HOUSTON — NASA astronauts aboard the International Space Station resumed efforts on Oct. 24 to identify the cause of the leak that flooded the helmet worn by European Space Agency colleague Luca Parmitano with water during a mid-July spacewalk.

The station astronauts removed a cooling system pump and small contaminants found in the garment’s Primary Life Support System plumbing. The old fan pump separator and the preserved contaminants, including a 1-cm. piece of plastic, will return to Earth aboard Russia’s TMA-09M crew transport late Nov. 10 with Parmitano, NASA astronaut Karen Nyberg and ISS Russian commander Fyodor Yurchikhin.

The hardware and contaminants will then be flown by NASA transport from the Kazakh landing site to Johnson Space Center, where a Mishap Investigation Board (MIB) hopes to quickly complete its probe of the worrisome incident.

Plans for a 6- to 7-hr. spacewalk to prepare the station’s solar power and Ethernet systems for the arrival of Russia’s Multi-Purpose Laboratory were suspended after 92 min. Largely unable to see or hear, Parmitano made his way by memory and touch back to the U.S. airlock, where he was helped from his spacesuit, while his spacewalking NASA colleague Chris Cassidy gathered tools and equipment.

The five-member MIB was established to determine the root cause, identify contributing factors and recommend changes to the maintenance and use of the space shuttle-era NASA spacesuits as warranted.

An engineering-level investigation also under way has tracked the source of the water that emerged from an air vent at the back of Parmitano’s helmet and flowed over the top of the communications cap secured tightly over his head to the Primary Life Support System (PLSS) that is worn as a backpack. The tightly packed PLSS holds breathing oxygen and CO2 removal hardware as well as a battery power source and a water storage tank for the suit’s water-circulating cooling system.

The compact fan pump separator that was removed from Parmitano’s suit on Oct. 24 circulates breathing oxygen and water coolant throughout the suit, while removing moisture from the air ventilation system and any gases trapped in the coolant lines, said Alex Kanelakos, a NASA flight director involved in the troubleshooting.

“Our engineering teams have identified several different components of the suit with a big fault tree,” said Kanelakos. “This is just one of the components we think could have contributed to the leak. Superficially, the water separator is where we are concentrating our efforts today.”