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What’s inside Ceres? Dawn mission finds possible ancient ocean remnants

Dawn spacecraft

Does the dwarf planet Ceres contain a subsurface ocean? Recent data from NASA’s Dawn spacecraft suggests it may. Image Credit: NASA / JPL

Orbiting since March of 2015, NASA’s Dawn spacecraft continues to provide exciting science from Ceres – a dwarf planet and the largest object in the asteroid belt between Mars and Jupiter. Two studies, part of the Dawn mission’s second extension, are using new data to shed light on a possible liquid past.

“More and more, we are learning that Ceres is a complex, dynamic world that may have hosted a lot of liquid water in the past, and may still have some underground,” said Julie Castillo-Rogez, Dawn project scientist and co-author of the studies, based at NASA’s Jet Propulsion Laboratory, Pasadena, California.

This prompts the questions of what became of that ocean – and could Ceres still have liquid today?

Anomalies in Dawn’s Orbit Reveal Geological Activity

The first of the two studies, led by Anton Ermakov, observed small changes in Dawn’s orbital motion utilizing NASA’s Deep Space Network. These discrepancies between the scientists’ models of Ceres’ gravity and what Dawn observed in specific locations can be associated with subsurface structures. His team is using gravity to peer under the dwarf planet’s surface.

“Ceres has an abundance of gravity anomalies associated with outstanding geologic features,” Ermakov said. His research supports the possibility that Ceres is geologically active – if not now, then it might have been in the recent past. His team is now using this data to gain a better understanding of the origin of these features, which are thought to be different expressions of cryovolcanism – a potential eruption of water and other volatiles onto the surface due to internal heating.

Ceres as seen by NASA's Dawn spacecraft

This animation shows the dwarf planet Ceres as seen by NASA’s Dawn. The map overlaid at right gives scientists hints about Ceres’ internal structure from gravity measurements. Animation & Caption Credit: NASA / JPL-Caltech / UCLA / MPS / DLR / IDA

Data Allows Modeling of Ceres’ Topology

The second study, led by Roger Fu at Harvard University in Cambridge, Massachusetts, used Dawn mission data to investigate the strength and composition of Ceres’ crust and deeper interior. By modeling how Ceres’ crust flows, Fu and his colleagues believe that Ceres once had more pronounced surface features, but they have smoothed out over time. This type of flattening requires a high-strength crust resting on a more deformable layer, which the researchers interpret as meaning it contains some liquid. A strong, rock-dominated crust can remain unchanged over the 4.5-billion-year-old age of the Solar System, whereas a weak crust, rich in ices and salts, would deform over that time.

Putting the Pieces Together

The researchers surmise that most of Ceres’ ancient ocean is now frozen and bound up in the crust, remaining in the form of ice, clathrate hydrates, and salts. However, it’s possible there is residual liquid underneath and that, at least, some of the ocean is not entirely frozen.

“This continues to be a mission for everyone who yearns for new knowledge, everyone who is curious about the cosmos, and everyone who is exhilarated by bold adventures into the unknown,” said Marc Rayman, mission director and chief engineer, based at JPL via a release issued by the agency. The Dawn mission continues to deliver new knowledge about these small but intricate worlds, which hold clues to the formation of planets in the Solar System.

Leaving Earth

The Dawn spacecraft took flight on Sept. 27, 2007, at 7:34 a.m. EDT (11:34 GMT) from Cape Canaveral Air Force Station’s Space Launch Complex 17B located in Florida. The spacecraft was sent aloft atop United Launch Alliance’s Delta II 7925H rocket with the spacecraft itself being produced by Orbital Sciences Corp., NASA’s Jet Propulsion Laboratory, and UCLA.

Video courtesy of NASA / JPL



Ryan Chylinski is a multi-disciplinary photographer, entrepreneur, and space science enthusiast from the flagship city of Erie, Pennsylvania. Chylinski received his BS from The Rochester Institute of Technology in, where he studied computer engineering at the College of Applied Science and Technology in Rochester, New York. Commemorating the 40th anniversary of the Voyager 1 and 2 spacecraft. Chylinski is now travelling full-time with the open-source photographic apprenticeship: and - inside a different kind of ship of the imagination. His work, and ongoing studies remain closely entwined: Chylinski’s out to ignite the cosmic perspective in artists and entrepreneurs and to inspire a personal exploration of the hidden universe in a very practical way.

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