My eyes are closed as I listen to Chris counting down the atmospheric pressure inside the airlock – it’s close to zero now. But I’m not tired – quite the reverse! I feel fully charged, as if electricity and not blood were running through my veins. I just want to make sure I experience and remember everything. I’m mentally preparing myself to open the door because I will be the first to exit the Station this time round. Maybe it’s just as well that it’s night time: at least there won’t be anything to distract me.

When I read 0.5 psi, it’s time to turn the handle and pull up the hatch. It is pitch black outside, not the colour black but rather a complete absence of light. I drink in the sight as I lean out to attach our safety cables. I feel completely at ease as I twist my body to let Chris go by. In a matter of seconds, we finish checking each other and we separate. Even though we are both heading to more or less the same part of the International Space Station, our routes are completely different, set out by the choreography we have studied meticulously. My route is direct, towards the back of the Station, while Chris has to go towards the front first in order to wind his cable around Z1, the central truss structure above Node 1. At that moment, none of us in orbit or on Earth could have imagined just how much this decision would influence the events of the day.

I pay careful attention to every move as I make my way towards the protective bag that we left outside the week before. I don’t want to make the mistake of feeling so much at ease as to be relaxed. Inside the bag I find the cables that form part of what will perhaps be my most difficult task of the day. I have to connect them to the Station’s external sockets while at the same time securing them to the surface of the station with small metal wires. Both operations involve me using my fingers a lot, and I know from experience that this will be really tiring because of the pressurised gloves.

Chris partially connected the first cable last week, so I get hold of the part that is still unattached and I guide it carefully towards the socket. After a little initial difficulty, I inform Houston that I have completed the task and I’m ready for the second cable. After getting hold of the next cable, I move into what I think is the most difficult position to work from on the whole Station: I’m literally wedged between three different modules, with my visor and my PLSS (my ‘backpack’) just a few centimetres from the external walls of Node 3, Node 1 and the Lab. Very patiently, with considerable effort I manage to fasten one end of the second cable to the socket. Then, moving blindly backwards, I free myself from the awkward position I’ve had to work in. On the ground, Shane tells me that I’m almost 40 minutes ahead of schedule, and Chris is also running ahead on his tasks.

At this exact moment, just as I’m thinking about how to uncoil the cable neatly (it is moving around like a thing possessed in the weightlessness), I ‘feel’ that something is wrong. The unexpected sensation of water at the back of my neck surprises me – and I’m in a place where I’d rather not be surprised. I move my head from side to side, confirming my first impression, and with superhuman effort I force myself to inform Houston of what I can feel, knowing that it could signal the end of this EVA. On the ground, Shane confirms they have received my message and he asks me to await instructions. Chris, who has just finished, is still nearby and he moves towards me to see if he can see anything and identify the source of the water in my helmet.

At first, we’re both convinced that it must be drinking water from my flask that has leaked out through the straw, or else it’s sweat. But I think the liquid is too cold to be sweat, and more importantly, I can feel it increasing. I can’t see any liquid coming out of the drinking water valve either. When I inform Chris and Shane of this, we immediately receive the order to ‘terminate’ the sortie. The other possibility, to ‘abort’, is used for more serious problems. I’m instructed to go back to the airlock. Together we decide that Chris should secure all the elements that are outside before he retraces his steps to the airlock, i.e. he will first move to the front of the Station. And so we separate.

As I move back along my route towards the airlock, I become more and more certain that the water is increasing. I feel it covering the sponge on my earphones and I wonder whether I’ll lose audio contact. The water has also almost completely covered the front of my visor, sticking to it and obscuring my vision. I realise that to get over one of the antennae on my route I will have to move my body into a vertical position, also in order for my safety cable to rewind normally. At that moment, as I turn ‘upside-down’, two things happen: the Sun sets, and my ability to see – already compromised by the water – completely vanishes, making my eyes useless; but worse than that, the water covers my nose – a really awful sensation that I make worse by my vain attempts to move the water by shaking my head. By now, the upper part of the helmet is full of water and I can’t even be sure that the next time I breathe I will fill my lungs with air and not liquid. To make matters worse, I realise that I can’t even understand which direction I should head in to get back to the airlock. I can’t see more than a few centimetres in front of me, not even enough to make out the handles we use to move around the Station.

I try to contact Chris and Shane: I listen as they talk to each other, but their voices are very faint now: I can hardly hear them and they can’t hear me. I’m alone. I frantically think of a plan. It’s vital that I get inside as quickly as possible. I know that if I stay where I am, Chris will come and get me, but how much time do I have? It’s impossible to know. Then I remember my safety cable. Its cable recoil mechanism has a force of around 3lb that will ‘pull’ me towards the left. It’s not much, but it’s the best idea I have: to follow the cable to the airlock. I force myself to stay calm and, patiently locating the handles by touch, I start to move, all the while thinking about how to eliminate the water if it were to reach my mouth. The only idea I can think of is to open the safety valve by my left ear: if I create controlled depressurisation, I should manage to let out some of the water, at least until it freezes through sublimation, which would stop the flow. But making a ‘hole’ in my spacesuit really would be a last resort.

I move for what seems like an eternity (but I know it’s just a few minutes). Finally, with a huge sense of relief, I peer through the curtain of water before my eyes and make out the thermal cover of the airlock: just a little further, and I’ll be safe. One of the last instructions I received was to go back inside immediately, without waiting for Chris. According to protocol, I should have entered the airlock last, because I was first to leave. But neither Chris nor I have any problem in changing the order in which we re-enter. Moving with my eyes closed, I manage to get inside and position myself to wait for Chris’ return. I sense movement behind me; Chris enters the airlock and judging from the vibrations, I know that he’s closing the hatch. At that moment, communication passes to Karen and for some reason, I’m able to hear her fairly well. But I realise that she can’t hear me because she repeats my instructions even though I’ve already replied. I follow Karen’s instructions as best I can, but when repressurization begins I lose all audio. The water is now inside my ears and I’m completely cut off.

I try to move as little as possible to avoid moving the water inside my helmet. I keep giving information on my health, saying that I’m ok and that repressurization can continue. Now that we are repressurizing, I know that if the water does overwhelm me I can always open the helmet. I’ll probably lose consciousness, but in any case that would be better than drowning inside the helmet. At one point, Chris squeezes my glove with his and I give him the universal ‘ok’ sign with mine. The last time he heard me speak was before entering the airlock!

The minutes of repressurization crawl by and finally, with an unexpected wave of relief, I see the internal door open and the whole team assembled there ready to help. They pull me out and as quickly as possible, Karen unfastens my helmet and carefully lifts it over my head. Fyodor and Pavel immediately pass me a towel and I thank them without hearing their words because my ears and nose will still be full of water for a few minutes more.

Space is a harsh, inhospitable frontier and we are explorers, not colonisers. The skills of our engineers and the technology surrounding us make things appear simple when they are not, and perhaps we forget this sometimes.

Better not to forget.