Dawn spacecraft begins study of asteroid Vesta

Space.com : NASA’s Dawn spacecraft, launched in September 2007, arrived last month at the asteroid Vesta and will spend a year circling it before moving on to arrive at the even larger asteroid Ceres in 2015. The first spacecraft to visit an asteroid in the asteroid belt between Mars and Jupiter, Dawn will study Vesta in four phases from different orbits. Each orbit should yield surface images in visible and IR wavelengths from the mapping spectrometer on board; the images will allow the science team to produce geologic and compositional maps of Vesta’s surface. Ultrasensitive measurements of the spacecraft’s motion, made using radio signals, will help researchers better understand Vesta’s gravity field. Ceres and Vesta were chosen because they are two contrasting protoplanets, Ceres being icy and Vesta rocky. Ultimately, by studying those two large bodies in the asteroid belt, researchers hope to gain more information about the formation of the solar system.