesting the subsurface ocean on Jupiter may carry deep currents and circulation patterns with heat and energy transfers capable of sustaining life.

In a new finding the researchers at The University of Texas at Austin's Institute for Geophysics along with the Georgia Institute of Technology and the Max Planck Institute for Solar System Research, have revealed that the ocean currents shape Jupiter's moon icy shell in a manner that is suitable for supporting biological life.

The notion of Europa sustaining life was reinforced by the magnetometer readings provided by the Galileo spacecraft that detected traces of salty, global ocean beneath the icy shell. Due to lack of direct measurements of the ocean beneath the icy shell, scientists depend heavily on the data provided by the magnetometer, including the observations of Europa's icy shell, to get a picture of the ocean conditions beneath the icy surface.

Europa is blanketed with thick layer of ice shell beneath which lies a liquid ocean. The ice shell is marked with areas of disrupted ice called as the chaos terrain that envelops nearly 40 percent of the satellite's surface. This is one of the most prominent features of Europa, and concentrated heavily in the equatorial regions. They are present due to the variation in the ice shell that increases with the ocean's heat. The team also predicts that the transfer of heart and the formation of marine ice helps in formation of diapirs (rock formation), warm compositionally buoyant plumes of ice that emerge through the icy shell.

Through a numerical model constructed of Europa's ocean circulation, the team noticed that the warm ocean currents rising near the equator and dropping currents near the latitudes near the poles may offer strong explanation for the presence of chaos terrains as well as other features on Europa's surface. When the same pattern was exposed to turbulence, the transfer of heat near the equator was intensified, this help in the flow of ice pulses that trigger the formation of chaos terrains.

A similar process has been observed on Earth-in patterns creating marine ice in regions of Antartica.

The current patterns modeled for Europa are distinct with the patterns that were observed on Jupiter and Saturn. In the latter, storms are formed due to the manner in which the atmosphere rotate. They also noticed that the physics of the ocean trapped beneath the icy shell of Europa are more similar to that of the oceans of the ice giants Uranus and Neptune.

"This tells us foundational aspects of ocean physics," notes co-author Britney Schmidt, assistant professor at the Georgia Institute of Technology. "If the study's hypothesis is correct, it shows that Europa's oceans are very important as a controlling influence on the surface ice shell, offering proof of the concept that ice-ocean interactions are important to Europa.  That means more evidence that the ocean is there, that it's active, and there are interesting interactions between the ocean and ice shell all of which makes us think about the possibility of life on Europa."

The researchers plan on testing this hypothesis through future missions to the Jovian system. The findings were published in the journal Nature Geosciences.