4 December 2013
Europa report: moon's ocean currents make life possible
by Will Parker
A team of scientists who have been modeling the subsurface ocean on Jupiter's moon Europa say that the ocean's deep currents and circulation patterns likely create heat and energy transfers capable of sustaining biological life. The researchers behind the exciting new finding, from the University of Texas at Austin, the Georgia Institute of Technology, and the Max Planck Institute for Solar System Research, have published their work in Nature Geoscience.
Working out what sort of conditions exist below Europa's icy shell is a tricky business, with researchers relying on magnetometer readings from the Galileo spacecraft to construct models of the subsurface ocean.
To better predict possible currents and energy transfers in the ocean, the researchers turned their attention to the regions of disrupted ice on the moon's surface known as chaos terrains. "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," explained lead author Krista Soderlund, from the University of Texas. "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 computer 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," says Soderlund, who notes that a similar process has been observed in the creation of marine ice in Antarctica.
"This tells us foundational aspects of ocean physics," said co-author Britney Schmidt, from the Georgia Institute of Tech. More importantly, she adds, 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," says Schmidt, "all of which makes us think about the possibility of life on Europa."
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