By Sid Perkins
The autonomous underwater vehicle, stuffed to its gills with scientific instruments, motors steadily through the frigid, sunless sea. Sensors on board the 6.8-meter-long craft are constantly on alert, testing the water for minute variations in salinity and temperature. As the vehicle cruises beneath a ceiling of ice hundreds of meters thick, its sonar observes above it a rugged topography of ice unlike any previously seen.
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Although scientists had previously deployed autonomous underwater vehicles (AUVs) beneath free-floating ice, until last year they’d never sent an AUV under one of Antarctica’s ice shelves. On that 50-kilometer maiden voyage, the craft got a tantalizing look at one of the world’s most unexplored environments—one where seas increasingly warmed by modern climate change come into contact with ancient ice flowing off the continent.