A month trapped in Antarctic ice has ended for Australia’s supply ship Polar Bird, freed from the close pack ice of Prydz Bay early today after a round-the-clock rescue operation by the icebreaker Aurora Australis.

The long and arduous task of extracting Polar Bird began on Friday when the ship was able to move under its own power for about 35km to the north. At the same time Aurora was forcing a passage through openings in the ice between the ships.

The ships were within 5km of each other when a wind change on Saturday temporarily stopped the rescue effort and caused an ice build-up which blocked Polar Bird’s progress.

Following a frustrating and difficult wait, a further wind change to the south allowed Aurora to work through the final passage of ice, taking eight hours to break through the last three ship-lengths.

After clearing ice around Polar Bird, Aurora used a cable to pull the vessel free. A period of towing ended when the cable broke, but by late Sunday afternoon Polar Bird was able to move independently in the wake of Aurora.

“Finding a way through the ice was like doing a giant maze with thousands of optional routes. If we had not had use of helicopters to sort the leads from the dead ends, we would still be in the ice,” Aurora’s Voyage Leader Greg Hodge said today.

By 7am the ships were moving freely to the northeast in open pack ice.

After completion of passenger transfers between Aurora and Davis station later today, the ships will travel together until completely free of the pack ice and then make their separate ways to Hobart.