Could there be life on Saturn’s moon Enceladus? This icy world may be small (1/7 the size of our moon), but it has a global ocean of water beneath its outer ice crust.
In fact, NASA’s Cassini spacecraft analyzed some of that water by flying through and sampling the moon’s water-vapor plumes. Those plumes originate from the ocean below and erupt onto the surface into space.
The analysis results suggested that the ocean might well be suitable for some kind of life, at least microbes. Last month, NASA announced a new study from researchers at the University of Washington that further supports this possibility.
It shows that the ocean is moderately alkaline (not too acidic) and may be even more habitable than previously thought.
Thanks to Cassini, scientists already know that the ocean is fairly salty, like oceans on our planet. There is even evidence for hydrothermal vents on the ocean floor of Enceladus. On Earth, such vents provide heat and nutrients for a wide variety of organisms.
Enceladus harbors an ocean beneath its ice crust that erupts spectacular plumes from fissures at the south pole. The plume composition was measured by the Cassini spacecraft, and provides evidence for the ocean’s gas content, salinity, pH, and potential for life.
When Cassini analyzed the water-vapor plume spray, it found that the plumes contain water vapor, ice crystals, salts, ammonia, methane and various organic molecules. This isn’t proof of life yet, but it is tantalizing.
Oceans on Earth currently have an average pH of 8.1. Seven is considered to be a neutral pH. Anything below that is acidic and anything above that is basic (alkaline).
If Enceladus’ ocean isn’t too acidic (moderately alkaline), that’s a good sign for possible life being able to exist. Earlier this year, researchers at the Massachusetts Institute of Technology (MIT) also reported that the ocean isn’t too salty, either.
The ocean is salty, like Earth’s oceans, but too much salt can be a bad thing for living organisms. Another study from a team of biologists in 2021 showed that Enceladus’ ocean also contains a lot of methane.
Scientists don’t know yet, of course, if the methane is biological in origin or not, but it is certainly a possibility.
The new ocean model discussed here, showing that there is enough carbon dioxide and hydrogen in the ocean to support hydrogenotrophic methanogens, could be a clue, perhaps?
Yet another study announced in 2020 indicated that the inner complexity of Enceladus is good for life. An even earlier study from 2019 showed that Enceladus’ ocean is also the ideal age – one billion years old – to support life. Very intriguing!
The proposed Enceladus Orbilander mission for late next decade would search for life on Saturn’s icy moon.
Sci-nature.com / ABC Flash Point News 2022.