In a report released today, NASA said that the dangerous water leak that cut Italian astronaut Luca Parmitano's second spacewalk short on July 16, 2013 was partly due to a misdiagnosis of a similar leak detected on his first spacewalk, just one week before.
On July 16, 2013, American astronaut Chris Cassidy joined Parmitano on what was to be the second of two six-hour EVAs (Extra-Vehicular Activity or spacewalk), to prepare the International Space Station for the addition of a new module later in the year. However, just over 90 minutes into the work, Parmitano was forced to return to the airlock when water began leaking into his helmet. Although the amount of water (about a litre and a half) wasn't enough to fill his helmet, the unique way that water behaves in microgravity caused it to cling to him and begin to coat his face. If he hadn't acted quickly to return to the station and remove his helmet, he could have drowned due to just a thin layer of water around his head.
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In a report presented during a media conference today, and summarized online, the Mishap Investigation Board (MIB) determined that "the space suit actually suffered the same failure at the end of EVA 22, performed a week earlier, and this event was not properly investigated which could have prevented placing a crew member at risk a week later during EVA 23."
According to the investigation, the leaked occurred due to some sort of inorganic material blocking up several small holes in a part of the suit called the Fan Pump Separator. This blockage caused water from the suit's cooling system to back up and overflow into the air system and then leak into Parmitano's helmet. The exact cause of the blockage itself is still under investigation (due to the complexity of the suit system), but the report notes that the NASA team's lack of knowledge of this kind of failure, and a subsequent misdiagnosis of the problem when it occurred the first time, contributed to the incident.
The week before, after Cassidy's and Parmitano's first spacewalk, between half a litre and a litre of water was found in Parmitano's helmet when they returned to the ISS. At the time, it was thought to be either a leak from the drink bag that all astronauts have in their suits, or from the liquid-cooled suit the astronauts wear inside the spacesuit. The liquid-cooled suit was dry, so it was ruled out as the source of the leak. Also, Parmitano had reported seeing a small amount of water escaping from the bag's drinking tube while the airlock was being repressurized, caused because his position pressed his chest against the bag. Since the drink bag was found to be empty, and the amount of water in his helmet was roughly what would be found inside the bag, the crew and the ground team concluded that the bag was the problem and it was replaced for Parmitano's second spacewalk.
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Ironically, just a day before the July 16 incident, Parmitano had recorded a short, funny video in response to Karen Nyberg's hair-washing video from the week before. The video shows, in quite the dramatic way, how the water easily clings to Parmitano's head in the station's microgravity environment:
Since the incident, the ISS crew has worked up a fix for all the suits on the station, using absorbent pads and what is essentially a snorkel that would let the astronaut breathe despite their head being coated by water. Fortunately, no similar incidences have happened since, but Parimatino did not have a chance to conduct another spacewalk before he returned to Earth in early November.
(Photo courtesy: Luca Parmitano/ESA/NASA)
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