By Eric Mack, CNET.com, SouthFloridaReporter.com, Oct. 4, 2015 – NASA has spent months probing ever-sharper images of dwarf planet Ceres sent back from the Dawn spacecraft. Now, the space agency thinks it has a pretty good guess about the source of a series of mysterious bright spots reflecting back from the surface of the largest object in the asteroid belt.
“We believe this is a huge salt deposit,” Dawn’s principal investigator Chris Russell told a crowd of scientists Monday at the European Planetary Science Congress in Nantes, France, in a talk that was posted online Thursday. “We know it’s not ice and we’re pretty sure it’s salt, but we don’t know exactly what salt at the present time. ”
This may come as something of a surprise to many watching the drama on Ceres unfold who guessed that the spots were reflective ice. That’s because the dwarf planet is believed to harbor a subsurface ocean that could have been exposed and then frozen by asteroid impacts.
As a geologist, I immediately thought these were diapiric salt eruptions,just like salt domes on earth, the lower density salt flows like toothpaste up due to pressure and ends up on the surface. No surprise there.