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| A “black smoker” at the Piccard hydrothermal field, 5,000 meters below the surface, on the Mid-Cayman Rise. Photo Credit: Chris German / ROV Jason, ©WHOI, 2012 |
The giant planet Jupiter has nearly 100 known moons, but none have captured the imagination of scientists quite like Europa. Scientists suspect Europa has a salty ocean beneath its icy crust, holding twice as much water as all of Earth's oceans combined. For decades, scientists have wondered whether that ocean could harbor the right conditions for life, placing Europa near the top of the list of solar system bodies to explore.
A new study, led by Washington University and involving Woods Hole Oceanographic Institution (WHOI), indicates it may lack modern-day tectonic activity at the seafloor that sheds new light on this topic. Using models that account for Europa’s size, rocky core, and Jupiter’s gravity, the team concludes that the moon likely lacks the tectonic activity, or seafloor volcanism, that gives rise to dramatic “black smoker” hot springs on Earth.
“Our study shows that there might not be a lot happening down there, from a geophysical perspective,” said Chris German, WHOI senior scientist and co-author of the new study.
Beneath Europa’s ice and ocean is a rocky interior, not unlike Earth’s, but this study indicates that Europa’s core should have long since cooled, more like Earth’s present-day Moon.
“What our work at WHOI has shown is that so long as Europa’s seafloor has been geologically active in the past,” German continued. “It could still have more than enough capacity to host lower-temperature forms of fluid flow, also well-known on Earth, that could underpin a geothermally-driven food chain.”
With no way to physically explore the moon’s seafloor, researchers had to combine known facts about Europa with inferences drawn from the geology of Earth and other bodies.
“Europa likely still has some tidal heating, which is why it isn’t completely frozen, and it may have experienced much more heating in the distant past,” said Paul Byrne, lead author of the study and an associate professor of Earth, environmental, and planetary sciences at Washington University. “But we don’t see much evidence of active geology on Europa’s icy surface today. Our calculations suggest that the geological processes operating at the seafloor, considering tides, long-term interior cooling, and mantle convection, aren’t strong enough to drive significant activity right now.”
The findings from this study feed directly into a new five-year, $5 million NASA project that WHOI has been selected to lead. Investigating Ocean Worlds brings together experts from 16 U.S. laboratories to study how organic compounds are generated and altered as they move through an ocean world’s subseafloor, and how those compounds may continue to evolve as they travel upward through the ocean and onto the icy surface, where future spacecraft could detect them.
“One of the core components of that new project, inspired by this work, will be an investigation of fluids circulating at lower temperatures beneath the seafloor of an Ocean World like Europa,” German said. “We will investigate how these fluids continue to release nutrients, synthesize organic molecules and, perhaps, even host primitive microbial life, just as they do here in Earth’s deep oceans.”
“This is an exciting time to be starting the next stage of our investigations,” he continued. “By 2031, when the Europa Clipper begins flybys of that moon, we plan to have much more information available to help interpret the precise measurements of its ice caps and oceans that the spacecraft will make. We plan to be ready.”
Title: Little to no active faulting likely at Europa’s seafloor today
Authors: Paul K. Byrne, Henry G. Dawson, Christian Klimczak, Paul V. Regensburger, Kelsey T. Crane, Jeffrey G. Catalano, Catherine M. Elder, Bradford J. Foley, Christopher R. German, Austin P. Green, Douglas J. Hemingway, Mohit Melwani Daswani, Mark P. Panning, Noah Randolph-Flagg, Barbara Sherwood Lollar, Philip Skemer, Steven D. Vance, and Douglas A. Wiens
Source/Credit: Woods Hole Oceanographic Institution
Reference Number: ps010626_01
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