Vesta - an asteroid in 3D
Dawn spacecraft orbiting Vesta
What might asteroid Vesta look like? In a new animation, researchers at the German Aerospace Center (Deutsches Zentrum für Luft- und Raumfahrt; DLR) have recreated the asteroid in 3D. In the animation, the asteroid is irregularly shaped, has a slight indentation at its South Pole and numerous impact craters. In July 2011, after a four year journey, NASA's Dawn spacecraft will reach the asteroid, which circles the Sun in the main asteroid belt between the orbits of Mars and Jupiter. This will be like taking a journey into the past because Vesta is a celestial body that has not changed much since the formation of the Solar System.
Test run for the arrival of the Dawn spacecraft in the asteroid belt
"It will be the first time that we get so close to such an ancient celestial body," says Ralf Jaumann from the DLR Institute of Planetary Research. "With Vesta, we have the opportunity to learn what happened when the planets were first formed from a cloud of dust." The asteroid was discovered by German astronomer Heinrich Olbers on 29 March 1807. Spectral measurements performed using ground-based telescopes suggest that the celestial body could consist of a firm crust of rocks of various compositions, a mantle and a core - the same as the Earth-like planets. Shortly after its formation 4.6 billion years ago, Vesta is suspected to have been completely molten. In the following 50 million years, the asteroid cooled down and the rocks separated according to their various densities, causing the heavier material to move towards the interior. "After this process, however, not much more happened on Vesta," explains Jaumann, a planetary geologist.
Pieces of asteroids found on EarthPrincipally in the Sahara and the Antarctic, explorers have come across meteorites whose chemical compositions match the components of Vesta. This is what the spectral analyses of the meteorites and of Vesta suggest. "We are fairly sure that we have samples of Vesta here on Earth," says Jaumann. Planetary research scientists believe that, at some time in the past, another asteroid collided with Vesta, resulting in a 13-kilometre-deep crater on Vesta along with 50 new small asteroids, with numerous tiny fragments finding their way to Earth. So far, of the multitude of meteorites found on Earth, only a few can be classified as belonging to the Moon, Mars and Vesta; the origin of others remains uncertain. The fact that some samples can clearly be classified as originating from Vesta is a stroke of luck for Solar System research.