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Spacewalk aborted by spacesuit water leak
Posted: July 16, 2013

A dangerous leak resulting in a large blob of water weightlessly sloshing inside Luca Parmitano's space helmet forced NASA to abort a planned six-and-a-half-hour spacewalk Tuesday, sending the Italian astronaut, struggling to hear and see clearly, back to the safety of the International Space Station's Quest airlock.

Astronaut Luca Parmitano. Credit: NASA
Fellow spacewalker Christopher Cassidy helped him along and within a little more than a half hour, the airlock was repressurized. Astronaut Karen Nyberg and cosmonauts Pavel Vinogradov and Fyodor Yurchikhin quickly opened the airlock's inner hatch and helped Parmitano get his helmet off, using towels to soak up the free water.

Flight director David Korth praised Parmitano, Italy's first spacewalker, for "grace under pressure."

"As he progressed back toward the airlock, the amount of water he was reporting started to increase and increase," Korth said. "You can imagine, you're in a fishbowl. So go stick your head in a fishbowl and go try to walk around. That's not anything you take lightly.

"Certainly, an EVA is dangerous already, and he did a great job of just keeping calm and cool and making his way back to the airlock."

It's not yet clear what caused the leak. NASA spacesuits feature a built-in 32-ounce drink bag filled with potable water and more than a gallon of water used in the suit's cooling system. Engineers do not believe the drink bag was the culprit, but they do not yet know exactly where the leak originated.

Wherever it came from, it was a serious issue. In the absence of gravity, water tends to pool in blobs and inside the cramped confines of a space helmet, a large amount of water could trigger uncontrolled coughing and, possibly, even drowning.

"Choking or drowning is definitely a possibility" if enough water is present, said Karina Eversley, the lead spacewalk officer at the Johnson Space Center in Houston.

The spacewalk, the second in seven days for Cassidy and Parmitano, began at 7:57 a.m. EDT (GMT-4). The work proceeded smoothly through the EVA's early stages as both men accomplished the initial tasks on their to-do lists.

Then Parmitano ran into a pair of problems. A carbon dioxide sensor in his spacesuit suddenly stopped working and shortly after, he noticed the back of his head felt unusually wet. Problems with CO2 sensors have cropped up in earlier spacewalks and don't normally pose a problem; flight controllers simply monitor suit telemetry on the ground and keep tabs on how the spacewalker feels.

But as Parmitano continued to work, routing cables on the outside of the International Space Station, he felt more and more water pooling in his helmet.

"I don't understand where it's coming from," he said.

"It has to be (your drink) bag," Cassidy replied. "Can you suck it dry?"

A few minutes later, Cassidy peered into his crewmate's helmet for a closeup look, saying "so that stuff on your forehead is not sweat?"

"No it's not."

A few minutes after that, Cassidy told flight controllers in Houston that Parmitano's drink bag almost certainly was empty "so there's something left, like a liter, at the back of his head."

"No, it's less than that," Parmitano corrected. "Half a liter."

"A half a liter at the back of his head," Cassidy called. "Half of a drink bag. That's just a guess on our part."

But the amount of water continued to increase and began to creep around the side of Parmitano's head into the forward part of the helmet.

"I can still hear perfectly, but my head is really wet and I feel it increasing," Parmitano said. A few minute laster, he wondered again, "where's it coming from? It's too much."

"I don't know, it's a lot," Cassidy agreed.

"Now it's in my eyes," Parmitano said.

By that point, flight controllers assessing the problem at the Johnson Space Center in Houston already knew the spacewalk could not continue. In fact, it needed to end as quickly as possible.

"He started reporting it was coming around his ears and getting on the front of his face and it was at that point, per the rules and guidelines, we judged it was in the best interest of the crew and the mission (to) terminate the EVA," Korth said. "It wasn't prudent to try to continue tasks with water accumulating around his ears and the discomfort he had at that point."

Astronaut Shane Kimbrough in mission control passed the decision up to the crew.

