Another heavenly body out there might be fostering life: Saturn’s moon Enceladus. Scientists have found that the pH of water coming from a geyser-like plume on Enceladus might be an indication of whether the moon can sustain life or not.
Enceladus, one of Saturn’s moons
The finding is considered to be pertinent to determine whether life might exist, or could have existed in the past, on the moon of Saturn. Enceladus is geologically active. Scientists believe it might have water in the liquid form underneath its icy surface – this hidden ocean might be the source of the plume of water vapour and ice that was observed by Cassini spacecraft in the past.
To determine the pH of Enceladus’ ocean, the researchers set up a new chemical model based on mass spectrometry data of ice grains and gases in Enceladus’ plume gathered by Cassini. The acidity or basicity of the water will help understand geochemical processes inside the moon. Finding more information pertaining to this will indicate whether the moon can sustain life or not.
According to the model, the plume, and thus the ocean, is salty of alkaline pH 11 to 12. The sodium chloride it contains as salt is the same as that in our oceans. Another of its compounds is sodium carbonate (Na2CO3) – this also bears resemblance to our planet’s soda lakes like the Mono Lake in the US.
The model also suggests that the high pH is caused by serpentinisation, which is a metamorphic, underwater geochemical process. Serpentinisation also happens on Earth when “ultrabasic” or “ultramafic” rocks come to the ocean floor from the upper mantle of the Earth to react chemically with the water molecules.
“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,” said one of the authors.
“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, serpentinisation provides a link between geological processes and biological processes. The discovery of serpentinisation makes Enceladus an even more promising candidate for a separate genesis of life,” said Glein.