Source : Perth Now news
Saturn’s icy moon Enceladus could provide a home for alien life, after scientists found an ancient type of Earth microorganism can survive and produce methane under laboratory conditions designed to mimic its hidden ocean.
The discovery provides fresh evidence Enceladus, which orbits Saturn and conceals a global saltwater ocean beneath its frozen crust, has conditions potentially capable of sustaining microbial life.
The findings were published in Science Advances alongside separate research suggesting material blasted from the moon’s ocean into space may naturally separate into chemically distinct ice grains – potentially making signs of life easier for future spacecraft to detect.
Vanessa Helmbrecht, lead author of the first study at Ludwig Maximilian University of Munich, said: “Enceladus is considered to be one of the most promising places to search for extraterrestrial life.”
She added: “Our experiments show that its unique geochemistry could create conditions that are even more favourable for microbial life than we had previously thought.”
Enceladus has fascinated astrobiologists since the NASA, European Space Agency and Italian Space Agency Cassini-Huygens mission revealed jets erupting from fractures near its south pole were throwing material from its subsurface ocean hundreds of kilometres into space.
The moon appears inhospitable from the outside, with an intensely cold, ice-covered surface.
Beneath that shell, however, lies an ocean in contact with a rocky seafloor, while evidence points towards hydrothermal activity capable of providing chemical energy.
ESA says Enceladus possesses the principal ingredients associated with a potentially habitable environment – liquid water, an energy source and the necessary chemical elements.
Vanessa and her colleagues attempted to reproduce aspects of that environment in the laboratory and tested whether methane-producing archaea could function under the extreme conditions thought to occur there.
The study, Enceladus-like geochemistry fuels methanogenesis under extreme CO₂ limitation, found a methane-producing microorganism could survive and continue producing methane under simulated Enceladus conditions, including extremely restricted carbon dioxide availability.
The result does not show life exists on Enceladus.
Instead, it demonstrates an organism found on Earth can remain metabolically active under a laboratory reconstruction of some of the conditions scientists believe exist beneath the moon’s ice.
The finding comes alongside another major Enceladus study published in the same issue of Science Advances, led by Frank Postberg of Freie Universität Berlin.
Frank and his colleagues reanalysed about 1,000 mass spectra of salt-rich ice grains detected by Cassini’s Cosmic Dust Analyzer.
They found at least five main compositional types containing different concentrations of salts.
Laboratory experiments and calculations indicated large droplets of Enceladus ocean water could freeze slowly while travelling through the moon’s icy vents.
Different salts and organic compounds would separate within those droplets before collisions with the walls of the narrowing vents shattered them into much smaller grains.
That process could prove important to the search for extraterrestrial life because individual particles may contain highly concentrated substances that would otherwise be diluted in ocean water, potentially helping instruments aboard future spacecraft identify possible biosignatures.
The findings arrive as plans to return to Enceladus move forward.
ESA has identified the moon as the preferred destination for its first large-class Voyage 2050 mission and spent 2026 developing technologies for the proposed spacecraft.
Current ESA planning envisages a mission launching in the 2040s rather than a confirmed 2042 launch. The ambitious project could fly repeatedly through Enceladus’s plumes before deploying a lander near its south pole to collect and analyse material originating from the ocean below.
No spacecraft has previously landed on Enceladus.
The mission would build on the legacy of Cassini-Huygens, which spent 13 years exploring Saturn and its moons before deliberately plunging into Saturn’s atmosphere in 2017 – a manoeuvre designed partly to ensure potentially habitable worlds including Enceladus were not contaminated by microbes carried from Earth.
Frank’s team is already working on experiments intended to help future instruments recognise biological material inside Enceladus ice particles, including tests in which bacteria-coated particles are accelerated to cosmic velocities to determine what molecular signatures biological material leaves after high-speed impacts.
