Dwarf planet Ceres in Mars-Jupiter asteroid belt could be hiding saltwater reservoir below surface: NASA study

The discovery was made possible by Dawn spacecraft which scanned the planet by flying 35 kilometers above the surface


                            Dwarf planet Ceres in Mars-Jupiter asteroid belt could be hiding saltwater reservoir below surface: NASA study
(Anton Ermakov, UC Berkeley, NASA/JPL)

In its final moments, NASA's spacecraft Dawn uncovered a secret that Ceres, a dwarf planet in our solar system, has been hiding for ages. Buried beneath the surface could be salty water bodies, the space agency has revealed. The discovery opens doors to investigating the possibility of life beyond Earth. Ceres is located in the asteroid belt between Mars and Jupiter. It was once an ocean world that likely froze over the years. Telescopes pointed to the dwarf planet from Earth indicated bright regions. NASA's Dawn spacecraft was tasked with figuring out the mysteries behind the shiny surface.

Previously, data suggested liquid seeping into the surface — but there were many unanswered questions. Towards the end of its mission, Dawn scanned the dwarf planet by flying 35 kilometers above the surface. It had its eyes set on Occator Crater, a 20-million-year-old impact crater.  The spacecraft also studied two regions within the crater: Cerealia Facula and the Vinalia Faculae. Analyzing the data, scientists noted that that liquid came from a deep reservoir of brine, or salt-enriched water.

"Dawn accomplished far more than we hoped when it embarked on its extraordinary extraterrestrial expedition," said Mission Director Marc Rayman of NASA's Jet Propulsion Laboratory in Southern California. "These exciting new discoveries from the end of its long and productive mission are a wonderful tribute to this remarkable interplanetary explorer," he added.

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)

The impact — from asteroids or meteors -- created the Occator Crater, possibly leaving behind cracks. Though these cracks, the brine reached the surface. And as the water evaporated, it left behind salt crust, which then created these bright patches. How is the saltwater reaching the surface? According to Dawn Principal Investigator Carol Raymond, the heat of the impact melted a slushy area just beneath the surface of Cerealia Facula. "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 the brine to continue percolating to the surface," she said in a statement.

What is more, water on the surface of Ceres should dry up within 100 years, But Dawn detected water during its mission. This suggests the fluids must have reached the surface very recently, NASA said. Further, the brine may be seeping into the surface to this day. Driving the theory is the discovery of salt compounds — sodium chloride chemically bound with water and ammonium chloride — concentrated in Cerealia Facula. Researches also found another clue that supports the existence of liquid water. The dwarf planet is home to odd conical hills or small ice mountains created by frozen pressurized groundwater. Such features have been spotted on Mars as well but never on a dwarf planet, NASA said.

“This paper provides the first coherent story for the connection between the surface evaporates and the deep brine for the region of Occator and leaves the question about whether the brine layer is global open to future investigation,” said Anton Ermakov, a University of California, Berkeley, postdoctoral fellow who works with the Dawn team.

The findings are presented in a special collection of papers. Here is the link.

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