|This new map of Vesta, which uses a Mollweide projection, reveals the asteroid’s geological history. NASA/JPL-Caltech/Arizona State University|
For 15 months between 2011 and 2012, the Dawn spacecraft orbited the asteroid called Vesta, snapping high-resolution pictures of the cratered, potato-shaped rock. Scientists then spent another two and a half years poring over the images and piecing together the geology written on Vesta’s surface. Now, a team led by planetary scientist David Williams of Arizona State University has compiled that information together into this beautiful map, which they’ve published online for the December issue of the journal Icarus.
Vesta was forged within the cloud of dust and debris that formed the solar system about 4.5 billion years ago. During its lifetime, Vesta was pelted with smaller asteroids and rocks, which left a multitude of craters. But according to the researchers, there were three impacts in particular that shaped Vesta’s geological history. The most recent collision happened sometime between 120 million and 390 million years ago, forming the Marcia crater seen near the center of the map.
Two earlier impacts struck Vesta’s south pole more than one billion years ago between 200 million and one billion years apart, making the Veneneia and Rheasilvia craters, which are each about 300 miles in diameter. These collisions were so big that they reshaped the asteroid, leading to its elongated shape today, Williams says.