Flight engineer Luca Parmitano, on the second space walk of his career, is the first Italian to take a spacewalk.
The report said a little over an hour into the space walk from the orbiting International Space Station, Parmitano said there was water floating behind his head inside his helmet. NASA said the water was not an immediate hazard, but Mission Control decided to end the walk early.
Flight Director David Korth ordered flight engineer Chris Cassidy of NASA and Parmitano to return to the Quest airlock and re-enter the ISS. NASA said.
Cassidy performed cleanup procedures before returning to the airlock.
He reported it looked like around a half-liter of water had leaked into Parmitano's helmet, possibly from the suit's drink bag.
The spacewalk officially began at 7:57 a.m. EDT, and ended at 9:39 a.m. when the airlock was repressurized, NASA said. The extravehicular activity lasted 1 hour, 32 minutes.
Cassidy and Parmitano finished the installation of bypass jumpers "to provide power redundancy to critical station components," a NASA statement said.
The two astronauts had planned to route additional cables for a Russian Multipurpose Laboratory Module scheduled to arrive later this year, "replace a video camera on the Japanese Exposed Facility experiment platform, relocate wireless television camera equipment, troubleshoot a balky door cover over electronic relay boxes on the station's truss and reconfigure a thermal insulation over a failed electronics box that was removed from the station's truss last year," NASA said.