The oceans of Enceladus could be more like the oceans of Earth than we believed — but is there life?
Orbiting around Saturn, the icy moon Enceladus makes an intriguing target for astronomers and planetary scientists. Like Jupiter’s moon Europa, Enceladus is one of the water worlds of our solar system where we may, one day, find primitive life.
First discovered by legendary astronomer William Herschel in 1789, Enceladus is about as wide across as the state of Arizona. In 2014, the Cassini spacecraft exploring the Saturnian system found evidence of a vast subsurface ocean encompassing this frozen moon. Covering the entire surface of this ocean is a layer of ice 20 kilometers (around 12.5 miles) thick.
Geysers erupting from the south pole of that world reveal an active geology at the alien seafloor. Frozen debris from these eruptions spew into space, trailing behind the moon as it orbits its planetary parent, forming the E ring encircling Saturn.
Watching water rush from the geysers of Enceladus provided astronomers an opportunity to study the chemistry of these hidden oceans.
A new study examining ocean currents on the sixth-largest moon of Saturn shows patterns in water flow could affect this world in much the same way they do on Earth.
Crunchy on the Outside, Watery Goodness Inside
“Before Cassini arrived at the Saturn system, planetary explorers only had hints that something interesting might be happening at Enceladus. Pictures from the Voyager spacecraft in the 1980s indicated that although this moon is small — only about 310 miles (500 kilometers) across — its icy surface is remarkably smooth in some places, and bright white all over. In fact, it’s the most reflective body in the solar system,” NASA reports.
This ocean underlying this ice dwarfs the waterways of Earth. While oceans on our home world cover 75% of the planet to an average depth of just 3.6 km (about 2.25 miles), the ocean on Enceladus covers the entire moon with a layer of water averaging 30 km (around 18.5 miles) deep.
Water, warmed by the core of Enceladus, rises, before it is cooled by the icy crust covering the mighty ocean.
The geysers of Enceladus, first seen by Cassini erupting from darker tiger stripes near the southern pole, offer astronomers an opportunity to glimpse the intriguing chemistry happening within these alien oceans.
“A handful of worlds are thought to have liquid water oceans beneath their frozen shell, but Enceladus sprays its ocean out into space where a spacecraft can sample it. From these samples, scientists have determined that Enceladus has most of the chemical ingredients needed for life, and likely has hydrothermal vents spewing out hot, mineral-rich water into its ocean,” NASA describes.
Working from a study of the shape of this icy crust, researchers at the California Institute of Technology (Caltech) studied how currents behave in the watery environs of Enceladus.
Building on data collected by the Cassini spacecraft, as well as studies of the icy waters of Antarctica, Caltech graduate student Ana Lobo and a team of researchers found water currents on Enceladus have similarities to conditions here on Earth.
An open-mouthed dive into the oceans of Earth quickly reveals the saltiness of terrestrial oceans. Salt is also found in the alien waters of Enceladus (although diving there is NOT recommended).
Observations from the Cassini spacecraft revealed ice on Enceladus was thinner at the polar regions, and thickest at the equator. This would suggest that melting takes place predominantly near the poles, while water freezes more easily in the equatorial regions of Enceladus.
When salty water freezes, salt is released, making surrounding water heavier than it would otherwise be, causing that water to sink. The opposite process takes place as ice melts back into liquid water.
“Knowing the distribution of ice allows us to place constraints on circulation patterns,” Lobo explains.
These processes could build massive flows within the oceans of Enceladus, forming a pole-to-equator circulation, the study concluded. These flows could influence the distribution of heat — as well as nutrients for any lifeforms living on this ocean world.
Enceladus is one of the most-intriguing worlds in our solar system for astrobiologists looking for a stage where alien life may have evolved. Other tempting targets include Saturn’s largest moon, Titan, awash in oceans of hydrocarbons, as well as another ice-encrusted water world, Europa, one of the four large moons of Jupiter.
Analysis of this new study was published in the journal Nature Geoscience.
James Maynard is the founder and publisher of The Cosmic Companion. He is a New England native turned desert rat in Tucson, where he lives with his lovely wife, Nicole, and Max the Cat.
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