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Looking for Life

In a finding relevant to the search for life in our solar system, researchers at the University of Texas at Austin’s Institute for Geophysics, the Georgia Institute of Technology and the Max Planck Institute for Solar System Research showed that the subsurface ocean on Jupiter’s moon Europa may have deep currents and circulation patterns with heat and energy transfers capable of sustaining biological life.

Scientists believe Europa is one of the planetary bodies in our solar system most likely to have conditions that could sustain life, an idea reinforced by magnetometer readings from the Galileo spacecraft detecting signs of a salty, global ocean below the moon’s icy shell.

Without direct measurements of the ocean, scientists have to rely on magnetometer data and observations of the moon’s icy surface to account for oceanic conditions below the ice.

Regions of disrupted ice on the surface, known as chaos terrains, are one of Europa’s most prominent features. As lead author Krista Soderlund and colleagues explained in the online edition of the journal Nature Geoscience, the chaos terrains, which are concentrated in Europa’s equatorial region, could result from convection in Europa’s ice shell, accelerated by heat from the ocean. The heat transfer and possible marine ice formation may be helping form diapirs, or warm compositionally buoyant plumes of ice that rise through the shell.

In a numerical model of Europa’s ocean circulation, the researchers found that warm rising ocean currents near the equator and subsiding currents in latitudes closer to the poles could account for the location of chaos terrains and other features of Europa’s surface. Such a pattern coupled with regionally more vigorous turbulence intensifies heat transfer near the equator, which could help initiate upwelling ice pulses that create features such as the chaos terrains.

“The processes we are modeling on Europa remind us of processes on Earth,” said Soderlund, referring to a similar process that has been observed in the patterns creating marine ice in parts of Antarctica.