Europa's ocean may support life

A study comparing the ocean of Jupiter's moon Europa with the ocean on Earth has revealed the two are more similar than expected, and that the former may have the necessary chemical balance to support life.

Artist’s impression of NASA’s Europa mission spacecraft, due for launch in the 2020s, that would orbit and investigate Jupiter’s moon
Credit: NASA/JPL-Caltech

Jupiter’s moon Europa may contain the necessary chemical balance to support life, according to a NASA study.

Europa is thought to contain an ocean of salty liquid water under its icy crust, and it’s here that scientists are looking for evidence of the ability to support life. The study has analysed how Europa’s rocky interior could be more similar to Earth’s than initially thought, and how hydrogen might be produced in the moon’s ocean as salt water reacts with the rock.

Scientists at the Jet Propulsion Laboratory have been comparing Europa’s potential for producing hydrogen and oxygen with that of Earth, and found that the two could be comparable in scale, with oxygen production about ten times higher than hydrogen production on both worlds. The balance of these two elements is a key property for sustaining life as we know it.

The process for producing hydrogen involves water trickling into cracks in Europa’s seafloor and reacting with minerals there. Cracks may be opening up at the bottom of Europa’s ocean as its interior continues to cool, after its formation billions of years ago. This would expose new areas of rock to the salt water and cause more hydrogen-producing reactions.

These reactions are similar to those that occur on Earth’s oceanic crust, where cracks are believed to reach depths of 5 to 6 kilometres. On Europa, the cracks could reach as deep as 25 kilometres.

Providing the second part of the chemical balance, oxygen may be produced in Europa’s ocean as radiation from Jupiter splits water ice molecules on the moon’s surface and cycles oxidants back into the ocean. The balance of hydrogen and oxygen created by these processes may be enough to support oceanic life.

"We're studying an alien ocean using methods developed to understand the movement of energy and nutrients in Earth's own systems,” says Steve Vance, planetary scientist at JPL and lead author of the study. “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 as it is on Earth."

Front image: A remastered view of Europa created from images taken by NASA’s Galileo spacecraft in the 1990s.
Credit: NASA/JPL-Caltech/SETI Institute
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