Dawn is breaking yet again – on some new astrogeology, that is. The Dawn spacecraft has been stalking the dwarf planet Ceres in the asteroid belt between Mars and Jupiter, and it’s been transmitting some beautiful images back to Earth for some time now. Included in those are a peculiar feature that scientists have frustratingly struggled to get their head around: What the heck are those white, bright patches in one of its craters? Through the process of elimination, the mystery may have finally been solved. Perhaps disappointingly to many, they are probably a big dollop of salt.
There have been a few explanations as to what these patches are. As CNET reports, the possibilities range from the scientifically plausible to the hilariously bizarre: exposed ice, water vapor, ice volcanoes and even the headlights of a giant spacecraft...
Ceres has long been an object of scientific curiosity. As the NASA mission website states, it is often compared to the giant asteroid Vesta, a dynamic, terrestrial world much like the rocky members of the inner Solar System. Ceres is even larger than Vesta, earning it the accolade of a “dwarf planet”. However, it is less dense and has a thin atmosphere containing water vapor. Scientists think that Ceres may be in fact an icy body more akin to the most distant members of the Solar System, such as Pluto.
To the disappointment of those who thought Ceres may indeed be a planet-sized spacecraft with headlights, Dawn’s principle investigator, Chris Russell, announced at the European Planetary Science Congress (EPSC) in Nantes on Monday that these reflective patches are likely to be a huge salt deposit.
As for what type of salt it is, members of Dawn’s research team aren't sure yet, but they are certain the patches are not ice of some kind. Water ice patches were a reasonable guess, considering the strong likelihood of there being a subterranean ocean underneath the surface.
Significantly, if the presence of salts within the crater is confirmed, it would indicate that Ceres has a dynamic, active surface. According to the Dawn research team, the salts were likely to be derived from the interior of the icy-rocky mass before somehow making their way to the surface.
It is pertinent here to make a comparison to the salty water found on Mars. The presence of both water vapor and salt on Ceres, along with the thrilling possibility that the dwarf planet could contain more freshwater than our very own planet Earth, suggests that it may be home to a primitive form of life. It must be said that in the cases of both Mars and Ceres, salty water does not guarantee that there is life thriving on either worlds, but in dry environments on Earth that show some presence of briny water – such as the Atacama desert – microbes are often found.
Check out Chris Russell's opening address to the EPSC below, where he outlines the findings in full.