NASA's Dawn probe is slowly closing in on its final destination and new observations of the dwarf planet Ceres are revealing a fascinatingly complex little world.
VIDEO: Dwarf Planet Ceres is Amazing
"As we slowly approach the stage, our eyes transfixed on Ceres and her planetary dance, we find she has beguiled us but left us none the wiser," said principal investigator Chris Russell, of the University of California, Los Angeles (UCLA), in a NASA news release. "We expected to be surprised; we did not expect to be this puzzled."
These most recent images were acquired on Feb. 12 from a distance of around 52,000 miles (83,000 kilometers) as the robotic spacecraft slowly spirals in on its target. In this highest-resolution ever view of Ceres, each pixel represents 4.9 miles (7.8 kilometers).
IN DEPTH: NASA Spacecraft Ready to Unlock Ceres' Mysteries
As opposed to a rapid deceleration burn that would be carried out by spacecraft using conventional rockets for propulsion (in the case of NASA's Cassini probe, for example), Dawn is taking the slow-yet-steady approach using ion engines. This form of propulsion allows continuous thrust for long periods of time, using tiny quantities of fuel. So rather than flying full-speed at Ceres, Dawn has slowly ‘danced' into formation around Ceres, allowing us many weeks of a gradually sharpening view as the mission creeps up on the solar system's innermost dwarf planet.
Of particular interest to planetary scientists remains the bright patches of landscape - including the one particularly bright feature shown in the image above (right frame). Other bright features are present, but the origin of this discrete spot is keeping astrogeologists guessing.
ANALYSIS: Craters Pop as NASA's Dawn Probe Approaches Ceres
During Dawn's journey through the asteroid belt - the region of space between the orbits of Mars and Jupiter - the Hubble Space Telescope detected plumes of water around Ceres. Could these plumes be associated with geysers leaking a sub-surface ocean of water into space, as observed at Saturn's moon Enceladus and Jupiter's moon Europa? If so, these bright features may highlight venting cracks in Ceres' crust where water is being forced from the dwarf planet's interior, venting to space as vapor and freezing on the surface as an icy residue, appearing as bright patches on the cratered surface.
But as these images are showing, Ceres is covered in craters, suggesting it has an ancient rocky surface, not a continually recycled icy surface like Enceladus of Europa. So perhaps these white areas are signs of cryovolcanism?
For now, this is all speculation, but as dawn approaches Ceres orbit, many of these mysteries will likely soon be revealed.