New discovery from a team including Carnegie Mellon University’s Christopher Glein has disclosed pH of water spewing from a geyser-like plume on Saturn’s moon Enceladus that could support towards determining whether life could exist, or could have previously existed, on Saturn’s moon Enceledus.
Enceladus is thought to have a liquid water ocean beneath its icy surface. The hidden ocean is believed as the source of the plume of water vapor and ice that the Cassini spacecraft has observed venting from the moon’s south polar region.
To regulate the pH of Enceladus’ ocean, the team came up with a new chemical model based on mass spectrometry data of ice grains and gases in Enceladus’ plume gathered by Cassini.
The pH imparts us how acidic or basic the water is. It is the eventual determinant for understanding geochemical processes inside the moon that are considered vital in determining Enceladus’ potential for acquiring and hosting life.
The model shows that the plume, and by inference the ocean, is salty with an alkaline pH of about 11 or 12, which is similar to that of glass-cleaning solutions of ammonia.
\It has the same sodium chloride (NaCl) salt as our oceans here on Earth. Its additional substantial sodium carbonate (Na2CO3) makes the ocean more similar to our planet’s soda lakes such as Mono Lake in California.
The ocean’s high pH is interpreted to be a key consequence of serpentinization caused by a metamorphic, underwater geochemical process.
On Earth, serpentinization when takes place in a certain kinds of so-called “ultrabasic” or “ultramafic” rocks (low in silica and high in magnesium and iron) are brought up to the ocean floor from the upper mantle and chemically interact with the surrounding water molecules.
While on Enceladus, serpentinization would take place when ocean water circulates through a rocky core at the bottom of its ocean.
“Why is serpentinization of such great interest? Because the reaction between the metallic rocks and the ocean water also produces molecular hydrogen (H2), which provides a source of chemical energy that is essential for supporting a deep biosphere in the absence of sunlight inside moons and planets,” Glein said.
“This process is central to the emerging science of astrobiology, because molecular hydrogen can both drive the formation of organic compounds like amino acids that may lead to the origin of life, and serve as food for microbial life such as methane-producing organisms.
“As such, serpentinization provides a link between geological processes and biological processes. The discovery of serpentinization makes Enceladus an even more promising candidate for a separate genesis of life,” said Glein.