The Polar Star, the nation’s only heavy icebreaker, departed last week from Pearl Harbor for Antarctica to resupply scientists stationed there, according to the U.S. Coast Guard.

The 13,500-ton Polar Star is a cutter with 75,000 horsepower, according to the Coast Guard, and is headed to Antarctica to resupply the National Science Foundation’s McMurdo and Amundsen-Scott South Pole stations.

Its crew spent several days in Honolulu to stock up and will stop in the South Pacific in late December before crossing the Southern Ocean for Antarctica. The Polar Star will then establish a channel through 15 miles of ice in McMurdo Sound, Antarctica, sometimes up to 10 feet in thickness. It is expected to arrive in early January.

“Operation Deep Freeze, the U.S. military’s contribution to the National Science Foundation-managed, civilian U.S. Antarctic Program, is unlike any other U.S. military operation,” said Capt. Michael Davanzo, commanding officer of Polar Star in a press release. “It’s one of the most difficult U.S. military peacetime missions due to the harsh environment and extreme remoteness in which it is conducted.”

The USAP is managed by the NSF on behalf of the U.S. government to support world-leading scientific research in and about Antarctica. The Polar Star is homeported in Seattle.