Polarstern research vessel returned to Bremerhaven, Germany, on 12 October after a yearlong drift across the Arctic. By Chelsea Harvey, E&E NewsOriginally published by E&E NewsThe largest Arctic science expedition in history came to a close yesterday, as the German research vessel Polarstern sailed into the port at Bremerhaven, Germany.The Polarstern spent the past year drifting across the Arctic Ocean, frozen into the sea ice at the top of the world.