German astronomers have discovered a long-sought missing chunk of matter from one of the solar system’s more mysterious objects, the proto-planet Vesta, they announced Friday.

They trained telescopes on an asteroid known as 1999 TA10 and managed to assess its unique chemical makeup. The asteroid, which is one to two kilometres in diameter, comes within a few million kilometres of earth during its orbit.

The chemical make-up, with extraordinarily low levels of iron and a high concentration of wollastonite and ferrosilite, makes it practically certain that it is the missing chunk of Vesta’s mantle long sought by astronomers.

The discovery was made by scientists at the Max Planck Institute for Solar System Research at Katlenburg-Lindau in Germany using images from a telescope in Hawaii.

Vesta, discovered two centuries ago, is 525 kilometres in diameter and one of the two biggest objects in the asteroid belt.

It is believed to be the remnant of a proto-planet that was knocked apart in space collisions and never assembled itself into a big globe thanks to gravitational forces, as other planets did 4 billion years ago.

The scientists said in an article in the journal Icarus that it seemed TA10 had been blown off the side of Vesta and had whirled off into space. The theory that Vesta took a big hit has been contested in the past because no fragment of its mantle had ever been found.

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