Astronaut Chris Cassidy is a space rookie. Yesterday he went on his first extra-vehicular activity in his first space mission, working to replace four aging batteries at the International Space Station. Until something in his suit went very wrong.
His lithium hydroxide CO2 scrubber broke, allowing the lethal gas to build up to dangerous levels. Lithium hydroxide is a corrosive alkali hydroxide, a white hygroscopic crystalline material that is used in filters to purify air. For unknown reason, the filtering mechanism didn't work, and the CO2 wasn't correctly processed. Cassidy didn't notice any apparent effect, but the spacewalk came to a sudden ending after Houston noticed that things weren't right at all inside his suit.
His words after getting into the ISS airlock: "I'm just going to sit here and wait for Dave and enjoy the view."
Balls of titanium, I tell you. [Aviation Week]