National Public Radio: The mission: Travel more than 600 miles across the Arctic Ocean, in temperatures down to 40 degrees below zero. It’s the Catlin Arctic Survey, a British expedition to the North Pole. Its goal is to collect data to help scientists determine how fast the sea ice is disappearing. Pen Hadow is the exhibition leader of a three-person team. It’s day 35, and the team is about 450 miles away from the North Pole. The polar explorers are using equipment ranging from a mobile radar …