NASA's Dawn spacecraft became the first craft to orbit a dwarf planet Friday as it reached Ceres after a nearly eight-year, 5-billion-kilometre journey, the space agency said according to dpa. Dawn has already visited the giant asteroid Vesta, spending 14 months in 2011 and 2012 in orbit, and is the first spacecraft to orbit two extraterrestrial bodies. First spotted in 1801, Ceres is located in the asteroid belt between Mars and Jupiter. As the probe spirals closer and closer to Ceres, scientists plan to collect images and data to help determine its size and composition. It will be at its closest point to Ceres by December. "By studying Vesta and Ceres, we will gain a better understanding of the formation of our solar system, especially the terrestrial planets and most importantly the Earth," principle investigator Carol Raymond said this week. Of special interest are a number of "puzzling bright spots," on the surface of Ceres, Raymond said. These highly reflective spots may contain ice or salts, she said. From start to finish the mission will cost 473 million dollars. NASA's previous missions - such as Pioneer 11 that launched to Saturnin 1973 - gathered data along the way from multiple extraterrestrial bodies, but did not enter orbits other than the destination planet. Upon completion of the mission and after fuel sources run dry, the Dawn probe is likely to stay in orbit around Ceres for hundreds of years, NASA researchers said.
