Washington - An Italian astronaut had a leak in his helmet while doing a spacewalk at the International Space Station Tuesday, forcing an early end to the outing, Nasa said.
"A little more [than] one hour into the spacewalk, Luca Parmitano of the European Space Agency reported water free-floating behind his head inside his helmet," the US space agency said.
Parmitano and fellow US astronaut Chris Cassidy made it back into the orbiting research lab at about 13:29 GMT, according to Nasa television.
Cassidy said his colleague was doing "okay".
Parmitano was rushed into the space station Quest airlock where crew members removed his helmet.
"You can see some of the water floating away that had built up inside Luca's helmet," a commentator said as live images were broadcast on Nasa TV.
It was unclear what caused the situation.
"Neither astronaut was in serious danger throughout," the Nasa commentator said, but added the cause of the leak was "not easily identifiable".
The purpose of the spacewalk, the second of two planned this month, was to prepare the ISS for a new Russian module and to make some repairs.
The outing lasted one hour 32 minutes, Nasa said. It was supposed to last six hours and 15 minutes.
Parmitano, who is the first Italian astronaut to walk in space, was making the second spacewalk of his career.