NASA terminates spacewalk following leak into astronaut's helmet

A spacewalk outside the International Space Station was canceled on Tuesday, after more than a quart of “funny-tasting” water leaked into an astronaut’s helmet. 

The cause of the dangerous leak is still under investigation, NASA officials said at a press conference on Tuesday afternoon.

The spacewalk began ahead of schedule at 7:57 EDT Tuesday morning and began to go awry when Italian astronaut Luca Parmitano reported that his carbon dioxide sensor was malfunctioning. He then reported a water bubble burgeoning behind his head. His teammate, U.S. astronaut Chris Cassidy, assessed the situation and told mission control that between 1 and 1½ liters of water had begun to accumulate.

Since water in space forms globs, Parmitano could not hear, speak, or see as the water seeped into his helmet, NASA officials said.

NASA aborted the walk an hour and 32 minutes into the mission, and the pair re-boarded the ISS at 9:29 a.m. The trip outside had been scheduled to last 6 hours and 15 minutes.

“We have not seen a problem like this before,” said Karina Eversley, a NASA spacewalk officer, at the conference, adding that drowning or choking was a real possibility had the mission not been quickly terminated. “This was a very serious issue.”

She also said that Parmitano is in good condition: “Luca is doing great. He’s smiling and happy.”

The scheduled spacewalk was the second of two for the astronaut pair. They spent 6 hours and 7 minutes outside last week to make repairs on the station and to prepare it to dock with a Russian module. The astronauts had planned to finish the remaining work on today’s walk. 

Parmitano was wearing the same spacesuit Tuesday that he wore during the previous walk, which went as planned.

NASA officials said that they had ruled out the 32-ounce drinking water bag as the source of the leak, but said that they are still investigating other causes. Another possible source is the spacesuit’s cooling system, which holds a gallon of water. To prevent bacteria buildup, that water is tinged with iodine, which could explain the “funny” water taste that Parmitano reported, NASA officials said.

The carbon dioxide sensor’s malfunction is likely related to the water leakage, they added.

Spacewalks, which are a difficult and high-risk process, have at times been troubled. In 2004, a walk outside the ISS was aborted after 14 minutes, when an oxygen tank on an astronaut’s Russian-made spacesuit failed. Since the spacesuit had a backup air supply, the astronaut, NASA’s Mike Fincke, was not in danger.

Still, most spacewalks are uneventful. The aborted walk today was the 171^st walk performed to maintain the ISS, which has been occupied for almost 13 years. 

NASA officials said that the abbreviated mission would still count for the two astronauts as a spacewalk. That makes Tuesday’s walk Parmitano’s second spacewalk. Last week, he wore a red, white, and green flag affixed to his spacesuit when he became the first Italian astronaut ever to make a spacewalk. This was Cassidy’s sixth spacewalk.

“I will soon depend on this cumbersome suit to survive outside the Station,” wrote Parmitano on his blog, before his first walk.