The ice-encrusted moon of Jupiter Europa is becoming more and more like the greatest spot in the Solar System to seek for alien life.
According to new research, the rocky mantle deep under the heavy ice and salty ocean might be hot enough to support volcanic activity. Furthermore, it might have been as hot during the majority of its 4.5-billion-year existence. The discovery has immediate ramifications for the existence of life on Europa’s bottom.
“Our results contribute to the growing body of evidence suggesting Europa’s subsurface ocean might be a viable setting for the origin of life,” said geophysicist Marie Bhounková of Czechia’s Charles University.
“Europa is one of the few planetary bodies that might have sustained volcanic activity for billions of years, and it’s possible that it’s the only one beyond Earth with vast water reserves and a long-lasting supply of energy.”
You would think that an ice planet distant from the Sun’s life-sustaining warmth – where surface temperatures may reach -140 degrees Celsius (-225 degrees Fahrenheit) – would be an odd location to discover life, but there is precedent right here on Earth.
True, the majority of life here is dependent on a photosynthesis-based food chain… However, life has found a way in certain extreme situations where the Sun never shines.
Volcanic vents bleed heat into the waters surrounding them in the dark depths of the ocean, too deep for sunlight to reach. There, life is based on chemosynthesis, microorganisms that make food by harnessing the energy contained in geochemistry rather than solar energy. Bacteria attract other species that can consume them, resulting in the formation of a complex ecosystem down there in the dark.
We know Europa has a worldwide ocean under its thick ice shell because liquid water has been spotted bursting out of breaches in the ice in the form of geysers. We’ve also found what seems to be salt. This clarifies some of the known criteria for chemosynthetic hydrothermal life.
What we don’t know is if Europa’s seabed contains volcanic activity that opens into vents as it does on Earth.
It’s conceivable; Jupiter’s moon is one of the planet’s moons. Because of the continual strains put on the interior by Jupiter’s gravitational dragging (and potentially the gravitational pulling of the other Jovian moons), Io is the most volcanic globe in the Solar System.
However, since Europa is further away from Jupiter than Io, there is still some dispute, therefore Bhounková and her colleagues decided to investigate.
They employed comprehensive modeling to describe the history and heating of Europa’s interior since its creation. They discovered various systems at work that might be keeping the planet from entirely freezing over. To begin with, heat emitted by radioactive decay of materials in Europa’s mantle is thought to have provided a considerable portion of the moon’s interior heat, particularly early in its existence.
The fluctuating stresses induced by tidal pressures imposed by Europa’s elliptical orbit around Jupiter, on the other hand, should have caused continual bending in the moon’s interior throughout time.
This stretching generates heat, which should be sufficient to melt rock into magma, resulting in volcanic activity that may still be occurring now, particularly at higher latitudes near the poles.
Scientists may now hunt for traces of this activity when probes like NASA’s Europa Clipper and the European Space Agency’s JUpiter ICy moons Explorer (JUICE) mission (scheduled to launch in 2024 and next year, respectively) approach near to Europa.
The abnormal abundance of hydrogen and methane in Europa’s thin atmosphere might be the consequence of chemical processes happening at hydrothermal vents, and gravitational anomalies might indicate the existence of deep magmatic activity. Fresh marine sediments deposited on Europa’s surface might also suggest subterranean activity.
“The possibility of a hot, rocky interior and volcanoes on Europa’s seabed improves the probability that Europa’s ocean may be a habitable environment,” said NASA’s Jet Propulsion Laboratory’s Europa Clipper Project Scientist Robert Pappalardo, who wasn’t involved in the study.
“With Europa Clipper’s anticipated gravity and compositional observations, we may be able to test this, which is a fascinating possibility.”
We’ll have to wait a few more years for the spaceship to arrive, however. The tyranny of distance, how I despise it!
The team’s findings were published in the journal Geophysical Research Letters.