Dawn Journal | June 29Dawn is continuing to unveil a Ceres of mysteries at the first dwarf planet discovered. The spacecraft has been extremely productive, returning a wealth of photographs and other scientific measurements to reveal the nature of this exotic alien world of rock and ice. First glimpsed more than 200 years ago as a dot of light among the stars, Ceres is the only dwarf planet between the sun and Neptune.
Dawn has been orbiting Ceres every 3.1 days at an altitude of 2,700 miles (4,400 kilometers). As described last month, the probe aimed its powerful sensors at the strange landscape throughout each long, slow passage over the side of Ceres facing the sun. Meanwhile, Ceres turned on its axis every nine hours, presenting itself to the ambassador from Earth. On the half of each revolution when Dawn was above ground that was cloaked in the darkness of night, it pointed its main antenna to that planet far, far away and radioed its precious findings to eager Earthlings (although the results will be available for others throughout the cosmos as well). Dawn began this second mapping campaign (also known as “survey orbit”) on June 5, and tomorrow it will complete its eighth and final revolution.
The spacecraft made most of its observations by looking straight down at the terrain directly beneath it. During portions of its first, second and fourth orbits, however, Dawn peered at the limb of Ceres against the endless black of space, seeing the sights from a different perspective to gain a better sense of the lay of the land.
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