"Chris and Luca just for you guys, based on what we heard with Luca saying that water's in his eyes now and it seems to be increasing, we think we're going to terminate EVA case for EV-2," he said. "So Luca, we'll have you head back to the airlock. Chris, we'll get a plan for you to clean things up here and then join him in a minute."

"OK. copy all, Shane," Cassidy said.

And not a moment too soon. By the time the astronauts made it back to the Quest airlock, Parmitano was having trouble seeing, hearing and even talking. The spacewalk ended at 9:29 a.m. when valves were opened to begin repressurizing the outer airlock.

Eight minutes later, the airlock's inner hatch was opened and Vinogradov and Yurchikhin quickly removed Parmitano's helmet, using towels to sop up the excess water. Parmitano appeared in good spirits as he dried off and Eversley said he was none the worse for the scare.

"Luca's doing great," she said. "He's smiling and happy and all the crew is looking at the suits and reporting anything they can to help us investigate the source."

Korth said the carbo dioxide sensor failure may have been a result of the water leak. Parmitano initially speculated the leak involved his drink bag, but there appeared to be more water in his helmet than the drink bag could account for. On top of that, the water didn't taste right.

"Luca says the water tastes really funny, not like our water from the PWD (potable water dispenser), which makes me think ... water out of the PWR (water reservoir)," Cassidy told flight controllers later. Water in the cooling system is laced with iodine to prevent bacteria from building up. "To him, the water clearly did not taste like normal drinking water.

"And the other important thing is when we took his LCVG (liquid cooling and ventilation garment) off, demated that connection, and felt his long underwear right by his belly button, that was all basically completely dry. Some little moisture from sweat, but not to the extent that it would have created the bubble up in his (helmet)."

He was referring to the location of a cooling line inside Parmitano's spacesuit.

Cassidy said the water was concentrated at the back of Parmitano's helmet, "kind of where the vent port is. That region seems to be the source of the water in the back of his head."

Cassidy and Parmitano carried out a spacewalk last Tuesday to begin working through a backlog of station maintenance and assembly tasks. Today's outing was the sixth for Cassidy and the second for Parmitano, the first Italian to walk in space.

The astronauts only accomplished the first two tasks on their spacewalk to-do list. Cassidy completed work at the Z1 truss atop the central Unity module to install a second set of jumper cables that will enable flight controllers to quickly reconfigure electrical loads in the wake of failures that otherwise would require a spacewalk.

Parmitano, meanwhile, began work to complete installation of wiring between the U.S. and Russian segments of the station. Shortly thereafter, the water problem developed and both spacewalkers were told to stand by while flight controllers assessed the problem. Within a few minutes, they were told to head back to the airlock.

None of the remaining items on the crew's spacewalk task list are time critical and flight controllers will assess the crew's timeline to figure out when another attempt can be made to get the work done.

The unfinished tasks include additional cable routing, work to move a wireless camera antenna on the station's power truss and replacement of a camera on the external deck of the Japanese Kibo lab module.

The astronauts also planned to reposition a balky door in a compartment on the power truss that houses electrical gear and to remove insulation blankets from a failed electrical switching unit that will be repaired later using the station's robot arm.

"As far as where we go from here, clearly we have a problem at this point that we don't quite understand," said Kenneth Todd, chairman of the ISS Mission Management Team. "And we're going to take the next day or two and sort through that ... trying to determine what kind of things we can do on orbit and here on the ground to try to get a better understanding of what's going on."

As for when NASA might attempt another spacewalk to complete the unfinished tasks, "we have no time clock that we're working to and certainly when you have an issue like this, you want to make sure you turn over every rock and make sure we've dealt with the issue completely."

Today's spacewalk was the 171st devoted to station assembly and maintenance since construction began in 1998 and the fifth so far this year. Including today's excursion, 112 astronauts and cosmonauts have now logged 1,075 hours and 22 minutes of EVA time outside the station, or 44.8 days.

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