Is Ceres' Mysterious Bright Dome an Ice Volcano?

After a year of speculation since NASA’s Dawn mission arrived in orbit around dwarf planet Ceres, we may be coming close to answer as to what is causing its mysterious bright spots inside the famous Occator Crater.

“Before Dawn began its intensive observations of Ceres last year, Occator Crater looked to be one large bright area,” said Ralf Jaumann, planetary scientist and Dawn co-investigator at the German Aerospace Center (DLR) in Berlin. “Now, with the latest close views, we can see complex features that provide new mysteries to investigate.”

Revealed at the 47th annual Lunar and Planetary Science Conference in The Woodlands, Texas on Tuesday, this enhanced color view (pictured top) inside the 57 mile-wide crater reveals a wonderfully detailed observation of a dome-like structure. The dome, nestled inside a smooth-walled pit, exhibits fractures and is surrounded by blotchy white clusters.

These are the highest-resolution pictures of this famous region captured so far as Dawn was carrying out low mapping orbits yet, coming within 240 miles from the small world’s surface.

“The intricate geometry of the crater interior suggests geologic activity in the recent past, but we will need to complete detailed geologic mapping of the crater in order to test hypotheses for its formation,” said Jaumann.

Further work is needed to fully understand what internal mechanisms are driving Occator’s strange geology, but from these observations, the domed structure certainly appears to be volcanic in origin. However, if confirmed, this is a very different kind of volcano than what we are familiar with on Earth.

Long before Dawn entered Ceres orbit, it was known that Ceres, which lives in the asteroid belt between the orbits of Mars and Jupiter, has significant quantities of water in the upper layers of its surface. The bright spots inside Occator were also observed, leading to speculation that Ceres’ geology is driven by cryovolcanoes. Assuming significant quantities of volatiles (ices) inside Ceres are gently heated by the dwarf planet’s interior, these chemicals could be erupting through the surface layers. Over time, a dome may form, cracking and resurfacing the crust.

This finding ties in with other recent discoveries on Ceres. Primarily, there are less craters than would be expected for such an ancient body; perhaps ongoing icy processes like cryovolcanism is constantly resurfacing Ceres. Also, ground-based observations of the bright spots have shown daily variations. Even possible vapor has been spied by Dawn around the vicinity of Occator — a sign of sublimating ice.

In other findings summarized at Tuesday’s meeting, planetary scientists said that Dawn’s VIR instrument had detected water inside the young 6 mile-wide Oxo Crater in the northern hemisphere of Ceres. Also, the dwarf planet has a rich variety of mineral variations across its surface. VIR analysis on another crater called Haulani has revealed a very different material composition below the surface. “The diversity of materials implies either that there is a mixed layer underneath, or that the impact itself changed the properties of the materials,” said VIR instrument lead scientist Maria Cristina de Sanctis, at the National Institute of Astrophysics, Rome.

Of course, Ceres wasn’t the first asteroid belt body Dawn has visited. The spacecraft also spent 14 months from 2011-2012 in orbit around massive asteroid Vesta, allowing mission scientists to carry out direct comparisons between the two bodies.

Read more at Discovery News