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Home / Science / The dwarf planet Ceres has a secret ocean of salt water

The dwarf planet Ceres has a secret ocean of salt water



The dwarf planet Ceres, shown in pseudo color, is visible to Occator crater.

The dwarf planet Ceres, shown in pseudo color, is visible to Occator crater.
Picture: NASA / JPL-CalTech / UCLA / MPS / DLR / IDA

Scientists believe that the mysterious bright spots on Ceres, the largest object in the main asteroid belt, are caused by a giant saltwater reservoir underneath the dwarf planet’s crust.

The subsurface ocean is the kind of ocean we would expect to see in the outer solar system, especially on the icy moons in orbit around Jupiter, Saturn, Uranus, and Neptune. United. But according to seven (yes, seven) new articles published in the journal Nature collectionThe sub-surface oceans can also appear on non-asteroid objects, as introduced by Ceres, a dwarf planet in the main asteroid belt between Mars and Jupiter.

Ceres, as the new study shows, is recently active and possibly still, contains a vast underground reservoir and exhibits a form of cryovolcanism (in which groundwater is surface water) never seen in a celestial body. . Subsurface oceans on icy moons, such as Jupiter’s Europa and Saturn’s Enceladus, are kept warm by the tidal interactions generated by their host planets, but the same is not possible. occurs to small asteroid objects in the asteroid belt. For Ceres, this phenomenon is more chemical nature, because the water below the surface is still in a viscous state due to the high salt content.

The wrong image is displayed inside Occator crater.  The pinkish zones indicate the areas in which the brine comes in contact over the surface of the Ceres.

The wrong image is displayed inside Occator crater. The pinkish zones indicate the areas in which the brine comes in contact over the surface of the Ceres.
Picture: NASA / JPL-Caltech / UCLA / MPS / DLR / IDA

The new study, described in articles published in Nature Astronomy, Nature Geoscience and Nature Communications, includes scientists from NASA, the Institute of the Moon and Planets (LPI), University of Münster in Germany, Research Institute. and National Science Education (NISER)) in India, among many others.

At 590 miles wide (950 km), Ceres is the largest object in the asteroid belt. NASA’s Dawn spacecraft visited Ceres 2015-2018, collecting critically important data during the final five months of the mission, when the orbiter swooped to within 22 miles (35 km) of the surface.

High-resolution images sent back to Earth reveal Occator Crater in unprecedented detail. This crater, formed by a giant impact, is the dwarf planet’s most distinguishing feature, measuring 57 miles wide (92 km), which is rather large even by Earth standards. Occator Crater is revealed to be a complex structure, having a central concave covered in a dome-like structure, various cracks and trenches, and bright mineral deposits and arches. Smaller ones are scattered all over the place.

The scene of Occator crater shows Cerealia Facula (B) and Vinalia Faculae (C).

The scene of Occator crater shows Cerealia Facula (B) and Vinalia Faculae (C).
Picture: Nathues et al. Natural Astronomy

That water could have been the cause of the Ceres’ bright surface features that were suspected prior to the Dawn mission, but data collected by the orbiter shows this to be true.

A number of small impact craters on the Ceres point towards a relatively young surface. Occator Crater formed about 22 million years ago, with some of the youngest surface features on Ceres formed just 2 million years ago.

The common feature of the craters is the peak formed in the center. Such a trait forms inside the Occator, but it collapses, creating a depression inside the depression. Then, about 7.5 million years ago, water – or more salt water – rose to the surface, leaking through this collapsing peak. This salt water evaporates, leaving a reflective residue in the form of sodium carbonate – a mixture of sodium, carbon and oxygen. The bright white slot in the center of the Occator, Cerealia Facula, is a remnant of this process.

Similar sediments are found elsewhere in the crater, including a striking feature known as Vinalia Faculae. In these locations, the brine rises to the surface through cracks and grooves.

Close-up of Cerealia Facula (B) and Vinalia Faculae (C).

Close-up of Cerealia Facula (B) and Vinalia Faculae (C).
Picture: Nathues et al. Natural Astronomy

About 2 million years ago, Cerealia Facula reactivated, spewing more salt water, forming a central dome made of bright material. These processes took place about 1 million years ago, and they are probably still going on today, although cryovolcanic processes have weakened significantly over time.

According to the researchers, evaporation and sublimation (when the liquid transforms directly into a gas) forces water to float to the surface, in a cryovolcanism form not found anywhere else in the solar system. Scientists have good reason to believe that this process could exist elsewhere on other seemingly inert bodies.

Guneshwar Thangjam, co-author of Nature Astronomy, said: “The evidence of recent geological activity on Ceres contradicts the general belief that small objects in the solar system are geologically inactive. paper and a researcher from NISER, in one Press Release.

Crucially, the subsurface ocean could have formed by the impact of the Occator crater, but its constant subsidence is caused by salts dissolved in groundwater.

“For the large mine in Cerealia Facula, most of the salt is provided from a bubbling area just below the molten surface due to the crater formation impact about 20 million years ago,” said Carol Raymond, lead author. of Natural Astronomy learn and Dawn’s principal investigator, said in a NASA Press Release. “The impact heat gradually decreases after a few million years; however, the impact also creates large cracks that can reach deep, long-lasting layers, allowing salt water to continue seeping to the surface “.

Bright white deposits and domes inside the Occator crater, formed from the underground geysers below.

Bright white deposits and domes inside the Occator crater, formed from the underground geysers below.
Picture: NASA / JPL-Caltech / UCLA / MPS / DLR / IDA

Ceres has hundreds and possibly thousands of smaller sedimentary sites, most of which are less than 33 feet (10 meters) thick. Spots and pits appear on the surface, also resulting from groundwater movement.

By studying Ceres’s gravity, scientists were able to deduce its internal structure. The saltwater reservoir is located about 25 miles (40 km) below the surface and is hundreds of miles wide. Given that Ceres itself is just 590 miles wide, it’s fair to call Ceres an oceanic world.

It seems that overnight, Ceres has become the tantalizing target of astronomers. With intricate chemistry, liquid water, and the dynamics on the surface and below the surface, it may have existed at some point in its recent history. The task of bringing a probe to the surface suddenly seemed like a very good idea.


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