"It's a known feature," Kanelakos said during a NASA broadcast Friday.
Virts estimated the amount of water in his helmet Wednesday at one-half of an ounce. That did not include the water that moistened the absorbent pad at the back of his head, or that might have escaped when his helmet was removed.
As much as 2 ounces of water could condense like this and get into the helmet without causing a problem, Kanelakos said.
Astronaut Butch Wilmore's suit - which is new - functioned perfectly.
Virts and Wilmore are in the process of routing hundreds of feet of cable, needed before the arrival of new docking ports later this year that will be used by crew capsules still under development by Boeing and SpaceX. NASA expects these commercial capsules to start ferrying station astronauts in 2017.
During Sunday's spacewalk, the astronauts will install another 400 feet of cable as well as two antennas. About 364 feet of power and data lines were laid during the first two spacewalks, last Saturday and Wednesday.
Kanelakos noted that this series of complicated spacewalks is "the most that we've ever done in a row since space shuttle."
NASA wants to wrap up the work as soon as possible; that's because Wilmore's 5 1/2 -month mission ends March 11.