MAR 12, 2015 11:59 AM PDT

Ocean Discovered on Jupiter's Moon

An ocean beneath the frozen surface of Ganymede was discovered by the Hubble Space Telescope
The biggest moon in the solar system harbors a salty ocean beneath its frozen surface, according to a study that examined the moon's flickering auroras to probe its interior.

A number of worlds in our solar system are thought to have oceans. But this is the first clear-cut data of its kind to suggest that a sea lies hidden under the icy shell of Jupiter's moon Ganymede, which is 50% bigger than our own moon. Scientific models predicted an ocean on Ganymede, and when NASA's Galileo spacecraft visited Ganymede in the 1990s, it collected data that hinted at an ocean. But new images from the Hubble Space Telescope offer strong confirmation of a liquid body of water inside Ganymede, scientists say.

Galileo's observations "provide inconclusive evidence for the ocean," says study co-author Joachim Saur of the University of Cologne. "The Hubble data require an ocean."

Finding an ocean on a celestial body hundreds of millions of miles from Earth is no easy feat. Saur and his team turned to the space-going Hubble, which trained its keen eyes on Ganymede in 2010 and again in 2011. The Hubble focused on Ganymede's two auroras, shimmering patterns in the sky similar to the earthly phenomenon known as the Northern Lights. A person standing on Ganymede's surface and looking up would see a red glow, Saur says.

Ganymede has two auroras, one around its north pole and one around its south pole, both created in part by the moon's own magnetic field. These auroras don't stay fixed in place. Instead, they wander slightly across Ganymede's face. With the help of supercomputers, the scientists calculated how much Ganymede's auroras would shift if the moon had a salty sea. A layer of salty water could carry electrical current, generating another magnetic field that would affect the auroras.

The researchers found that the aurora shift witnessed by Hubble nicely matched the prediction of what should happen if Ganymede has an ocean. Just as importantly, the Hubble data did not match the prediction for an ocean-less Ganymede, the scientists reported online last month in the Journal of Geophysical Research.

Ganymede's ocean is sandwiched between two layers of ice. That's not particularly hospitable to life, says planetary scientist William McKinnon of Washington University in St. Louis, who didn't work on the new study. But Saur says it's still possible that Ganymede's waters are habitable.

Other scientists praise the study for revealing important new evidence about Ganymede's hidden interior.

Previous evidence of an ocean on the gigantic moon was "somewhat ambiguous," University of California-Santa Cruz planetary scientist Francis Nimmo, who was not part of the study, says via e-mail. "So this study is ... nice in that it provides independent confirmation of a subsurface ocean on Ganymede."

The new findings are "very significant," McKinnon agrees, though he thinks they're not "air-tight. ... What we need to do is go back to Ganymede and take measurements on site."

Fortunately for Ganymede partisans, the European Space Agency is planning to launch a spacecraft in 2022 to explore this supermoon and its neighbors. Saur says he welcomes the mission as a chance to confirm his study's findings, which he calls "solid science" but based on an "indirect method."

A solar-system sea is "really only 100% certain," he says, when "you have a finger in the water."

Source: USA Today
About the Author
  • I'm a writer living in the Boston area. My interests include cancer research, cardiology and neuroscience. I want to be part of using the Internet and social media to educate professionals and patients in a collaborative environment.
You May Also Like
JUN 19, 2018
Space & Astronomy
JUN 19, 2018
Watch the Heart of the ESA's ExoMars Rover Endure Stress Testing
The European Space Agency plans to send its ExoMars rover to Mars in 2020 to explore the red planet’s surface for signs of past (or present) life. Bu...
JUL 03, 2018
Space & Astronomy
JUL 03, 2018
Astronomers Capture the Formation of a Young Exoplanet
The mechanisms responsible for planetary formation have captivated astronomers for as long as we can remember, but a newly-captured image of a distant star...
JUL 15, 2018
Space & Astronomy
JUL 15, 2018
Did Juno Just Spot a New Active Volcano on Io's Surface?
NASA’s Juno probe began orbiting Jupiter a little more than two years ago, and it has already returned heaps of valuable data that scientists are now...
AUG 06, 2018
Space & Astronomy
AUG 06, 2018
NASA's TESS Spacecraft Spies a Comet
NASA’s Transiting Exoplanet Survey Satellite (TESS) officially began scientific operations at the end of last month, a move that will help the space...
AUG 26, 2018
Space & Astronomy
AUG 26, 2018
NASA's OSIRIS-REx Spacecraft Snaps its First Picture of Bennu
NASA’s Origins, Spectral Interpretation, Resource Identification, Security-Regolith Explorer (OSIRIS-REx) mission is now one step closer to realizing...
AUG 27, 2018
Space & Astronomy
AUG 27, 2018
NASA's Spitzer Space Telescope Celebrates 15 Years in Space
NASA engineers originally designed the Spitzer Space Telescope to observe the heavens for approximately 2.5 years. But 15 years later, the space observator...
Loading Comments...