US Coast Guard Cutter Healy, a medium icebreaker, is limping back to its homeport in Seattle after suffering a machinery space fire on Aug. 18, the Coast Guard announced on Tuesday. When the fire broke out, Healy was underway on a combined science and national security mission in the Arctic. The operation has been canceled.

“Healy was 60 nautical miles off of Seward, Alaska, en route to the Arctic when an electrical fire was reported at 9:30 p.m. A fire team disconnected the affected motor, and the fire was confirmed extinguished by 9:56 p.m. The cause of the fire is currently unknown,” read a statement from the Coast Guard. “Due to the fire, Healy’s starboard propulsion motor and shaft are no longer operational, and the ship is transiting back to its homeport in Seattle for further inspection and repairs.”

USCGC Healy, commissioned in 1999, is one of only two US deepsea icebreakers. The other, USCGC Polar Star, a heavy icebreaker, is more than 40 years old and is kept operating by scavenging parts from her decommissioned sister ship, Polar Sea. The fire on the Healy has, effectively disabled half the US deepsea icebreaking fleet.

In comparison, Russia has a fleet of 32 polar icebreakers. Finland has eight, Sweden has seven and Canada has six.

Last year, US Coast Guard received an appropriation to build three new heavy polar icebreakers, followed by the construction of three new medium polar icebreakers. Unfortunately, the first heavy icebreaker, dubbed a Polar Security Cutter, will not be delivered until 2024.

Thanks to Irwin Bryan for contributing to this post.