Researchers from the “Planetary Sciences and Remote Sensing” group at Freie Universität Berlin have recently published a study in Science Advances, led by Professor Frank Postberg. The study presents new evidence that the composition of the ocean hidden beneath Enceladus’s icy surface may be easier to determine than previously thought. In a second publication, conducted together with Dr. Nozair Khawaja, the researchers show that certain microorganisms could tolerate the conditions in Enceladus’s ocean better than previously thought. Together, these findings improve our understanding of how potential signs of life could be detected on Saturn’s moon.

Enceladus is one of the most promising places to search for extraterrestrial life because it has a subsurface ocean containing salts and organic compounds. NASA’s Cassini spacecraft detected these materials by flying through plumes from Enceladus’s south polar region, which eject ice particles hundreds of kilometers into space.

Postberg’s new publication, “Cassini CDA Observes Compositional Segregation of Enceladus’ Ice Grains from Slow Freezing and Fragmentation of Oceanic Spray,” shows that ocean droplets can freeze more slowly as they are moving through cracks in Enceladus’ ice shell than previously assumed. As the droplets freeze more slowly, salts and organic compounds become distributed in different regions within the droplets. When the droplets are accelerated through the cracks and into space, they can fragment, separating these components into different ice grains. As a result, some ice particles may consist predominantly of a single, highly concentrated substance that was previously segregated within the droplet. This could make it easier for future spacecraft to detect biosignatures.

The second study, led by Ludwig-Maximilians-Universität München (LMU) and involving Postberg and Khawaja, “Enceladus-Like Geochemistry Fuels Methanogenesis under Extreme CO₂-Limitation,” showed that a methane-producing microorganism could survive and produce methane under simulated Enceladus conditions.

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Publications

• Frank Postberg et al.: “Cassini CDA Observes Compositional Segregation of Enceladus’ Ice Grains from Slow Freezing and Fragmentation of Oceanic Spray.” Science Advances (2026): https://www.science.org/doi/10.1126/sciadv.aee7256

• Vanessa Helmbrecht, Frank Postberg, Nozair Khawaja et al.: “Enceladus-Like Geochemistry Fuels Methanogenesis under Extreme CO₂-Limitation.” Science Advances (2026): https://www.science.org/doi/10.1126/sciadv.aei0167

Contact

Prof. Dr. Frank Postberg, Head of Planetary Sciences and Remote Sensing, Institute of Geological Sciences, Department of Earth Sciences, Freie Universität Berlin, Email: frank.postberg@fu-berlin.de

Dr. Nozair Khawaja, Research Group Leader at the DLR Institute of Space Research and the Institute of Geological Science, Freie Universität Berlin, Email: nozair.khawaja@fu-berlin.de