The two astronauts Terry Virts and Barry Wilmore completed a new spacewalk of more than 6 hours on Wednesday, aimed at continuing the installation of a network of cables and adapters allowing the next modules of SpaceX and Boeing docking at the station.
It was while entering the station's decompression chamber that the astronauts discovered that water had seeped into the right side of Terry Virts helmet.
The infiltration is reminiscent of the incident that had occurred in 2013 with the Italian astronaut Luca Parmitano, who had to interrupt his mission following a major water leak in his spacesuit.
Already last Saturday, the first mission of the astronauts had been launched after several postponements following doubts from NASA as to the suitability of the suits.
The US space agency said that Terry Virts' life was never in danger during the 6:43 mission. However, the astronaut had already mentioned the presence of water in his helmet and gloves during frequent inspections.
Changes have already been made to its equipment, but it appears that NASA has not really been able to locate the problem.
This incident could jeopardize the third and last mission planned for this Sunday, which will aim to complete the installation of the new docking system at the ISS.
The mission aims to allow the USA to completely detach itself from its dependence on Russia for the transportation of men to the ISS. The module will allow the SpaceX and Boeing manned capsules to dock directly at the station.
The next Boeing spacecraft, the CST-100, will carry 7 crew members and will be the first private manned capsule to dock at the station in 2017. The module will be followed by the Dragon V2 capsule from Space X which displays the same transport capacity.