The latest images of Ceres, captured by NASA's Dawn spacecraft as it comes ever closer to its rendezvous with the dwarf planet, are the sharpest yet obtained, scientists say.
Taken as Dawn moves toward entering orbit around Ceres on March 6, the new and improved images have raised more questions about the dwarf planet and its surface than they have provided answers, say scientists affiliated with the Dawn mission managed by NASA's Jet Propulsion Laboratory in Pasadena, Calif.
"As we slowly approach the [orbital] stage, our eyes transfixed on Ceres and her planetary dance, we find she has beguiled us but left us none the wiser," says Chris Russell at UCLA, principal investigator of the Dawn mission. "We expected to be surprised; we did not expect to be this puzzled."
The new images, taken on Feb. 12 from about 52,000 miles with a resolution of around 5 miles per pixel, have brought the dwarf planet's craters, and some mysterious bright spots, into better focus, JPL reported.
In earlier photos taken at a greater distance, scientists were puzzled by a large white spot on its surface. The new photos show that single white spot is actually made up of a number of white spots, but scientists still have no clue as to why parts of the surface of Ceres should be so highly reflective.
Dawn is approaching Ceres, at around 600 miles wide the largest body in the asteroid belt between Mars and Jupiter, after spending time in 2011 and 2012 examining Vesta, a 326-mile-wide giant asteroid that is the second-largest space rock in the belt.
By gathering data on Ceres and comparing it to what has been discovered about Vests, scientists say they hope to gain new understanding of the early formation of the solar system.
The $446 million Dawn mission was launched in 2007.
Ceres was the first asteroid to be discovered, spotted in 1801 by Italian astronomer Guiseppe Piazzi.
At first thought to be another solar system planet, it was then termed an asteroid and has since been classified as a dwarf planet, the only one in the inner solar system.
It is thought to account for a full third of all the mass in the asteroid belt.
In 2014 emissions of water vapor were detected from several areas on the surface of Ceres, suggesting the possible existence of an internal liquid ocean under its icy surface.
