NASA cut short a spacewalk on Friday at the International Space Station after one of the astronauts reported water in his spacesuit helmet, the U.S. space agency said.
Tim Peake, who on the mission became the first astronaut from Britain to walk in space, and U.S. astronaut Tim Kopra, had finished the primary goal of their outing when Kopra reported a water bubble had formed in his helmet.
"So far, I'm OK," Kopra assured everyone. Later, he said the water bubble was 4 inches long and getting thicker. "I'm doing good," he repeated.
NASA stressed that the situation was not an emergency and insisted neither spacewalker was in danger. Indeed, Kopra took time to thank everyone for their help as the air lock was repressurized. Their crewmates inside waited anxiously with towels to mop up the water, believed to have leaked from the cooling loop in Kopra's suit.
Ending the spacewalk two hours early was a precaution, NASA said.
The astronauts planned to use a syringe to take a water sample and retrieve the helmet absorption pad to determine what may have prompted the moisture to form.
NASA tightened its flight rules after a spacesuit worn by Italian astronaut Luca Parmitano leaked during a spacewalk in July 2013, nearly causing him to drown.
Kopra, who was making his third spacewalk, and Peake had replaced a failed voltage regulator in the station's power system shortly after leaving the station's airlock at around 8 a.m. ET.
They were scheduled to spend more than six hours outside the station, a $100 billion research laboratory that flies about 250 miles above Earth, on other maintenance chores.