NASA Produces the First Ever Geological Map of an Asteroid

The NASA mission DAWN spent all of 2012 orbiting 4 Vesta, the 2^nd largest asteroid in the asteroid belt. DAWN is equipped with a camera and several spectrometers in order to map the shape and surface composition of the asteroid to a m scale resolution. Vesta is 512 km in diameter and the observations of this mission are that it is much more similar to the larger terrestrial planets than other asteroids.

Compositional and mineralogical mapping of the surface of Vesta has identified different geological units across the surface, and allowed a geological timeline to be determined. Relative and absolute ages of the different units have been calculated from the distribution of craters across the surface, and it can be seen that Vesta has undergone several large impact events 2 and 3 billion years ago.

This compositional map also provides a geological context for a group of meteorites called the Howardite-Eucrite-Diogenite (HED) meteorites. These are the volcanic and igneous rocks which have fallen to the Earth’s surface that sample the crust of Vesta. They were excavated from the protoplanet’s surface during the large historical impacts.

The main objectives of the DAWN mission are to characterise the two largest objects in the asteroid belt, as they provide information about the earliest processes and conditions in the solar system. The study of asteroids is key to our knowledge of planetary formation, and the origins of life.