International Space Station photo

Two weeks ago, we were impressed by how calm ground control stayed when Italian astronaut Luca Parmitano’s helmet sprung a water leak. Now, after watching this video of astronaut Chris Cassidy explaining how a leaky helmet behaves in space, we’re amazed.

In zero gravity, water doesn’t behave anything like it does on Earth. Parmitano’s helmet sprung a leak in the rear, behind his head, and soaked into his communication gear. But then, thanks to the power of surface tension and a little help from a ventilation fan, something far more horrifying happened.

The water actually formed a shield or bubble and began creeping over the back of his head, wrapping around his face and entering his nose. He couldn’t just poke his head up above the surface here; water wasn’t filling up his helmet so much as it was effectively strangling him. Parmitano easily could have drowned long before the helmet actually got anywhere near “full.”

The various space agencies are still trying to figure out how the leak happened. But one question was definitely solved: we can state with full confidence that astronauts have balls of steel.

[via PBS]