Dwarf planet Ceres turns out to be an ocean world

Tiny dwarf planet Ceres sits between Mars and Jupiter in the asteroid belt, and this small body turns out to be full of surprises. A new analysis of data collected by NASA’s Dawn mission, which went silent in 2018, suggests that the planet could be an ocean world, despite being far from the sun.

Dawn previously observed white spots on Ceres’s surface which are believed to be evidence of ancient ice volcanoes erupting and spewing cryomagma onto the surface. Now, further data from the mission has been analyzed to show that these patches of sodium carbonate came from a reservoir of briny water beneath the planet’s surface.

A mosaic image using false color
This mosaic image uses false color to highlight the recently exposed brine, or salty liquids, that were pushed up from a deep reservoir under Ceres’ crust. In this view of a region of Occator Crater, they appear reddish. NASA/JPL-Caltech/UCLA/MPS/DLR/IDA

This is especially interesting because Ceres receives little heat from the sun and, unlike other larger planets, is not heated by significant gravitational interactions either. But now scientists know that there is water on the dwarf planet.

“For the large deposit at Cerealia Facula, the bulk of the salts were supplied from a slushy area just beneath the surface that was melted by the heat of the impact that formed the crater about 20 million years ago,” Dawn principal investigator Carol Raymond explained in a statement. “The impact heat subsided after a few million years; however, the impact also created large fractures that could reach the deep, long-lived reservoir, allowing brine to continue percolating to the surface.”

mosaic of Ceres' Occator Crater
This mosaic of Ceres’ Occator Crater is composed of images NASA’s Dawn mission captured on its second extended mission, in 2018. Bright pits and mounds (foreground) were formed by salty liquid released as Occator’s water-rich floor froze after the crater-forming impact about 20 million years ago. NASA/JPL-Caltech/UCLA/MPS/DLR/IDA/USRA/LPI

The fact Dawn is still producing new findings about this body two years after finishing its mission goes to show how much can be learned from these ambitious projects.

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

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