The giant asteroid Vesta more closely resembles a small planet or the moon than other asteroids, data returned by NASA’s Dawn spacecraft show.
Images taken by the Dawn, which has been orbiting Vesta since last year, provide key clues into the early universe when the asteroid formed and show it began its life as a planetary building block.
Results of the report appeared in the journal Science on Thursday.
The 4.56-billion-year-old asteroid has a rare iron core, and a crust and mantle like a planet, forming in a similar way to the Earth and its moon. It likely once harboured a sub-surface magma ocean, a feature that often leads to the formation of layers that form planets.
Vesta is also the largest source of meteorites that reach Earth, providing scientists with the first up-close look of the source of such space rocks. The meteorites’ composition matches that of Vesta, which scientists said provides 6 per cent of Earth’s meteorites.
Dawn, which was launched in 2007 by the U.S. space agency, is to offer insights into the beginning of the universe by examining rocky objects that date to the time when planets were forming in the solar system.
After examining Vesta, Dawn will continue on to the dwarf planet Ceres elsewhere in the asteroid belt.