On the 16th July 2013 Italian European Space Agency (ESA) astronaut Luca Parmitano embarked on EVA-23, the second spacewalk of his career. The first, according to Parmitano, “went perfectly from the beginning to the end”, so when he and NASA astronaut Chris Cassidy embarked on the second exactly a week later there was nothing to suggest anything untoward was about to happen.
In reality, however, what Parmitano was about to experience was one of the most stressful spacewalks in history, so it is perhaps no surprise that three years later he is still telling the remarkable tale.
The perfect start to a spacewalk
Although what was to come would send chills down the spine of even the most practised astronaut, the spacewalk began extremely smoothly.
We were 40 minutes ahead of the timeline, which is always a very good fuzzy warm feeling.
“For EVA-23 I was the lead astronaut; I went out first, and it started really well in a very standard way,” explained Parmitano, in a talk at the ESA conference Space for Inspiration.
“We had suited up, depressurised, went outside and started working, and by the time we’d finished our first task everything was perfect. We were 40 minutes ahead of the timeline, which is always a very good fuzzy warm feeling.”
A watery arrival
Parmitano’s first task involved working in a very cramped space between several of the ISS’modules, so initially much of his attention was focused on “trying to figure out how possible it is to work in such an environment”.
However, as he went to extract himself from this space, he felt a rather strange presence in his helmet.
“As I was pulling out I felt something on the back of my head,” he said. “And because I have a lot of skin on my head, I could feel right away that on the back of my head I had some water.”
The next step was to make a call to ground control, which went as follows:
Parmitano: FYI, I feel a lot of water on the back of my head, but I don’t think it’s from my bag.
Houston: Are you sweating, are you working hard?
Parmitano: Um, I am sweating, but it feels like a lot of water.
At this stage, however, no one was particularly concerned, Parmitano included.
“What’s happening is I’m calling FYI – for your information – I feel a lot of water in my helmet. My drinking bag is completely full – I want to keep going because I don’t feel any danger,” he explained.
“I think it’s going to be a nuisance; I have a feeling it’s going to get in my ear, just like when you’re in the shower and you get water inside your ear and you can only hear from one side, but I’m not concerned at all.
“I’m a little bit annoyed and I wonder: are they going to cut my EVA short? Because I really want to finish my job.”
At this stage the atmosphere around the issue is extremely casual. Parmitano isn’t concerned; he just wants to get on with his spacewalk, and ground control is more puzzled than anything else. So for the next few minutes, the focus is on trying to work out where the water might be coming from.
The first possibility was Parmitano’s water bag; a 750ml bag of water that is integrated into the spacesuit to keep astronauts hydrated for the duration of the spacewalk. However, Parmitano is fairly adamant that this isn’t the cause, which leads ground control to wonder whether it is just sweat.
“He asked me: ‘are you sweating?’ Well, right now I’m in the sun so it’s about 150° outside. So yes, I’m sweating, a little bit, but this feels like a lot of water.”
Rising panic in space
After about 20 minutes of speculation between Parmitano and ground control, he is joined by the other astronaut on the EVA, NASA’s Chris Cassidy, who is able to take the first proper look at the water in Parmitano’s helmet.
What he sees is something akin to a watery snood; the liquid has covered the top of Parmitano’s head and is now creeping down his forehead – not a sight you’d expect to see if this was just caused by sweat.
“We start wondering: okay, this is definitely not sweat, how much can I be sweating? I mean, I’m human after all!” Parmitano laughed.
Shortly after, however, the water starts to creep into the earphones and mic of his comms system, causing mission control’s puzzlement to transform into mild panic.
“All this time in the mission control centre people are going berserk. Because where is this water coming from?” he said.
“We had no provisions to tell us what was happening. We had never seen this before – we had never even imagined this happening before, so we just don’t know.”
At this stage it was pretty clear that despite no one knowing where it was coming from, the water was increasing, which led mission control to take the sensible decision to terminate the mission.
“Terminate means you’re cool, there’s no danger,” explained Parmitano. “You’re going to go back inside at your own pace, we’re going to clean up the work site that we have been working on so that it’s not left hanging, and we’re going to talk about this later.”
Six minutes of hell
Up until this point, Cassidy and Parmitano had been connected by a long tether as an additional safety measure. However, as both of them have been working on different parts of the ISS, the wire was now wrapped around different parts of the space station, forcing them to separate so they could both safely get back inside.
“We never like to do that, we like to be in sight – we are buddies – but we just had to say ‘goodbye for now, I’ll see you back at the entrance’,” explained Parmitano.
In a matter of seconds Parmitano went from being mildly annoyed and about to head back, to being unable to see or hear while on his own in the vacuum of space
“And it’s here from this minute until maybe six, seven minutes later – but it felt like a lifetime – where everything happens at the same time, just like all the best stories.”
