Thursday, March 1, 2012

Gigantic Antarctic crack mapped for the first time

Sydney Morning Herald: In a scene straight out of a science-fiction disaster movie, space agency NASA has revealed what a vast crack across Antarctica looks like up close. The 2004 disaster movie The Day After Tomorrow opened with a the Antarctic iceshelf cracking before extreme global weather, and now NASA has it live and on YouTube.

In October 2011, researchers flying in NASA's Operation IceBridge campaign made the first detailed, airborne measurements of a major iceberg calving event while it was in progress. By February, IceBridge's team had mapped the crack in Antarctica's Pine Island Glacier in a way that allowed glaciologists to fly through the icy canyon.

The animation was created by draping aerial photographs from the Digital Mapping System - a still camera with very precise geolocation ability - over data from the Airborne Topographic Mapper, a scanning laser altimeter that measures changes in the surface elevation of the ice.

Both instruments were flown on NASA's DC-8 research aircraft and the data was collected on October 26 last year.

The crack formed in the ice shelf that extended from one of West Antarctica's fastest-moving glaciers. The path of the crack in the animation stretched roughly 30 kilometres in length (the actual crack was much longer), with an average width of about 80 metres. It was 250 metres at its widest.

The canyon ranged from 50 to 60 metres deep, with the floor being roughly at the water line of the Amundsen Sea....

NASA’s DC-8 flies across the crack forming across the Pine Island Glacier ice shelf on Oct. 26, 2011. The ice shelf is in the midst of a natural process of calving a large iceberg, which it hasn’t done since 2001. Credit: Jefferson Beck/NASA

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