NASA's Dawn spacecraft has begun approaching Ceres ahead of a historic March arrival at the mysterious dwarf planet.
Dawn has officially entered the Ceres approach phase, after emerging from behind the sun relative to Earth and thus coming back into reliable communication range. The probe is now about 400,000 miles (640,000 kilometers) from Ceres and is cruising toward the 590-mile-wide (950-kilometer-wide) object at 450 mph (725 km/h), NASA officials said.
By the end of January, Dawn's photos will be the best ever captured of the dwarf planet, NASA says.
Dawn should enter orbit around Ceres — the largest object in the main asteroid belt between Mars and Jupiter — on March 6. When that happens, the spacecraft will become the first ever to orbit two different unexplored solar system bodies. (Dawn circled the protoplanet Vesta, the asteroid belt's second-largest object, from July 2011 through September 2012.) [Photos: Asteroid Vesta and NASA's Dawn Spacecraft]
Mission team members, and space scientists around the world, are eager to see Ceres up close.
"Ceres is almost a complete mystery to us," the $466 million Dawn mission's principal investigator, Christopher Russell of the University of California at Los Angeles, said in a statement. "Ceres, unlike Vesta, has no meteorites linked to it to help reveal its secrets. All we can predict with confidence is that we will be surprised."
While Ceres and Vesta reside in the same general neighborhood, they appear to be quite different from each other. For example, the 325-mile-wide (525-kilometer-wide) Vesta is thought to be a dry body, while Ceres possesses an icy mantle and might even harbor a subsurface ocean of liquid water. Some researchers even suggest that Ceres might be capable of supporting life as we know it.
Dawn launched in 2007 on a mission to learn more about the solar system's early days, and the planet-formation process, by studying Vesta and Ceres. The probe's prime mission is scheduled to end in July 2015.