Luca Parmitano speaks during a space suits test, prior to blast off to the International Space Station from the Russian-leased Kazakh Baikonur cosmodrome, May 28, 2013.

Astronaut Describes Nearly Drowning in Space

Two NASA probes are trying to determine why Luca Parmitano's helmet filled with water.

Luca Parmitano speaks during a space suits test, prior to blast off to the International Space Station from the Russian-leased Kazakh Baikonur cosmodrome, May 28, 2013.
By + More

Astronaut Luca Parmitano authored a first-person blog post from the International Space Station Tuesday describing how he nearly drowned during a July 16 space walk.

"The unexpected sensation of water at the back of my neck surprises me," Parmitano writes, walking readers through his terrifying experience outside the station with fellow astronaut Chris Cassidy.

"At first, we're both convinced that it must be drinking water from my flask that has leaked out through the straw, or else it's sweat. But I think the liquid is too cold to be sweat, and more importantly, I can feel it increasing."

Earth-based flight director David Korth decided to terminate the walk, but as the astronauts returned to the station water continued seeping into Parmitano's helmet.

[PHOTOS: Spectacular Snapshots of Space]

"I feel it covering the sponge on my earphones and I wonder whether I'll lose audio contact," Parmitano recalls. "[T]he Sun sets, and my ability to see – already compromised by the water – completely vanishes, making my eyes useless; but worse than that, the water covers my nose – a really awful sensation that I make worse by my vain attempts to move the water by shaking my head. 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."

Before reaching the station's airlock, he considered opening a safety valve on his helmet, "to let out some of the water, at least until it freezes through sublimation, which would stop the flow."

Ultimately, Parmitano reached his destination and after long minutes of repressurizing – during which he considered losing consciousness over drowning by popping off his helmet early – his suit was safely removed.

Parmitano is one of six astronauts currently living at the space station. He's an Italian citizen who works for the European Space Agency. The blog entry was posted to the ESA's website.

[READ: Save Your Miles! Virgin Airlines Offers Top Flier Free Trip to Space]

NASA is reviewing the incident and has yet to draw any conclusions, Houston-based spokesman Josh Byerly told U.S. News.

"There are basically two different investigations going on," he said. One is an "extremely methodical" review of possible engineering flaws in the suit.

"They're working through the different options," Byerly said, "to see if something came loose."

The second investigation, being conducted by a mishap investigation board, is considering big-picture lessons that can be taken from the incident.

There is no deadline for either probe, Byerly said. He declined to discuss preliminary theories about the leak, but Agence France-Presse reports that the suit's cooling system is being scrutinized.

Parmitano's near-death experience was the first known leak of water into a space-traveler's suit, according to the NASA spokesman. So far as he's aware, "the other two space suits on board are fine."

Watch: How water behaves in space:

More News: