Tucson, Ariz. -- NASA's Dawn spacecraft continues to close in on the dwarf planet Ceres and has obtained navigational images of more than half of Ceres using its framing camera. These images are just under the resolution obtained by the Hubble Space Telescope 10 years earlier. Scientists at the Planetary Science Institute and elsewhere have been studying these images and have been able to discern all of the albedo features identified by Hubble over that portion of Ceres observed by Dawn.
"Reproducing the Hubble observations is important to understanding the nature of Ceres' surface," said PSI Research Scientist Jian-Yang Li, who led the Hubble mapping effort of Ceres. "The recent detection of episodic water vapor near Ceres' surface by the Herschel Space Observatory at a longitude observed by Dawn might arise from activity that could change Ceres' surface over time."
In addition to confirming the Hubble observations other features are also becoming visible. “Already, the (latest) images hint at first surface structures such as craters," said Andreas Nathues, lead investigator for the framing camera team at the Max Planck Institute for Solar System Research, Gottingen, Germany.
There are also indications that at least one large extended structure might exist. "If it is tectonic, it should provide insight into the interior processes of this small planet," said Mark Sykes, CEO of the Planetary Science Institute and a co-investigator on the mission. “Models of Ceres interior suggest there could be subsurface oceans and an outer ice-rich layer.”
Dawn images will exceed the resolution of Hubble when it next observes Ceres on January 26, 2015. "We are brimming with questions and excitement as we move closer and closer to this new world," Sykes said.
Dawn will be captured by Ceres' gravity on March 6, 2015, marking the first time a spacecraft has ever orbited two solar system targets. Dawn orbited and studied the protoplanet Vesta for 14 months. Both Vesta and Ceres are located in the asteroid belt between Mars and Jupiter. Ceres is the largest object in the asteroid belt, with a diameter of about 950 km, and is the only object that is round as a consequence of its own gravity, making it a geophysical planet.
The Dawn mission to Vesta and Ceres is managed by NASA’s Jet Propulsion Laboratory for NASA's Science Mission Directorate. The framing cameras have been developed and built under the leadership of the Max Planck Institute for Solar System Research and funded Max Planck Society, DLR, and NASA. The Planetary Science Institute operates Dawn’s Gamma Ray Neutron and Detector instrument.