Ceres is a dwarf planet orbiting the Sun in the asteroid belt, between Mars and Jupiter, which has been imaged for the first time by NASA investigators.
While the Hubble Space Telescope was used to examine the largest body in the main asteroid belt once before, creating an image of higher resolution than Dawn's, this new image taken by Dawn on Dec. 1 is the spacecraft's best image of its future destination.
Astronomers sometimes refer to Ceres as an "embryonic planet," as researchers currently believe Ceres was once a developing world, whose growth was hampered by the gravitational influence of Jupiter.
Ceres is approximately 590 miles in diameter, and is composed largely of rock and ice. Observations using the orbiting observatory revealed the body is mostly round, shaped by the influence of gravity over billions of years. The equator was measured to be wider than the diameter measured pole-to-pole.
The Dawn spacecraft was launched by NASA in September 2007 to study Ceres and an asteroid, Vesta. The vehicle is currently heading toward its rendezvous with Ceres, scheduled for April 2015. When the image was taken on December 1, 2014, the observatory was about 740,000 mile from its final destination. This is about three times the average distance between the Earth and the Moon.
"Now, finally, we have a spacecraft on the verge of unveiling this mysterious, alien world. Soon it will reveal myriad secrets Ceres has held since the dawn of the solar system," Marc Rayman from Jet Propulsion Laboratory, and chief engineer and mission director of the Dawn mission, said.
The $446 million mission will be the first visit to a dwarf planet by spacecraft from Earth. The observatory will be captured by gravity from Ceres in March 2015. The New Horizons spacecraft, headed toward the dwarf planet Pluto, will fly past that system four months later.
Ceres was the first asteroid discovered, by Italian astronomer Giuseppe Piazzi, on January 1, 1801, and was later re-classified as a dwarf planet. This one member of the asteroid belt comprises roughly one-quarter of all the mass in the field. Still, Ceres has just seven percent of the mass of Pluto.
The giant asteroid is large enough to exhibit a differentiated core, in which lighter materials are found on the outside of the body, while denser components fell toward the center. There is even evidence the mantle of Ceres may be composed of water ice.
"Astronomers estimate that if Ceres were composed of 25 percent water, it may have more water than all the fresh water on Earth. Ceres' water, unlike Earth's, would be in the form of water ice and located in the mantle, which wraps around the asteroid's solid core," NASA officials wrote on a page detailing characteristics of the giant frozen body.
The new image of Ceres shows the dwarf planet in a resolution of just nine pixels. Although the picture itself may not provide much in the way of aesthetics, it was the final calibration test of the camera as the observatory approaches its main target.
