Astronomers announced Wednesday that Jupiter’s icy moon, Europa may hold significant quantities of water.
Analysis of the moon’s surface suggests plumes of warmer water well up beneath its icy shell, melting and fracturing the outer layers, scientists said Wednesday. The discovery would be the first such sign of liquid water outside of that seen on planet earth.
The results of the study, published in the journal Nature, find that Europa’s icy shell is upwards of six miles thick, containing large pockets of water — some of which may exist within two miles of the surface. Astronomers have long suspected Europa could hold vast quantities of liquid water.
Drawing from studies of underground volcanoes in Iceland and Antarctica, scientists ran computer models simulating the existing environment on the planet. Scientist estimate that Europa contains roughly enough to fill one of the North American Great Lakes. Additionally, Europa is known to house a vast ocean, with two to three times the volume of Earth’s oceans.
Its white icy shell brightly reflecting the distant Sun, Europa is the second closest satellite of Jupiter, the biggest planet of the Solar System.
Still, scientists involved with the research were hesitant to say whether the discovery of water would lead to the prospect of discovering life.
“One opinion in the scientific community has been, ‘If the ice shell is thick, that’s bad for biology — that it might mean the surface isn’t communicating with the underlying ocean’,” said Britney Schmidt, a geophysicist at the University of Texas at Austin, who led the research.
“Now we’ve found evidence that there are giant liquid lakes perched inside the ice shell,” she added.
However, one of the paper’s members said the discovery could be an indication that life may exist on Europa.
“This creates a potential source of energy for life to tap,” said geophysicist Don Blankenship, a collaborator from the University of Texas.
The study was conducted following new studies of ice formations in Antarctica and Iceland, which have provided clues to how conditions similar to those found on Europa are created. A number of large underground lakes have recently been discovered in Antarctica, leading scientists to posit that similar environments may harbor life on moons or planets in the solar system.
The latest report comes as NASA is set to launch a rover to Mars later this month. The expedition will search for signs of water on the Red Planet, the latest such mission launched by the space agency in recent years. A mission to explore Europa is on the shortlist of candidates for future planetary explorations by
Update: NASA released the following statement in regards to the discovery:
The data suggest there is significant exchange between Europa’s icy shell and the ocean beneath. This information could bolster arguments that Europa’s global subsurface ocean represents a potential habitat for life elsewhere in our solar system. The findings are published in the scientific journal Nature.
“The data opens up some compelling possibilities,” said Mary Voytek, director of NASA’s Astrobiology Program at agency headquarters in Washington. “However, scientists worldwide will want to take a close look at this analysis and review the data before we can fully appreciate the implication of these results.”
NASA’s Galileo spacecraft, launched by the space shuttle Atlantis in 1989 to Jupiter, produced numerous discoveries and provided scientists decades of data to analyze. Galileo studied Jupiter, which is the most massive planet in the solar system, and some of its many moons.
One of the most significant discoveries was the inference of a global salt water ocean below the surface of Europa. This ocean is deep enough to cover the whole surface of Europa and contains more liquid water than all of Earth’s oceans combined. However, being far from the sun, the ocean surface is completely frozen. Most scientists think this ice crust is tens of miles thick.
“One opinion in the scientific community has been if the ice shell is thick, that’s bad for biology. That might mean the surface isn’t communicating with the underlying ocean,” said Britney Schmidt, lead author of the paper and postdoctoral fellow at the Institute for Geophysics, University of Texas at Austin. “Now, we see evidence that it’s a thick ice shell that can mix vigorously and new evidence for giant shallow lakes. That could make Europa and its ocean more habitable.”
Schmidt and her team focused on Galileo images of two roughly circular, bumpy features on Europa’s surface called chaos terrains. Based on similar processes seen on Earth — on ice shelves and under glaciers overlaying volcanoes — they developed a four-step model to explain how the features form. The model resolves several conflicting observations. Some seemed to suggest the ice shell is thick. Others suggest it is thin.
This recent analysis shows the chaos features on Europa’s surface may be formed by mechanisms that involve significant exchange between the icy shell and the underlying lake. This provides a mechanism or model for transferring nutrients and energy between the surface and the vast global ocean already inferred to exist below the thick ice shell. This is thought to increase the potential for life there.
The study authors have good reason to believe their model is correct, based on observations of Europa from Galileo and of Earth. Still, because the inferred lakes are several miles below the surface, the only true confirmation of their presence would come from a future spacecraft mission designed to probe the ice shell. Such a mission was rated as the second highest priority flagship mission by the National Research Council’s recent Planetary Science Decadal Survey and is being studied by NASA.
“This new understanding of processes on Europa would not have been possible without the foundation of the last 20 years of observations over Earth’s ice sheets and floating ice shelves,” said Don Blankenship, a co-author and senior research scientist at the Institute for Geophysics, where he leads airborne radar studies of the planet’s ice sheets.
Galileo was the first spacecraft to directly measure Jupiter’s atmosphere with a probe and conduct long-term observations of the Jovian system. The probe was the first to fly by an asteroid and discover the moon of an asteroid. NASA extended the mission three times to take advantage of Galileo’s unique science capabilities, and it was put on a collision course into Jupiter’s atmosphere in September 2003 to eliminate any chance of impacting Europa.
The Galileo mission was managed by NASA’s Jet Propulsion Laboratory in Pasadena, Calif., for the agency’s Science Mission Directorate.