Using this new technique, the team took high-resolution images of Ceres’s surface, which revealed over 130 glowing white spots, usually residing in the dwarf planet’s craters. Dawn scientists announced earlier this year, for example, that Occator Crater at times contains a layer of haze presumably created by volatile material subliming into space from the bright spots.
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“Our data are consistent with the presence of hydrated magnesium sulfates in the brightest spot of the crater Occator”, Martin Hoffmann and Andreas Nathues, two members of the research team that produced the study, told Mashable via email.
Researchers speculate that water ice comes from a hidden ice sheet underneath Ceres’ rocky crust, which gets exposed every time an impact with a space object occurs.
This is the brightest spot on Ceres, located in the Occator crater. Red corresponds to a wavelength range around 0.97 micrometers (near infrared), green to a wavelength range around 0.75 micrometers (red, visible light) and blue to a wavelength range of around 0.44 micrometers (blue, visible light). But scientists working with the spacecraft’s measurements have remained relatively tight-lipped on the subject, waiting for Dawn to inch closer and closer to the surface of Ceres before making a call. The spots are mostly linked to impact craters and are much brighter compared to the surface of Ceres as a whole. Although another study released today hints that Ceres has little if any water on its exterior, together the findings suggest that the small world may harbor significant amounts of water ice just below its surface. Subsequent investigations led to the conclusion that they were salt, not ice.
The mysterious bright spots on Ceres may no longer be so mysterious.
“I’m not yet fully convinced that ammoniated minerals are definitely there rather than some other choices like brucite”, Rivkin said. The video also shows Occator crater on Ceres.
As of this week, Dawn has reached its final orbital altitude at Ceres, approximately 240 miles (385 kilometers) and the surface of the dwarf planet. “Consequently, we think that this material originated in the outer cold solar system”, lead author Maria Cristina De Sanctis, a scientist at the National Institute of Astrophysics in Rome, said, in a statement.
In 2014, Herschel Space Observatory observed tenuous wisps of water vapor around Ceres.
Nathues and colleagues have now used data from Dawn’s Framing Camera to analyse the spots. Some people said that they were highly-reflective water ice, others believed that they were salt deposits or outcrops of cryo-volcanic activity, while some even went far enough to say that they were military bases of alien civilizations.
(Demoted dwarf planet Pluto is perhaps the most famous of these Kuiper Belt Objects.) Smaller, ammonia-rich chunks would have been more easily dragged into the inner solar system, eventually joining with the other chunks that would form Ceres and becoming incorporated into the body.
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“The presence of ammonia-bearing species suggests that Ceres is composed of material accreted in an environment where ammonia and nitrogen were abundant”. Their incorporation into Ceres’ surface during its formation suggests that the dwarf planet formed out there, before migrating into the main asteroid belt.
