The plumes of Enceladus erupt with water — as well as clues to what lies beneath this icy moon of Saturn
Enceladus is an active moon, erupting with geysers of water ice, sending vast quantities of frozen material into the cold, dark space surrounding Saturn. This body, the sixth-largest moon of Saturn, is also a water world, where vast bodies of liquid water run beneath its frozen surface.
A new geochemical model of Enceladus shows carbon dioxide seen rising form these mighty geysers is likely the product of chemical reactions which occur on the ocean floor of this Saturnian satellite. This suggests a geological and chemical environment far more complex than previously believed, researchers suggest.
“By understanding the composition of the plume, we can learn about what the ocean is like, how it got to be this way and whether it provides environments where life as we know it could survive. We came up with a new technique for analyzing the plume composition to estimate the concentration of dissolved CO2 in the ocean. This enabled modeling to probe deeper interior processes,” explained Christopher Glein of Southwest Research Institute (SwRI).
A Chilly Exterior, but a Warm Heart
“…the geysers flooding from deep in its vault: in my mouth I felt the taste of fire again, of blood and carnations, of rock and scald.”
— Pablo Neruda
Enceladus, discovered by astronomer William Herschel in 1789, was not visited by spacecraft until the passage of Voyager 1 and 2 in the opening years of the 1980’s. This pair of flybys showed the moon was the brightest body in the solar system, reflecting almost all the light which falls on its surface.
In February 2005, the Cassini Spacecraft carried out its first close encounter with Enceladus. For 13 years, the spacecraft explored Saturn, returning a wealth of data on that mighty world, together with its attendant moons and mighty ring system. On October 28, 2015, the spacecraft passed through one of the plumes, as a geyser erupted beneath.
Analysis of data from this historic encounter suggests the carbon dioxide released from geysers on Enceladus was likely the result of reactions between the rocky core of the moon and water in its oceans. Combined with recent discoveries of hydrogen gas and silica from the ocean, this discovery points to an active, diverse ocean environment on that distant moon.
“Based on our findings, Enceladus appears to demonstrate a massive carbon sequestration experiment… [W]e derived CO2 concentration ranges that are intriguingly similar to what would be expected from the dissolution and formation of certain mixtures of silicon- and carbon-bearing minerals at the seafloor,” Glein stated.
The data reveals the core of Enceladus is likely composed of carbon-rich material near its surface, like limestone on Earth. Closer to the center, deposits rich in magnesium and iron are being transformed into the mineral serpentine.Oxidation of iron from ocean water releases hydrogen, while fluids rich in silica arise from reactions with quartz-bearing carbonated rocks.
On Earth, hydrothermal vents drive complex chemical reactions, which may have played a significant role in sparking life on our home world. This new finding suggests a similar diverse chemical playground could exist beneath the frozen crust of Enceladus.
Water is essential to all life on Earth (even if tardigrades can survive decades without it), making Enceladus one of the most likely places in the solar system to find alien life.
A mission to explore the oceans of Enceladus would be well worth a trip, if only to reveal the secrets of its eternally-hidden oceans.
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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