Story highlights Spacewalk last more than five hours; crews have spent more than 1,171 hours spacewalking Astronaut Terry Virts found a small amount of water inside his helmet

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.

Italian astronaut Samantha Cristoforetti examines Terry Virts' helmet.

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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.

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H2O in spacewalker's helmet