Parmitano’s immediate task was to make it back to the entrance of the ISS while avoiding the various sensors, experiments and containers that are fixed to the outside of the space station, and which could either be damaged or cause damage to Parmitano if he came into contact with them.
In order to move himself onto the correct path back to the entrance, he had to turn himself upside down – ordinarily a pretty standard procedure in a spacewalk. However, when he did this two things happened.
First, by sheer coincidence the Sun happened to set at the same time he was turning. And when the Sun sets in space, it’s a very speedy affair.
“It’s not one of our beautiful sunsets on Earth the last for a minute; it’s like shutting down the lights,” explained Parmitano. “One moment you have light and heat, the next second you have complete darkness and you don’t see anything except for what’s right in front of you through the lights.”
The second occurrence was perhaps a bit more predictable; as he turned, the water spread further over his face.
“When I turned around the water crawled over my eyes, covered my eyes, went over my nose and, because of this wonderful effect called capillarity, went inside my nose and covered my ears,” he said.
“I have no hair. There’s no hair to mop the water – so it just kept crawling. And it almost looks like a gelatinous substance – it looks like Jell-O slowly creeping.
“And you cannot wick it off; it does not fly away if you shake your head. Trust me, I did it! It just sticks to your skin, of which I have a lot.”
As a result, in a matter of seconds Parmitano went from being mildly annoyed and about to head back, to being unable to see or hear while on his own in the vacuum of space.
“In one second – in one split second – I was isolated outside, in the dark, in the cold with no visibility. I couldn’t hear anything, I couldn’t say anything, because I asked for help; I checked with ground, I checked with Chris, nobody could hear me.”
Back to safety
Alone and completely isolated, Parmitano was now faced with a choice: remain where he was and hope that Cassidy found him before the water engulfed his mouth and cut off his breathing, or attempt to make it back to the ISS using only his sense of touch, impeded by thick gloves.
“My instinct told me it was better for me to try and save myself, and I started crawling back using a single indication of my direction, which was my second tether pulling me slightly, with about half a pound of tension, pulling me in one direction.”
Still unable to see or hear, he began to slowly move back in the direction his tether suggested the ISS’ entrance was.
“That’s why the six minutes felt so long; I had to check every motion I did before I could move, with water in my eyes, in my nose and in my ears, talking constantly, hoping that the ground were receiving signals. However, they were not receiving them.”
Parmitano doesn’t have the clearest memory of his arrival back at the airlock, but the audio recording suggests that he was extremely shaken by the experience.
“When I heard this radio call six months after I had landed, for the first time, I had a chill going down my spine because there is one thing I say that is very out of character,” he explained.
“They asked me what‘s your status and I say ‘I’m at the airlock, I’ve opened the cover, I’m going back inside’ and then there is a break and I say ‘there is a lot of water’. And for me to say something like that is very out of character; I didn’t remember this at all.”
However, although he had arrived safely, he still had to endure the 20-minute repressurisation process.
“I was incredibly uncomfortable, I remember that, all the way through repressurisation, for several reasons,” he explained.
“Imagine having your face just immersed in water for about 20 minutes from beginning to end, and you cannot hear and they’re repressurising, just like when you’re on an aeroplane coming down and your ears start feeling the pressure.
“I could not resolve that, I could not do the plugging manoeuvre, so there was nothing I could do except endure this very painful pressure in my ears. They tried to call me; they called me several times, but I couldn’t hear anything and they couldn’t hear me.
“I was constantly talking, actually trying to slow down the repressurisation, but they couldn’t hear me.”
Once the repressurisation process had finished, Parmitano’s crewmates were tasked with helping him out of his suit, at which point the true severity of the situation was finally revealed.
“The moment when they removed my helmet, that’s when we found out that about 1.5l of water had collected inside the helmet. Now the helmet is pretty small, so a litre and a half of water is quite a bit – it really felt like I was a goldfish in a fishbowl, on the wrong side.”
Parmitano largely credits his survival to the quality of training he and his crewmates received before they embarked on the mission, although at the time this particular scenario was never practised for.
An extensive NASA inquiry into the event also criticised the early focus on his water bag, as well as the initially lax attitude towards the presence of water in the helmet. Perhaps more importantly, it also determined exactly what had caused the mysteriously leak.
A component within Parmitano’s primary life-support system, known as a Fan Pump Separator, had failed. Ordinarily this component is responsible not only for circulating air and oxygen through the system responsible for separating and storing exhaled CO2, but also for transporting the coolant that is used to call the air the astronaut breathes.
In essence, this separator was pumping coolant-tainted water directly into his helmet – a scenario engineers had no idea could occur, as it had never happened during tests on the ground in 1G conditions.