It’s currently the middle of winter in the South Pole, where only 48 people live at the Amundsen-Scott research station. There, contractors and scientists monitor the atmosphere, observe climate change, and conduct subatomic particle and astronomy research.

The remote scientific facility is cut off from the rest of the world, with no access to hospitals. People who get sick at the Amundsen-Scott station visit medical personnel on site. Some people have even treated themselves—in 1999, a doctor named Jerri Nielsen biopsied her own cancerous lump and administered her own chemotherapy. But now, The Washington Post reports, at least one worker is sick—and the National Science Foundation (NSF), which oversees the facility, is sending two tiny planes to the Earth’s southernmost point to evacuate them.

Due to privacy reasons, we don’t know why, exactly, the individual—a contractor for Lockheed Martin—is in need of treatment. (A second worker reportedly might also need rescuing, too.) However, we do know that it’s highly unusual for residents of the Amundsen-Scott research station to be evacuated at any time of the year, let alone in the dead of winter. 

Due to the region’s dark skies and freezing temperatures, it’s nearly impossible for planes to fly in and out of the station; normally, no flights take place between February and October. In fact, only two rescue missions have occurred in the Amundsen-Scott station's six-decade history. The first was in 2001, for a physician named Ron Shemenski, who had pancreatitis. Two years later, in 2003, environmental health and safety officer Barry McCue developed a gallbladder infection and needed to be flown out.

Even in severe cases, sick or injured people are known to stay at the Amundsen-Scott station until warmer weather arrives. In 2011, a 58-year-old woman named Renee-Nicole Douceur suffered a stroke but remained at the station for two more months until a scheduled cargo plane came in. In short, evacuating someone from the South Pole isn’t a decision made lightly.

Two winter-proof bush planes operated by Canadian polar service firm Kenn Borek have been dispatched south from Calgary, Canada. Each one carries a pilot and co-pilot, an engineer, and a medic. According to the NSF, the planes are specially designed to operate in extremely low temperatures and are able to land on skis. “As there is no tarmac runway at the South Pole, the aircraft must land in total darkness on compacted snow,” the NSF wrote in a release.

One of the planes will land at the British research station Rothera on Adelaide Island and wait there to provide any necessary search-and-rescue operations. The other craft will fly roughly 1500 miles to the Amundsen-Scott research station, where they’ll hopefully arrive as early as June 19. 

The flight’s risky because of the dark and the cold—and also because it’s a 10-hour trip, and the planes are loaded with only 12 or 13 hours of fuel.  You can track their flight online—and send good thoughts to the rescuers, the sick individuals, and everyone else who’s involved in the daring mission.

[h/t The Washington Post]