U.S. astronauts complete successful ISS spacewalk after helmet scare

A pair of U.S. astronauts successfully completed their third and final spacewalk in just eight days Sunday to update the International Space Station (ISS), under the shadow of a water buildup in a spacesuit helmet at the end of their previous spacewalk.

U.S. space agency NASA expected the spacewalk, which began at 6: 52 a.m. EDT (GMT 1152), to take about six hours and 45 minutes, but astronauts Terry Virts and Barry Wilmore ended up needing only five hours and 38 minutes.

During their spacewalk, the duo completed installing 400 feet ( 122 meters) of cable and a series of antennas and communications equipment that will allow future U.S. private crewed spacecraft to dock with the ISS, the space agency wrote in a blog post.

The astronauts also completed one additional task to retrieve a bag to cover equipment on the outside of the ISS, it added.

The spacewalk was the third in eight days for NASA, and was the third for Virts and the fourth for Wilmore.

During their previous two spacewalks, the duo spent nearly 14 hours outside the ISS deploying cables, lubricating parts at the end of the space station's robotic arm and doing other preparation work.

At the conclusion of Wednesday's spacewalk, Virts reported seeing a small amount of water floating free in his helmet after he was back in the station's Quest airlock and the repressurization of the airlock had begun.

NASA's mission managers gave a "go" Friday to proceed with Sunday's spacewalk after determining that Virts' helmet issue posed no threat to the astronauts.

They said Virts' spacesuit has a history of releasing a tiny amount of water into the helmet when the environment around the suit is repressurized following its exposure to vacuum during a spacewalk.

The problem was reminiscent of another helmet water leak that nearly drowned Italian astronaut Luca Parmitano during a spacewalk in July 2013. NASA managers believed that the two incidents were not related and expressed "a high degree of confidence" that Virts ' spacesuit "systems are all in good shape."

During Sunday's spacewalk, both astronauts said that their spacesuits functioned perfectly, but Virts reported a small amount of water in helmet again afterward during repressurization of the station's Quest airlock, just like what had happened Wednesday.

"It's a known issue," NASA said on Twitter. "No concern." Endite