Ice on Ceres' surface originated from water that percolated up from internal reservoirs of liquid brine. Salt deposits indicate the brine contained carbon, an essential element for life. Radioactive decay in Ceres' core produced chemical energy and heat strong enough to warm an internal ocean. Warmth combined with water and carbon could have supported chemotrophic microbes reliant on chemical energy rather than sunlight. Surface conditions remained extremely cold and irradiated, confining habitability to subsurface environments. Any habitable period likely occurred roughly 0.5–2 billion years after formation, making detection of ancient life extremely difficult today.
Dwarf planet Ceres, the unpleasant lump of icy rock orbiting between Mars and Jupiter, once had an environment in which microbes might have thrived. So says a paper titled "Core metamorphism controls the dynamic habitability of mid-sized ocean worlds-The case of Ceres" published this week in the journal Science Advances. As distilled by NASA, whose Dawn spacecraft captured the data used in the paper, previous examinations of Ceres suggested that ice present on its surface came from water that percolated up from internal reservoirs of liquid brine. Salt deposits on Ceres' surface suggest that brine contained carbon, which microbes need.
The new paper suggests the dwarf planet may also have produced enough chemical energy - thanks to radioactive decay of material in its core - to make its internal ocean warm. Maybe warm enough that, in concert with the presence of water and carbon, microbes would have felt at home. Any microbes that lived on Ceres would have been "chemotrophs" - organisms that rely on chemical energy rather than solar energy, because even when the dwarf planet was warm inside, its surface was hellishly cold and exposed to radiation.
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