Ocean on Jupiter’s Moon Europa ‘Could Be Habitable’

Europa, one of Jupiter’s 78 known moons. (Photo by NASA / JPL-Caltech / SETI Institute)

(CN) — We may not have to go far in our search for extraterrestrial life: Researchers at NASA have uncovered new data that life may have the potential to exist in the oceans of Jupiter’s moon Europa.

Europa has for years been considered an ideal destination to search for signs of life. With its oceans, tidal activity and plate tectonics, it meets a few of the prerequisites right off the bat. A new study led by Dr. Mohit Melwani Daswani seeks to uncover Europa’s geochemical makeup, along with the origin story behind its oceans.

Researchers from NASA’s Jet Propulsion Laboratory in Pasadena used data from the Galileo spacecraft to model geochemical reservoirs within the interior of Europa to search for the conditions necessary to support life.

Much of what we know about the Jovian system comes from flybys of the Voyager and Galileo spacecrafts, launched by NASA in 1979 and 1989, respectively. The Juno spacecraft flew by more recently, in 2016, taking detailed photos of the gas giant on its way to study Pluto.

Europa is one of the largest moons in our solar system. Discovered by Galileo Galilei in 1610, it’s 1,900 miles in diameter — smaller than Earth’s moon — but larger than the dwarf planet Pluto. Its exterior is made of solid ice between two and 20 miles thick, floating on an interior ocean approximately 60 miles deep. The surface temperature never rises above minus 260 degrees Fahrenheit at the equator, and minus 370 degrees Fahrenheit at the poles. It’s frigid, to say the least. It’s also one of the most reflective objects in our solar system thanks to that icy shell.

According to Melwani Daswani, these oceans may have been formed by the dehydration of water-rich minerals found within its interior. These water-rich minerals may have dried out due to heat caused by the decay of radioactive elements early in Europa’s history, as well as the effect of tides caused by Europa’s interaction with Jupiter and its 78 other known moons. This process, known as metamorphism, may be the driving force behind the formation of other ocean worlds in our solar system and beyond.

“Europa’s ocean could be kept in a liquid state by its tidal interactions with its neighbors Io and Ganymede, and Jupiter,” said Melwani Daswani. “The availability of liquid water is the first step to habitability. In addition, chemical exchange between the ocean and the rocky interior may have been significant in the past so potential life may have been able to use chemical energy to survive. We have not figured out whether chemical exchange and potential habitability extends to the present, but it is the next step in our research.”

Europa is thought to contain over twice the volume or water found on Earth. Despite the inhospitable surface temperatures, scientists think its inner ocean could be quite a bit warmer due to the thermal vents in its mantle layer releasing heat from an iron core, similar to what happens on Earth.

Scientists originally believed water on Europa would be mildly acidic, and concentrated with carbon dioxide, calcium and sulfate stemming from these suboceanic vents.

“Indeed it was thought that this ocean could still be rather sulfuric” added Melwani Daswani “but our simulations, coupled with data from the Hubble Space Telescope, showing chloride on Europa’s surface, suggest that the water most likely became chloride rich. In other words, its composition became more like oceans on Earth. We believe that this ocean could be quite habitable for life.”

The next decade holds promise for more fascinating discoveries on the moons of Jupiter. NASA’s Europa Clipper mission will launch in the next few years to follow up on the giant water plumes observed by the Hubble Space Telescope shooting above Europa’s surface. If scientists can locate these plumes it may become easier to analyze and study the chemical composition of Europa’s oceans. The alternative would be drilling through miles of ice to launch a robotic submarine — an intriguing but substantially riskier and more expensive endeavor.

The European Space Agency has its own mission planned for launch in 2022 to study the organic molecules believed to exist on Europa for clues to the existence of life. The European mission will also study two other Galilean moons, Ganymede and Callisto, both believed to have oceans of their own.

“Europa is one of our best chances of finding life in our solar system,” Melwani Baswani said.

Melwani Baswani will present these findings at the annual Goldschmidt conference, the world’s main geochemistry summit, hosted by the Geochemical Society and the European Association of Geochemistry.

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