Last summer astronaut Luca Parmitano came perilously close to drowning in space after more than a liter of water leaked into his helmet.
Today NASA officials said they are still trying to figure out what went wrong.
The near-drowning occurred July 16 about one hour into Parmitano's second spacewalk.
Forty-four minutes into the walk, the Italian astronaut noticed the back of his head was wet. Ten minutes later he reported the amount of water was increasing. By the time mission control decided to abort the mission 23 minutes later, large droplets of water were starting to cover Parmitano's eyes, nose and ears as he made his way toward the air lock. Somehow 1 1/2 liters of water had made it into his helmet.
In a report about the incident released Wednesday, members of the NASA appointed Mishap Investigation Board said the cause of the near-drowning could be traced to contamination in a portion of the spacesuit called the fan pump separator.
The contaminant is an inorganic silicate that clogged some of the holes in the pump and kept water from flowing through it. In pictures it looks like a small blob of shaving cream. The clog created a backup of water, which lead to some of the water flowing into the air system and ultimately into Parmitano's helmet, the board concluded.
But how that contamination got there, they still cannot say.
After dozens of interviews with people involved in the mission, the board also found that the spacesuit had failed once before, at the end of Parmitano's first spacewalk on July 9.
After returning to the space station, Parmitano and his fellow crew members noticed his helmet had filled with about half a liter of water, but because they saw no signs of the water during the spacewalk, they thought it must have gotten in there during repress -- perhaps through a drink bag that Parmitano inadvertently pressed with his chin.
According to the report, the ground team accepted this explanation without much discussion. And therein, the authors say, lies the problem.
"When presented with the suggestion that the crew member's drink bag leaked out the large amount of water that was found in [Parmitano's] helmet, no one ... challenged this determination or investigated further," they write. "Had that conclusion been challenged, the issue would likely have been discovered prior to [the next spacewalk] and the mishap would have been avoided."
Agency officials said they don't plan to do any more spacewalks until they have gotten to the root of the problem.
"If we haven't gotten to root causes, we will postpone all [spacewalks] on the books until the teams are done," Michael Suffredini, International Space Station program manager, said at a news conference Wednesday. "But I have high confidence we will be ready in the June time frame."
Suffredini said NASA is planning two spacewalks for late summer, although the dates have not been locked down.
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