Scientists have long speculated that Juptiter’s moon Europa has an icy crust covering a vast, global ocean –what Caltech’s Mike Brown describes as a “miniature Earth” ocean. Undersea volcanoes may result from the melting of the rocky layer beneath.
“Whales of Europa”
Europa’s ocean, some 15 miles below its chaotic terrain of the surface lies the rocky sea floor, with plate tectonics, continents, deep trenches, and active spreading centers, says Caltech’s Brown. “Think about mid-ocean ridges on Earth,” he says, “with their black smokers belching scalding nutrient-rich waters into a sea floor teeming with life that is surviving on these chemicals. It doesn’t take much of an imagination to picture the same sort of rich chemical soup in Europa’s ocean leading to the evolution of some sort of life, living off of the internal energy generated inside of Europa’s core. If you’re looking for Europa’s whales – which many of my friends and I often joke that we are – this is the world you want to look for them.”
Hydrothermal Vents
Underwater volcanoes, if present, could power hydrothermal systems like those that fuel life at the bottom of Earth’s oceans. When seawater comes in contact with hot magma on Earth, it produces chemical energy. These hydrothermal systems produce chemical energy, not sunlight, which helps sustain life deep within our oceans. Volcanic activity on Europa’s seafloor would be one way to support a potential habitable environment in that moon’s ocean.
Existence of Protocells
“New Evidence” -Origin of Life in Deep-Sea Hydrothermal Vents
In 2019, a University College London (ULC)-led research team added to evidence that the origin of life could have been in deep-sea hydrothermal vents rather than shallow pools by creating protocells in hot, alkaline seawater –protocells are seen as a key stepping stone to the development of cell-based life—in such environments, the ULC study found that heat and alkalinity might be necessary to get life started. Some of the world’s oldest fossils discovered originated in such underwater vents
“There are multiple competing theories as to where and how life started. Underwater hydrothermal vents are among most promising locations for life’s beginnings—our findings now add weight to that theory with solid experimental evidence,” said the ULC study’s lead author, evolutionary biochemist Nick Lane.
“Our findings provide additional evidence that Europa’s subsurface ocean may be an environment suitable for the emergence of life,” said lead author Marie Běhounková, referring to new research that models in detail how Europa’s rocky part may flex and heat under the pull of Jupiter’s gravity. It shows the heat that is dissipated and the melting of the rocky mantle. This increases the possibility of volcanic eruptions at the seafloor.
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“Europa is one of the rare planetary bodies,” Běhounková added, “that might have maintained volcanic activity over billions of years, and possibly the only one beyond Earth that has large water reservoirs and a long-lived source of energy.”
NASA’s upcoming Europa Clipper mission, targeting a 2024 launch, will swoop close to the icy moon and collect measurements that may shed light on the recent findings.
3D modeling of Europa’s internal heat
Scientists believe that Europa harbours an immense ocean between its icy crusts and rocky interior. “The water ocean of Europa is generally believed (not only in our work) to be global — extending to the polar areas,” wrote Běhounková in reply to an email from The Daily Galaxy. “The arguments supporting the global ocean usually involve global energy and heat transfer considerations and evidence of the ice shell’s mechanical decoupling (for example, making possible a slightly faster rotation of the ice shell compared to the interior).”
This new research shows how the moon might have enough internal heat that it can partially melt this rock layer. This could allow for the creation of ocean floor volcanoes. This 3D model of how the internal heat is generated and transferred to the moon is the most comprehensive and detailed examination of this effect on the moon.
Volcanic activity most likely to occur near Europa’s poles
The key to Europa’s rocky mantle being hot enough to melt lies with the massive gravitational pull Jupiter has on its moons. As Europa revolves around the gas giant, the icy moon’s interior flexes. The flexing forces energy into the moon’s interior, which then seeps out as heat (think of how repeatedly bending a paperclip generates heat). The more the moon’s interior flexes, the more heat is generated.
Since decades, the topic of volcanoes on Europa has been a hot topic. By comparison, Jupiter’s moon Io is obviously volcanic. Hundreds of volcanoes there erupt lava fountains and eject volcanic gas and dust up to 250 miles (400 kilometers) high—activity that is due to the same kind of internal heating caused by Jupiter’s pull. However, Europa is much closer to Io than Io and scientists wonder if the effect is similar below the icy surface.
Led by Marie Běhounková of Charles University in the Czech Republic, the authors further predicted that volcanic activity is most likely to occur near Europa’s poles—the latitudes where the most heat is generated. They also explored how volcanic activity could have changed over time. The potential for life to have been developed is greater with long-lasting energy sources.
Europa Clipper achieves its goal in 2030
NASA scientists will have an opportunity to test the new predictions when Europa Clipper hits its target in 2030. The spacecraft will orbit Jupiter, and fly close to Europa to map and examine the moon’s composition. Among the science data it collects, the spacecraft will survey the surface in detail and sample the moon’s thin atmosphere.
Scientists believe that seawater could be left on the surface by the ocean-crust exchange. Scientists believe that the exchange could produce gas and even plumes water vapor with ejected particles which could contain materials from the seafloor.
As Europa Clipper measures the moon’s gravity and magnetic field, anomalies in those areas, especially toward the poles, could help confirm the volcanic activity predicted by the new research.
“The prospect for a hot, rocky interior and volcanoes on Europa’s seafloor increases the chance that Europa’s ocean could be a habitable environment,” said Europa Clipper Project Scientist Robert Pappalardo of NASA’s Jet Propulsion Laboratory in Southern California. “We may be able to test this with Europa Clipper’s planned gravity and compositional measurements, which is an exciting prospect.”
Avi ShporerResearch Scientist, MIT Kavli Institute for Astrophysics and Space Research via JPL Marie Běhounková.
Image credit: NASA, Europa Clipper Mission
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Avi Shporer Research Scientist, MIT Kavli Institute for Astrophysics and Space Research. A Google ScholarAvi was once a NASA Sagan Fellow at the Jet Propulsion Laboratory (JPL). His motto, not surprisingly, is a quote from Carl Sagan: “Somewhere, something incredible is waiting to be known.”
