Buzz Aldrin, the former U.S. astronaut and the second person to walk on the moon, was in stable condition after being evacuated from the South Pole to a New Zealand hospital because of a medical problem, a U.S. agency and his tour company said.
Aldrin, 86, arrived by cargo plane in Christchurch, New Zealand, early on Friday local time, according to the U.S. National Science Foundation, which manages the U.S. Antarctic Program.
He was visiting the South Pole as part of a tourist group when his condition deteriorated, the tourism company White Desert said in a statement.
Aldrin had fluid in his lungs but was in good spirits and responding well to antibiotics, the company said. He would be kept in the hospital for observation.
Aldrin was a fighter pilot during the Korean War before joining the U.S. astronaut program. On July 20, 1969, he stepped on the moon about 20 minutes after Neil Armstrong had taken the historic first step.
Their moonwalk was part of the Apollo 11 lunar landing was watched by a then-record television audience of 600 million people.
Aldrin last year helped to launch a research institute at the Florida Institute of Technology aimed at paving a path toward Mars exploration and settlement.
On Tuesday, he wore a T-shirt saying "Destination: Mars" as he prepared for the trip to Antarctica, according to photographs on his Twitter account.
(Reporting by David Ingram in New York; Editing by Bernadette Baum and Bill Trott)