LONDON - The first British-led expedition to gather meteorites in the Antarctic has returned with a haul of 36 space rocks.

Manchester University’s Dr Katherine Joy was dropped in the deep field with British Antarctic Survey guide Julie Baum for four weeks. The pair spent their days near the Shackleton mountains running across the ice sheet in skidoos looking for out-of-place objects. The meteorites ranged from tiny flecks to some that were as big as a melon. Some two-thirds of the meteorites in the world’s collections have been picked up in the Antarctic. It’s the contrast of black on white that makes the continent such a productive hunting ground. “As soon as you spot a black rock you know. You dart towards it and your heart picks up a beat,” Dr Joy told BBC News. “They look black because they’re burnt up as they come down through Earth’s atmosphere. They have a very characteristic exterior colour, and they have a kind of cracked surface where that exterior has expanded and contracted during the violent atmospheric entry.”

Other nations have long sent expeditions to the polar south to look for space rocks. The US and Japan have been doing it regularly since the 1970s.China, South Korea, Italy, and Belgium also frequently despatch teams. But this was the first all UK mission, funded by the Leverhulme Trust, and it means the 36 samples will all now come back to Britain for investigation. Meteorites trace their origin to the asteroids and smaller chunks of rocky debris left over from the formation of the Solar System 4.6 billion years ago.

 

As such, they have much to tell us about the conditions that existed when the planets came into being.

Not only does the black-on-white contrast make for easier prospecting in the Antarctic, but hunters also get a helping hand from the way the ice sheet moves. Meteorites that crash in the continent’s high interior are buried and transported towards the coast, ultimately to be dumped in the ocean. But if this conveyor happens to run into a barrier on the way - such as a range of mountains - the ice will be forced upwards and scoured by winds to reveal its cargo. Expeditions will therefore concentrate their searches in these special “stranding zones”. And although the places visited by Dr Joy and Ms Baum had not been explored previously, they had very good reason to be optimistic when they set out. The Manchester-BAS venture was a trial ahead of another deployment in the next field season that will try to target specific types of objects that seem systematically to be underrepresented in Antarctic finds. These are the iron meteorites.