Although there is no evidence that microorganisms ever existed on Ceres, the results of a new study support theories that this dwarf planet may have once had conditions suitable to support single-celled lifeforms.
This illustration depicts the interior of Ceres, including the transfer of water and gases from the rocky core to a reservoir of salty water; carbon dioxide and methane are among the molecules carrying chemical energy beneath Ceres’ surface. Image credit: NASA / JPL-Caltech.
Science data from NASA’s Dawn mission previously showed that the bright, reflective regions on Ceres’ surface are mostly made of salts left over from liquid that percolated up from underground.
Later analysis in 2020 found that the source of this liquid was an enormous reservoir of brine, or salty water, below the surface.
In other research, the Dawn mission also revealed evidence that Ceres has organic material in the form of carbon molecules — essential, though not sufficient on its own, to support microbial cells.
The presence of water and carbon molecules are two critical pieces of the habitability puzzle on the dwarf planet.
The new findings offer the third: a long-lasting source of chemical energy in Ceres’ ancient past that could have made it possible for microorganisms to survive.
This result does not mean that Ceres had life, but rather, that there likely was ‘food’ available should life have ever arisen on Ceres.
In a new study, lead author Dr. Sam Courville from Arizona State University and NASA’s Jet Propulsion Laboratory built thermal and chemical models mimicking the temperature and composition of Ceres’ interior over time.
They found that 2.5 billion years or so ago, Ceres’ subsurface ocean may have had a steady supply of hot water containing dissolved gases traveling up from metamorphosed rocks in the rocky core.
The heat came from the decay of radioactive elements within the dwarf planet’s rocky interior that occurred when Ceres was young — an internal process thought to be common in our Solar System.
“On Earth, when hot water from deep underground mixes with the ocean, the result is often a buffet for microbes — a feast of chemical energy,” Dr. Courville said.
“So it could have big implications if we could determine whether Ceres’ ocean had an influx of hydrothermal fluid in the past.”
The Ceres we know today is unlikely to be habitable. It is cooler, with more ice and less water than in the past.
There is currently insufficient heat from radioactive decay within Ceres to keep the water from freezing, and what liquid remains has become a concentrated brine.
The period when Ceres would most likely have been habitable was between a half-billion and 2 billion years after it formed (or about 2.5 billion to 4 billion years ago), when its rocky core reached its peak temperature.
That’s when warm fluids would have been introduced into Ceres’ underground water.
The dwarf planet also doesn’t have the benefit of present-day internal heating generated by the push and pull of orbiting a large planet, like Saturn’s moon Enceladus and Jupiter’s moon Europa do.
So Ceres’ greatest potential for habitability-fueling energy was in the past.
“Since then, Ceres’ ocean has likely become a cold, concentrated brine with fewer sources of energy, making it less likely to be habitable at present,” the authors concluded.
A paper on the findings was published today in the journal Science Advances.
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Samuel W. Courville et al. 2025. Core metamorphism controls the dynamic habitability of mid-sized ocean worlds – The case of Ceres. Science Advances 11 (34); doi: 10.1126/sciadv.adt3283