Ceres, the dwarf planet closest to Earth, is an aquatic world and, according to new research, it may have a huge reservoir of salt water under its surface.
The reservoir on the small planet that orbits the Sun between Mars and Jupiter lies beneath a 20 million year old crater known as the Occator – and could house life.
The finding is based on an analysis of images from NASA's spacecraft Dawn, which was examined by a team from the California Institute of Technology on the surface of Ceres.
Dawn orbited Ceres, which was roughly 600 miles in diameter between 2015 and 2018 – roughly the vertical length of the UK – until he ran out of fuel.
In the past few months, it has only traveled 20 miles above the surface and focused on Occator Crater, where it performed imaging, scanning, and gravity analysis.
The finding is based on an analysis of images from NASA's Dawn spacecraft, which examined the surface of Ceres including “bright spots” in the crater
In the past few months, it has only traveled 20 miles above the surface and focused on Occator Crater, where it performed imaging, scanning, and gravity analysis
Dr. Carol Raymond, the mission's assistant principal investigator, said: "It suggests that Ceres is an ocean world and may have been geologically active in the recent past."
The observations are reported in seven articles published in Nature Astronomy, Nature Geoscience, and Nature Communications.
The team of Dr. Raymond believes the salt reservoir found beneath the dwarf planet's surface was fueled by the impact that caused the crater.
This led to the formation of salt deposits on the planet's surface, which from a distance appear as bright spots.
Raymond said, "The existence of a deep-seated brine reservoir below Occator is supported by recent gravity data."
Salt lowers the freezing point of water and makes it more likely to be liquid.
Another article described the detection of chloride salts – usually in sea ice – using instruments that mapped the crater using visible and infrared light.
It towers over the Cerealia Facula – a dome in the center of Occator Crater and it is the first time the compound has been found beyond Earth.
Lead author Maria Cristina De Sanctis of the National Institute of Astrophysics in Rome said this required liquid water combined with hydrothermal activity.
"The spatial distribution suggests that chloride salts are the solid residues of deep brine that have surfaced – or are still rising – over the past two million years," explained De Sanctis.
"These salts are very efficient at maintaining the warm internal temperature of Ceres and lowering the temperature of the brine. In this case, rising salty liquids can exist today."
At nearly 600 miles wide, Ceres is the largest object in the asteroid belt.
It's less than three times as far from the Sun as Earth – which is still close enough to feel the warmth, allowing the ice to melt and re-form.
Ceres was the first dwarf planet to be visited up close. It belongs to a specific class of objects – after the rocky inner planets like Earth and Mars and gas giants like Jupiter.
It has fascinated astronomers for decades as it is believed to be the record of the early solar system and its evolution.
Dr. Julie Castillo-Rogez, a planetary scientist at Caltech who was not involved in any of the studies, said Ceres had long been considered a primitive body.
NASA's spacecraft Dawn orbited Ceres, which was roughly 600 miles in diameter between 2015 and 2018 – roughly the vertical length of the UK – before it ran out of fuel
"Ceres is now a deep brine ocean world on a regional and potentially global scale," explained Castillo-Rogez.
"Further studies of the conditions of Ceres, and most importantly a follow-up mission, are needed to study the development and potential habitability of Ceres."
She said the results also had implications for life in icy worlds – like Jupiter's moons Europa and Ganymede.
NASA's Europa Clipper mission and Jupiter Icy Moons Explorer (JUICE) will be launched in the next decade.
Dr. Castillo-Rogez said, “The next decade of dwarf planet exploration requires that focus be placed on habitability in these developed oceans, which are likely to be rich in organic matter.
"Exposed natural salts in Occator allow for the direct procurement of the deep brine under the crater and are an obvious target for a future mission."
The various articles can be read by Nature.
DWARF PLANET CERES IS 590 MILES ABOVE AND WAS DISCOVERED IN 1801
Ceres has a diameter of 950 km and was discovered in 1801.
It is the closest dwarf planet to the Sun and is located in the asteroid belt. This makes it the only dwarf planet in the inner solar system.
While it is the smallest of the known dwarf planets, it is the largest object in the asteroid belt.
It's less than three times as far from the Sun as Earth – close enough to feel the warmth of the star so the ice can melt and re-form.
Nasa's Dawn spaceship made its way to Ceres after leaving the asteroid Vesta in 2012.
There is great interest in the mission as Ceres is believed to be the record of the early solar system.
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