The dwarf planet is cold now, but new research paints a picture of Ceres hosting a deep, long-lived energy source that may have maintained habitable conditions in the past.<\/p>\n
New NASA research has found that Ceres may have had a lasting source of chemical energy: the right types of molecules needed to fuel some microbial metabolisms. Although there is no evidence that microorganisms ever existed on Ceres, the finding supports theories that this intriguing dwarf planet, which is the largest body in the main asteroid belt between Mars and Jupiter, may have once had conditions suitable to support single-celled lifeforms.<\/p>\n
Science data from NASA\u2019s Dawn mission<\/a>, which ended in 2018, previously showed that the bright, reflective regions on Ceres\u2019 surface are mostly made of salts left over from liquid that percolated up from underground. Later analysis<\/a> 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<\/a> in the form of carbon molecules \u2014 essential, though not sufficient on its own, to support microbial cells.<\/p>\n The presence of water and carbon molecules are two critical pieces of the habitability puzzle on Ceres. The new findings offer the third: a long-lasting source of chemical energy in Ceres\u2019 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 \u201cfood\u201d available should life have ever arisen on Ceres.<\/p>\n In the study, published<\/a> in Science Advances on Aug. 20, the authors built thermal and chemical models mimicking the temperature and composition of Ceres\u2019 interior over time. They found that 2.5 billion years or so ago, Ceres\u2019 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\u2019s rocky interior that occurred when Ceres was young \u2014 an internal process thought to be common in our solar system.<\/p>\n \u201cOn Earth, when hot water from deep underground mixes with the ocean, the result is often a buffet for microbes \u2014 a feast of chemical energy. So it could have big implications if we could determine whether Ceres\u2019 ocean had an influx of hydrothermal fluid in the past,\u201d said Sam Courville, lead author of the study. Now based at Arizona State University in Tempe, he led the research while working as an intern at NASA\u2019s Jet Propulsion Laboratory in Southern California, which also managed the Dawn mission.<\/p>\n 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.<\/p>\n 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\u2019s when warm fluids would have been introduced into Ceres\u2019 underground water.<\/p>\n The dwarf planet also doesn\u2019t have the benefit of present-day internal heating generated by the push and pull of orbiting a large planet, like Saturn\u2019s moon Enceladus and Jupiter\u2019s moon Europa do. So Ceres\u2019 greatest potential for habitability-fueling energy was in the past.<\/p>\n This result has implications for water-rich objects throughout the outer solar system, too. Many of the other icy moons and dwarf planets that are of similar size to Ceres (about 585 miles, or 940 kilometers, in diameter) and don\u2019t have significant internal heating from the gravitational pull of planets could have also had a period of habitability in their past.<\/p>\n A division of Caltech in Pasadena, JPL managed Dawn\u2019s mission for NASA\u2019s Science Mission Directorate in Washington. Dawn was a project of the directorate\u2019s Discovery Program, managed by NASA\u2019s Marshall Space Flight Center in Huntsville, Alabama. JPL was responsible for overall Dawn mission science. Northrop Grumman in Dulles, Virginia, designed and built the spacecraft. The German Aerospace Center, Max Planck Institute for Solar System Research, Italian Space Agency and Italian National Astrophysical Institute were international partners on the mission team.<\/p>\n For a complete list of mission participants, visit:<\/p>\n https:\/\/solarsystem.nasa.gov\/missions\/dawn\/overview\/<\/a><\/p>\n