The British and Irish Meteorite Society

The churning of glaciers spews many space rocks out on to the surface in Antarctica, but compared to elsewhere on Earth, few of them are made of iron.

Based on modelling and lab experiments, scientists say the missing metallic rocks might be burying themselves, by melting the ice as sunlight heats them.

To prove their idea, the team now wants to look for the rocks themselves.

"The study is proposing a hypothesis - these samples should be there. We just have to go and locate them," said Dr Katherine Joy from the University of Manchester, a co-author of the paper published in Nature Communications.

Antarctica contains some of the most productive regions on Earth for collecting meteorites. These small areas of glacial ice are known as meteorite stranding zones, where upward-flowing ice combines with high ablation rates to concentrate large numbers of englacially transported meteorites onto their surface. However, meteorite collection data shows that iron and stony-iron meteorites are significantly under-represented from these regions as compared with all other sites on Earth. Here we explain how this discrepancy may be due to englacial solar warming, whereby meteorites a few tens of centimetres below the ice surface can be warmed up enough to cause melting of their surrounding ice and sink downwards. We show that meteorites with a high-enough thermal conductivity (for example, iron meteorites) can sink at a rate sufficient to offset the total annual upward ice transport, which may therefore permanently trap them below the ice surface and explain their absence from collection data.

Barwellian wrote:Interesting....perhaps another change for Katie to get back meteorite hunting in Antarctica.

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Our experiments centred around subjecting a meteorite encased in a block of ice (400 × 400 × 50 mm) to the radiation from an Oriel Solar Simulator arc lamp (irradiance 1,440 W m−2) that was held at a constant 10 mm above the ice surface and focused onto the englacial meteorite. This was conducted in a (otherwise dark, non-reflecting) temperature-controlled room, with ambient temperature −1 °C.