The Origin of the Steineisen Meteorites
An international team led by Richard Greenwood from the British Open University in Milton Keynes has determined the origin of the various main groups of Steineisen meteorites.
Meteorites offer scientists a glimpse into the early days of the solar system. The composition of the cloud of matter from which the earth and the other inner planets emerged more than 4.5 billion years ago has been preserved in them. According to their composition, researchers distinguished different types of meteorites.
Only about 1.5 percent of all meteorites belong to the Steineisen meteorites. The olivine crystals known as pallasite were previously assumed to come from the boundary layer between the metallic core and the silicate-rich crust of an asteroid. The origin of the mesosiderites - a structure of silicates and nickel-iron - was assumed to be on the asteroid 4 Vesta, from where they were released during a violent collision with another asteroid. However, these assumptions have not yet been confirmed.
By redetermining the combination of oxygen isotopes in the meteorites, Greenwood's team of scientists has now been able to confirm the assumptions. According to this, pallasites and meosiderites come from two different sources: the mesosiderites probably from the asteroid 4 Vesta, which a planned Nasa mission could check on site as early as next year. The homeland of the Pallasite, however, remains unknown. But the main representatives of this group are probably all splinters from the same mother body.
