The dwarf planet Ceres – as long as it is believed to be a barren space rock – is an oceanic world with seawater reservoirs beneath its surface, the results of a major exploration mission showed on Monday.
Ceres is the largest object in the asteroid belt between Mars and Jupiter and has its own weight, enabling the Nasa Dawn spacecraft to capture high-resolution images of its surface.
Now a team of scientists from the United States and Europe have analyzed images transmitted by the orbiter, captured about 35 km (22 miles) from the asteroid.
They focused on the 20-year-old Oktator crater and determined that there is a “wide reservoir”; of brine beneath its 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 by the Italian polymath Giuseppe Piazzi in 1801.
Using infrared images, a team discovered the presence of complex hydrohalite – a common material on sea ice, but which until now had never been observed outside of Earth.
Maria Cristina De Sanctis, from the National Institute of Astrophysics in Rome said hydrohalitis was a clear sign that Ceres used to have sea water.
“We can now say that Ceres is a kind of oceanic world, such as some of the moons of Saturn and Jupiter,” she told AFP.
The team said the salt deposits looked like they had built up within the last 2 million years – the blink of an eye in time in space.
This suggests that brine may still be contagious from inside the planet, something De Sanctis said could have profound implications for future studies.
“The material found in Ceres is extremely important in terms of astrobiology,” she said.
“We know these minerals are all essential to the emergence of life.”
Writing in an accompanying comment article, Julie Castillo-Rogez, of the Institute of California’s Aircraft Propulsion Laboratory, said the discovery of hydrohalitis was a “smoking weapon” for continued water activity.
“This material is unstable on the surface of Ceres, and therefore must have been placed very recently,” she said.
In a separate paper, U.S.-based researchers analyzed images of the Octator crater and discovered that its hills and hills may have formed when water was extracted from the impact of a frozen meteor on the surface.
The authors said their findings showed that such water-freezing processes “extend beyond Earth and Mars, and have been active in Ceres in the recent geological past”.