What started off as a fairly routine spacewalk for the International Space Station last month quickly turned into something much scarier when water started leaking into an astronaut's helmet. Now, for the first time, we're hearing about the drowning scare in the astronaut's own words.

Flight engineer Luca Parmitano (right) was working to repair some cables on the ISS's exterior during a spacewalk with American astronaut Chris Cassidy on July 16 when he started to feel condensation pool in the rear of his helmet. My head is really wet and I have a feeling it's increasing," Parmitano told Johnson Space Center in Houston about an hour into the mission. Last night, on his personal blog, Parmitano explained that he was in one of the most difficult positions outside the space 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" -- when the unthinkable started to happen: The sensation of water pooling around the back of his neck Eventually, the liquid started interrupting the Italian astronaut's ability to see, speak and hear:

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. 

Houston did, in fact, decide to terminate the mission early: Parmitano and Cassidy were scheduled to perform maintenance for six or seven hours -- the mission lasted one hour, 32 minutes in the end. What follows is one of the most terrifying, unimaginable passages you may have ever read. Imagine being in a spacesuit, a fishbowl helmet literally keeping you alive and filling with water, losing your ability to see or communicate or breathe, and having to perform a series of space gymnastics with your life on the line. A warning: You may need a paper bag handy to make it through this: 

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.

Thankfully, Parmitano was able to find his way back into the airlock. He realized -- once inside the ISS and fellow astronauts Karen Nyberg, Pavel Vinogradov and Fyodor Yurchikhin worked to dry him off -- that they had not heard him while he was making his way towards the safety hatch, despite his attempts to communicate during the crisis. The first indication Parmitano was safe came when he and Cassidy were in the airlock, waiting for permission to reenter the ISS:

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! 

This is where we should probably note that Parminto was on his second spacewalk, ever. The crisis reminded more than one Atlantic Wire staff member of something straight out of Gravity -- the upcoming space/horror movie from Alfonso Cuarón

Cassidy, Parmitano's partner on the spacewalk, already identified a malfunction in the suit’s cooling system as the source of the leak. What Parmitano experienced is a rare but not unprecedented problem. That said, it's enough to keep some of us firmly planted on the ground and thankful that we have people brave enough to live and work in the Earth's orbit.