Giant asteroid fragment makes impact

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Giant asteroid fragment makes impact

The University of Cardiff press release is reproduced below:

A first-ever discovery of a fragment from a giant meteorite which crashed to Earth millions of years ago could cause a re-think about asteroid collisions with our planet.

Dr Iain McDonald of the School of Earth Ocean & Planetary Sciences was among the international research team who identified the 25cm sized fragment, found in a frozen magma pool at the bottom of the giant Morokweng crater in South Africa. The unique discovery, which has just been published in Nature, gives a direct insight into what was happening in the solar system 144 million years ago.

The researchers found the fossilised meteorite fragment 766m below the surface whilst helping a company searching for copper and nickel in the giant Morokwong crater in South Africa. The international team comprised researchers from South Africa, America, Canada and the Universities of Cardiff and Glasgow.

Dr McDonald, who led the UK component of the research team, said: "This was a huge stroke of luck, as had the borehole been sited just a metre away, it may have missed the object altogether. For the first time it is possible to hold in your hand an actual piece of a giant asteroid that hit the Earth. This intact fragment may tell us a lot more about the insides of asteroids than we currently know."

Scientists have long believed that large asteroids or comets are obliterated by the enormous temperatures created when they collide with the Earth. Smaller impact craters of less than 4 kilometers diameter have been found to contain meteorite fragments. It was thought that any asteroid generating a crater larger than 4 kilometres in diameter would be completely destroyed, but the new discovery challenges that view.

Morokweng is a very large crater of 70 kilometres diameter, and the fragment’s survival suggests the asteroid struck the Earth at a lower speed than has been assumed in the past.

Dr McDonald, who analysed the composition of the fragment, revealed a further twist to the story of the meteorite, of a type called an ordinary chondrite.

He said: "Morokweng is no run of the mill meteorite. It shows some striking differences when compared with other known meteorites, such as the absence of iron-nickel metal. It appears that the Morokweng meteorite may have come from a very different part of the parent asteroid than other ordinary chondrites which currently fall to earth."

To highlight its unique status, fragments of the asteroid have gone on display at the Science Museum's Antenna news gallery from Thursday 11th May.

Source: University of Cardiff Press Release