Astronaut Luca Parmitano had to cut short his spacewalk yesterday, after his helmet flooded with more than a liter of water. How's that happen? Initially, Parmitano suspected a leak in his 32 oz. drink bag, which is fitted into the front of the suit and connects to the helmet via a tube and built-in drinking valve, writes Thomas Jones at Popular Mechanics. But the actual culprit is likely to be the suit's cooling system — a series of water-filled tubes that run all around the astronaut's body.