Salty water discovered below surface on dwarf planet Ceres

Dwarf planet Ceres
NASA/Courtesy
NASA’s Dawn spacecraft was able to fly at the low altitude of 22 miles above Ceres, capturing high-resolution images and data.

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A recent analysis shows that Ceres, the only dwarf planet in the inner solar system, has reservoirs of salty water beneath its surface.

A team of researchers from NASA’s Dawn discovery mission used data and images from the Dawn spacecraft to discover that subsurface bodies of brine exist beneath the heavily cratered exterior of the dwarf planet.

NASA’s Dawn spacecraft was able to fly at the low altitude of 22 miles above Ceres, capturing high-resolution images and data, said Anton Ermakov, a UC Berkeley postdoctoral fellow on the research team. According to a study published by the team, analysis of the information gathered showed bright spots of sodium deposits on the surface of a crater.

“We think that the surface bright deposits are sourced from a preexisting subsurface brine reservoir,” said Ermakov. “The impact created fractures which provided pathways for the salty water to reach the surface to form the bright deposits on the surface.”

According to Ermakov, analysis of the data showed a large gap in time between when the crater was made and when the bright spots appeared.

The research team’s theory, Ermakov said, is that when an impact formed the crater, it also fractured parts of the surface. These fractures allowed underground liquid to rise to the surface and evaporate, leaving salt deposits.

These subsurface reservoirs would also explain the gravitational anomalies found in the data, according to Ermakov.

“We know the crater is young and the bright deposits on the surface are even younger. The information can’t be explained just by the impact heat,” Ermakov said. “The modeling showed that the impact can fracture the surface, relatively far from the impact location itself.”

According to Ermakov, who has been analyzing the gravitational data from NASA’s Dawn spacecraft since 2015, the different models of the data they used took months to run, making the discovery a prolonged process rather than an instantaneous or surprising one.

The next steps for studying Ceres include using the geophysical data from the Dawn mission to gain a better understanding of the distribution of subsurface water on Ceres and determine whether it is regional or global, Ermakov said.

“Dawn accomplished far more than we hoped when it embarked on its extraordinary extraterrestrial expedition,” said Marc Rayman, mission director of NASA’s Jet Propulsion Laboratory, in a press release. “These exciting new discoveries from the end of its long and productive mission are a wonderful tribute to this remarkable interplanetary explorer.”

Contact Gigi Nibbelink at [email protected] and follow her on Twitter at @giginibbelink.