A plane carrying two sick workers rescued from a remote South Pole research station landed in Chile late on Wednesday after a daring effort that involved battling temperatures lower than minus 70 degrees Fahrenheit and round-the-clock darkness, the National Science Foundation said.

The plane, a Twin Otter aircraft, left the foundation’s Amundsen-Scott South Pole Station early on Wednesday morning and arrived in Punta Arenas, Chile, at 9:41 p.m., the foundation said on its Facebook page.

The two patients will be taken for medical care that was not available at Amundsen-Scott, the foundation said. It would not reveal details of their conditions. Both patients are seasonal employees of Lockheed Martin Antarctic Support Contract, which offers operations and research support for the United States Antarctic Program, the foundation said.