Jupiter’s moon Europa harbors underneath a tectonically modified ice shell a salty ocean in direct contact with its rocky interior. Such an oceanic environment makes the icy moon a primary target for the search of a habitable world outside the Earth. The occurrence of magmatic activity on the seafloor is essential to determine if it constitutes an environment hospitable to life. A new study, published in the journal Geophysical Research Letters, shows how the icy moon may have enough internal heat to partially melt the rocky layer, a process that could feed volcanoes on the ocean floor. The 3D modeling of how this internal heat is produced and transferred is the most detailed and thorough examination yet of the effect this interior heating has on the moon.
The surface of Europa looms large in this newly-reprocessed color view; image scale is 1.6 km per pixel; north on Europa is at right. Image credit: NASA / JPL-Caltech / SETI Institute.
Volcanic activity on Jupiter’s moon Europa has been a topic of speculation for decades.
By comparison, Jupiter’s moon Io is obviously volcanic. Hundreds of volcanoes there erupt lava fountains and eject volcanic gas and dust up to 400 km (250 miles) high — activity that is due to the massive gravitational pull Jupiter has on its moons.
But Europa is farther away than Io is from its host planet, so planetary scientists have wondered whether the effect would be similar under the icy surface.
The new research models in detail how Europa’s rocky part may flex and heat under the pull of Jupiter’s gravity.
It shows where heat dissipates and how it melts that rocky mantle, increasing the likelihood of volcanoes on the seafloor.
“Our findings provide additional evidence that Europa’s subsurface ocean may be an environment suitable for the emergence of life,” said Dr. Marie Běhounková, a researcher at Charles University.
The interior of Europa may consist of an iron core, surrounded by a rocky mantle in direct contact with an ocean under the icy crust; Běhounková et al. modeled how internal heat may fuel volcanoes on the seafloor. Image credit: NASA / JPL-Caltech / Michael Carroll.
Using a three-dimensional numerical model, Dr. Běhounková and colleagues demonstrated that the volcanic activity can continue during most of Europa’s history even though it progressively decays as the interior cools down. Long-lived energy sources give more opportunity for potential life to have developed.
They also predicted that volcanic activity is most likely to occur near Europa’s poles — the latitudes where the most heat is generated.
Underwater volcanoes, if present, could power hydrothermal systems like those that fuel life at the bottom of Earth’s oceans.
On Earth, when seawater comes into contact with hot magma, the interaction results in chemical energy.
And it is chemical energy from these hydrothermal systems, rather than from sunlight, that helps support life deep in our own oceans.
Volcanic activity on Europa’s seafloor would be one way to support a potential habitable environment in that moon’s ocean.
“Europa is one of the rare planetary bodies 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,” Dr. Běhounková said.
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Marie Běhounková et al. Tidally Induced Magmatic Pulses on the Oceanic Floor of Jupiter’s Moon Europa. Geophysical Research Letters, published online December 22, 2020; doi: 10.1029/2020GL090077
