Asteroids are cold rock fragments, usually pieces from larger bodies that broke off during collisions. However, NASA scientists suspected that Vesta was a protoplanet, meaning that it started forming into a planet in the early years of our solar system.
NASA's DAWN mission was designed to collect data and learn about this planet-forming process. The DAWN spacecraft was launched in 2007 and traveled 1.8 billion miles to reach Vesta in 2011.
The DAWN Spacecraft