The dwarf planet Ceres – long thought to be a barren space rock – is an ocean world with reservoirs of seawater beneath its surface, which showed the results of a major reconnaissance service on Monday.
Ceres is the largest object in the asteroid belt between Mars and Jupiter and has its own gravitational force, which allows the Nasa Dawn spacecraft to capture high-resolution images from its surface.
Now, a team of scientists from the United States and Europe have analyzed images transmitted from the orbiter, captured about 35 km (22 miles) from the asteroid.
They focused on the 20-million-year-old Occator crater and determined that there was an “extensive reservoir” of brine beneath the surface.
Several studies published Monday in the journals Nature Astronomy, Nature Geoscience and Nature Communications also shed further light on the dwarf planet, which was discovered in 1801 by the Italian polymath Giuseppe Piazzi.
Using infrared imaging, one team discovered the presence of the composite hydrohalite – a material that is common in sea ice, but has so far never been observed from Earth.
Maria Cristina De Sanctis, of the Istituto Nazionale di Astrofisica of Rome, said that hydrohality was a clear sign that Ceres once had seawater.
“We can now say that Ceres is a kind of ocean world, like some of the moons of Saturn and Jupiter,” she told AFP.
The team said the salt deposits looked like they had built up in the last 2 million years – the blink of an eye in space time.
This suggests that the brine may still be rising from the interior of the planet, which De Sanctis said may have implicit implications in future studies.
“The material found on Ceres is extremely important in terms of astrobiology,” she said.
“We know that these minerals are all essential for the emergence of life.”
Julie Castillo-Rogez, of the Jet Propulsion Laboratory of the California Institute of Technology, said the discovery of hydrohalite was a ‘smoke gun’ for sustained water activity.
“That material is unstable on the surface of Ceres, and therefore needs to be inserted very recently,” she said.
In a separate paper, US researchers analyzed images of the Occator crater and found that the mounds and hills could form when water formed by the impact of a meteor on the surface froze.
The authors said their findings showed that such aquatic processes “extend beyond Earth and Mars, and have been active on Ceres in the geologically recent past”.
