Last July, Italian astronaut Luca Parmitano and his American partner Christopher Cassidy started what was supposed to be a six-hour repair mission on the International Space Station. However, only an hour into the repair, water began to enter Parmitano’s helmet and threatened to drown him, and a space cable became Parmitano’s only lifeline.

“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,” Parmitano recounts his thoughts in his blog post. “To make matters worse, I realise that I can’t even understand which direction I should head in to get back to the airlock.”

Attempts to call out to Cassidy and mission control proved futile. He was thinking of ways to rid the water—including a “last-resort” idea of opening the safety valve—when he thought of the cable.

“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.”

Parmitano tugged on his safety cable and raced against the rising water back to the airlock. NASA called off the spacewalk, and Cassidy soon joined Parmitano so they could enter the space station. First, they needed to repressurize themselves, and Parminato knew he might lose consciousness if he had to remove the helmet beforehand. “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.

This was Parminato’s second spacewalk; he had become the first Italian with his first spacewalk after coming to the space station in May. NASA traced the problem to his spacesuit backpack, which has life-support equipment including coolant water that may have leaked into his ventilation system through a connector between the spacesuit and helmet, according to a video from Cassidy. The precise reason is still unknown, and until they find the answer NASA has suspended all US spacewalks.

Parmitano’s conclusion in his blog post offers a reminder about space exploration: “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.”