CAPE CANAVERAL, FL -- Astronauts on the International Space Station completed a spacewalk Sunday despite the appearance of water inside an astronaut's helmet, NASA reported.

In a tweet, the space agency said astronaut Terry Virts experienced water inside his helmet, just as he did Wednesday, but "it's a known issue; no concern."

The spacewalk lasted five hours and 38 minutes, NASA said.

"Crews have now spent a total of 1,171 hours and 29 minutes conducting space station assembly and maintenance during 187 spacewalks," the agency said in a release.

NASA previously said the suit worn by NASA astronaut Virts has a history of "sublimator water carryover." Water in the sublimator cooling component can condense when the suit is repressurized after a spacewalk, causing a small amount of water to push into the helmet, NASA said.

NASA said International Space Station managers had "a high degree of confidence" in the suit.

On the upcoming spacewalk, Virts and Barry Wilmore installed antennas to provide data to visiting vehicles and deploy 400 feet of cable along the edge of the station.

Virts said he first noticed traces of fluid and dampness in his helmet Wednesday while he was waiting for the crew lock cabin to repressurize.

He and Wilmore had been outside the space station for nearly seven hours working on the station's robotic arm and performing some maintenance.

Virts immediately alerted fellow astronaut Samantha Cristoforetti about the water, and she alerted Mission Control in Houston.

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Astronauts Finish 5-hour Spacewalk