Bright spots on Ceres ID'd, but now new mystery surfaces
Thursday, December 10, 2015, 12:14 PM - Knock one Ceres mystery down and another pops up in its place. The strange bright spots seen in craters across its surface have now been identified, however other findings reveal a potentially distant origin for this dwarf planet.
Bright spots yield up their secrets
NASA's Dawn spacecraft has been orbiting Ceres since March 6, 2015, and now, just 10 months later, the science the probe has been sending back is producing some amazing new revelations about this dwarf planet.
First, the bright spots on Ceres' surface, most notably along the base of Occator crater, in the northern hemisphere, have been identified by a team of scientists as hexahydrite, a type of magnesium sulfate similar to Epsom salt.
False-colour image of Occator crater and its collection of bright spots. Credit: NASA/JPL-Caltech/UCLA/MPS/DLR/IDA
The Nature study, led by Andreas Nathues of the Max Planck Institute for Solar System Research, examined the various bright spots that dot Ceres - both inside impact craters and existing on their own - using different camera filters, and then compared their results with various materials under similar filters in the laboratory. While the spots are apparently not composed all of one material, hydrated magnesium sulfates (water-saturated salts made of magnesium, sulphur and oxygen) were a notable find.
The source of these salt deposits, according to the researchers, is very likely to be found underneath the surface of Ceres.
"The global nature of Ceres' bright spots suggests that this world has a subsurface layer that contains briny water-ice," Nathues said in a NASA statement.
While the higher-resolution imagery Dawn is currently taking, now that it has reached its Low Altitude Mapping Orbit (LAMO), may offer even more information to either strengthen or challenge this evidence, another mystery about this dwarf planet has surfaced.
Was Ceres one of Pluto's neighbors?
In a separate study published in Nature this week, led by Maria Cristina De Sanctis, of the National Institute of Astrophysics in Rome, Dawn's instruments spotted evidence for ammonia-rich clays on Ceres' surface.
This is a particularly important find because Ceres - the largest object in the asteroid belt - is far too close to the Sun for ammonia ices to form and persist. The only place we know of for these ammonia ices to form and stay stable is out far out in the solar system, in the vicinity of Neptune's orbit.
Now, according to the researchers, this could simply be a case of these ammonia ices forming near Neptune and then migrating inwards to eventually be incorporated into Ceres.
On the other hand, this finding could also imply that Ceres itself is not a native to the asteroid belt, but instead formed out in the Kuiper Belt, just beyond Neptune, alongside other dwarf planets like Pluto, Haumea, Makemake and Orcus, just to name a few.
Are they related? Images courtesy: NASA/JPL-Caltech (Ceres), NASA/JHUAPL/SwRI (Pluto/Charon)
The new images and instrument readings taken during Dawn's LAMO may shed even more light on this mystery as well.
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