European Space Agency astronaut Luca Parmitano joined in a NASA investigation of the leak that allowed one to two liters of water to seep into his space suit and helmet during a spacewalk with NASA astronaut Chris Cassidy on Tuesday. The planned six to seven hour excursion was halted after 92 minutes by the worrisome water globs that formed close to his eyes, nose and mouth.

Luca Parmitano just before space suit problems. The European Space Agency astronaut became the first Italian to walk in space on July 9. Photo Credit/ESA

The watery intrusion could have caused the 36-year-old Italian test pilot to choke, possibly even drown, said Karina Eversley, NASA’s lead spacewalk officer.

Parmitano and Cassidy carried out a similar six hour spacewalk on July 9, while  wearing the same space suits but experiencing none of the difficulties.

The U. S.-led International Space Station mission management team monitored a NASA investigation into several possible leak sources, including Parmitano’s 32 ounce in suit drink bag as well as the cooling system that circulates water through narrow tubes in his space suit undergarments.

Eversley and David Korth, the lead NASA flight director during the spacewalk, characterized the drink bag as an unlikely leak source.

NASA’s Kenny Todd, the MMT chairman, said none of the remaining activities on Tuesday’s abbreviated spacewalk are considered urgent.  The excursion will be re-scheduled once the leak investigation is complete, he said.

The seepage forced Parmitano to stop working after he finished an extension of power and data cables to a mechanical anchor on the station’s Russian segment for Canada’s robot arm. The mechanical limb is often used during spacewalks to move astronauts around the outside of the station.

Meanwhile, Cassidy was working with electrical cabling to establish a secondary power channel for a range of critical space station systems, including solar power and thermal control system components. The changes Cassidy made will permit astronauts inside the station to switch station systems to a backup solar power source without a spacewalk.

As he worked, the Italian astronaut noticed a problem with the CO2, or carbon dioxide, sensor in his suit. The device monitors the level of the harmful gas in the breathing air of the protective air tight garment.

Parmitano continued to work, pausing again when he felt moisture on the back of his head. The worrisome water accumulation continued as Cassidy moved toward his colleague to investigate.  Cassidy spotted water around Parmitano’s face, prompting the NASA Mission Control team to suspend further work.

The water continued to mass in his helmet as Parmitano moved toward the safety of the station’s airlock. He reported difficulties seeing and hearing.

“Clearly, we have a problem that at this point we don’t quite understand,”  Todd told a NASA sponsored news briefing.  “We will take the next day or two and sort through that — probably do a little bit of troubleshooting on orbit while the team (on the ground) works through the fault tree and tries to determine what kinds of things we can do to try to get a better understanding of what is going on.”