The Tantalizing Mystery of the Solar System’s Hidden Oceans

And but, defiantly, these alien seas stay liquid.

A Mirror-Wrapped Ocean

Scientists suspect {that a} handful of moons orbiting Jupiter and Saturn—and perhaps even some spinning round Uranus and Neptune—harbor oceans. Hefty Ganymede and crater-scarred Callisto produce weak, Europa-like magnetic indicators. Saturn’s haze-covered Titan, too, very in all probability has a liquid-water subsurface ocean. These “are the five that most scientists in the community feel pretty confidently about,” stated Mike Sori, a planetary scientist at Purdue University.

So far, the solely absolute oceanic certainty is Enceladus. “That’s a no-brainer,” stated Carly Howett, a planetary scientist at the University of Oxford.

In the Eighties, some scientists suspected Enceladus had plumes; Saturn’s E ring was so clear and glossy that one thing—maybe from one of its moons—have to be leaking into area and always refreshing it. After Cassini lastly witnessed that planet-garnishing magic in motion, scientists briefly questioned whether or not the moon’s south-polar plumes could be the work of daylight vaporizing ice in the moon’s shell—a bit like dry ice boiling away when heated, maybe by daylight.

“For a while, there was this argument about whether there needed to be an ocean at all,” Nimmo stated. “What really nailed that was when [Cassini] flew through the plume and they found salt—sodium chloride. That’s an ocean.” There was nonetheless an opportunity that these plumes might be erupting from a smaller, extra remoted sea. But additional Cassini observations revealed that Enceladus’ shell is rocking forwards and backwards so acutely that it have to be separated from the moon’s deeper inside by a world ocean.

The plumes additionally pump out hydrogen and quartz, indicators of deep-sea hydrothermal vent exercise, stated Frank Postberg, a planetary scientist at the Free University of Berlin. On Earth, such vents produce the warmth and chemistry wanted to energy ecosystems that exist past the attain of daylight—communities of organisms that scientists as soon as thought couldn’t exist in our photosynthetically dependent world.

But what might be powering a vent system robust sufficient to warmth a whole ocean? Another moon—this one of the fiery selection—would offer these clues.

The Eternal, Infernal Tides

In June 1979, a month earlier than Voyager 2’s shut flyby of Europa, scientists introduced that Voyager 1 had glimpsed titanic, umbrella-shaped plumes billowing into area above Io—the eruptive fingerprints of a number of volcanoes.

This statement ought to have been baffling: Volcanism requires an inside warmth supply, and Io, like the different icy moons, ought to have been nothing greater than embers. But just a few months earlier, an unbiased workforce of scientists had accurately predicted that Io could be a hyperactive volcanic world.