The astronaut who could have drowned because of a flooded helmet is searching for clues in his spacesuit.
So far, neither Italian astronaut Luca Parmitano nor engineers in Houston have uncovered the cause of Tuesday's close call outside the International Space Station.
The spacewalk was aborted after water leaked into his helmet. The main suspect is the suit's cooling system.
He was unable to speak or hear as the spacewalk came to a hasty close. His eyes were also soaked. NASA says Parmitano could have choked or drowned.
On Wednesday, the next NASA astronaut who's supposed to fly to the space station, Michael Hopkins, said the important thing is that the spacewalkers got back in safely. He's confident NASA will solve the mystery before sending anyone else out the hatch.