Washington DC: It may be lacking volcanic hydrothermal activity, but Jupiter's moon Europa's ocean may have an Earth-like chemical balance that could sustain life, suggests a new study.


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Europa is strongly believed to hide a deep ocean of salty liquid water beneath its icy shell. Scientists at NASA's Jet Propulsion Laboratory (JPL) compared the ocean's potential for producing hydrogen and oxygen with that of Earth, through processes that do not directly involve volcanism. The balance of these two elements is a key indicator of the energy available for life.


The study found that the amounts would be comparable in scale; on both worlds, oxygen production is about 10 times higher than hydrogen production.


The work draws attention to the ways that Europa's rocky interior may be much more complex and possibly Earth-like than people typically think, according to lead author Steve Vance. "The cycling of oxygen and hydrogen in Europa's ocean will be a major driver for Europa's ocean chemistry and any life there, just it is on Earth."


Co-author Kevin Hand noted that the oxidants from the ice are like the positive terminal of a battery and the chemicals from the seafloor, called reductants, are like the negative terminal. "Whether or not life and biological processes complete the circuit is part of what motivates our exploration of Europa."


According to Vance, researchers previously speculated that volcanism is paramount for creating a habitable environment in Europa's ocean. If such activity is not occurring in its rocky interior, the thinking goes, the large flux of oxidants from the surface would make the ocean too acidic, and toxic, for life. "But actually, if the rock is cold, it's easier to fracture," he said. "This allows for a huge amount of hydrogen to be produced by serpentinization that would balance the oxidants in a ratio comparable to that in Earth's oceans."


The study is published in Geophysical Research Letters .