PASADENA, Calif. - The dwarf planet Ceres was long believed to be a barren rock, but new images from NASA’s Dawn mission proves otherwise.
Ceres is located in the main asteroid belt between Mars and Jupiter and has a gravitational pull strong enough to shape its structure. NASA’s Dawn spacecraft was able to give scientists groundbreaking, high-definition images of the mysteriously bright spots on its surface.
When the mission initially concluded in October of 2018, scientists determined from the images that the bright spots were deposits made from compounds of sodium, carbon and oxygen. These spots were predicted to have originated from liquid that filtered through the planet’s surface and evaporated, leaving behind a “highly reflective salt crust.”
What remained a mystery, however, was where this liquid came from.
Now, after analyzing collected data and studying the dwarf planet’s gravity, NASA scientists concluded that the liquid was originally from a deep reservoir of salt-enriched water, otherwise known as brine. They found that Ceres’ internal structure featured a brine reservoir that stretches for hundreds of miles and is about 25 miles deep.
The new research highlighted Ceres’ 57-mile-wide Occator Crater — which houses a majority of the dwarf planet’s bright spots — and confirmed that Ceres is a water-rich world similar to the icy moons in our solar system.
“Dawn accomplished far more than we hoped when it embarked on its extraordinary extraterrestrial expedition,” said Marc Rayman, mission director of NASA’s Jet Propulsion Laboratory in Pasadena, California, in an Aug. 10 press release. “These exciting new discoveries from the end of its long and productive mission are a wonderful tribute to this remarkable interplanetary explorer.”
The researchers found that the bright areas are relatively young, with some less than 2 million years old. They also discovered that the geologic activity that produced the sodium carbonate deposits is still ongoing.
Ceres’ surface should quickly dehydrate salts bearing water within a couple hundred years, but the images captured of Dawn show the salts still have water, which means the deposits must have reached the surface relatively recently.
While similar features reminiscent of Earth-like ice mountains have been found on Mars, the discovery of them on Ceres marks the first time traces of water have been found on a dwarf planet, according to NASA.