spacetoday.net: Dawn shows Vesta to be remnant protoplanet

Posted: Mon, May 14, 2012, 5:22 AM ET (0922 GMT)
Dawn orbiting Vesta illustration (NASA/JPL)

Scientists analyzing data from NASA's Dawn spacecraft orbiting the large asteroid Vesta have concluded that the body has some of the key characteristics of a planet, suggesting it is a protoplanet left over from the solar system's formation. Observations of the asteroid show that it is a differentiated body, featuring an iron core with a radius of 110 kilometers as well as a mantle and crust. That leads scientists to conclude that Vesta is a protoplanet whose evolution into a full-fledged planet was stopped before it could evolve into a larger world. Scientists also confirmed that a class of meteorites that comprise six percent of meteorites found on Earth are from Vesta. Observations of Vesta by Dawn will continue through late August, when the spacecraft will depart for its other planned destination, the asteroid/dwarf planet Ceres, arriving there in 2015.