The Four Biggest Risks for Conducting a Spacewalk

Astronaut Luca Parmitano just before aborting the spacewalk. Video still from NASA TV via AFP/Getty Images
Astronaut Luca Parmitano just before aborting the spacewalk. Video still from NASA TV via AFP/Getty Images

An hour into this morning’s scheduled six-hour-long spacewalk to do maintenance work on the International Space Station, astronaut Luca Parmitano’s helmet began inexplicably filling with water.

At first Parmitano, a major in the Italian Air Force, notified ground controllers that he was feeling something unusual on the back of his head.

“My head is really wet and I have a feeling it’s increasing,” Parmitano told  flight controllers on the ground in Houston.

But as the water began to accumulate further, it clearly became more than just a nuisance.

“It’s too much … Now it’s in my eyes,” he relayed.

Ground controllers became concerned that Parmitano could choke on the floating blobs of water, so the spacewalk was immediately halted. Parmitano was then assisted back to the airlock by American Christopher Cassidy, a veteran spacewalker. Once fellow crewmates removed his helmet, they noticed that it contained quite a bit of water — as much as half a liter or 2 cups.

As of Tuesday, NASA is still trying to figure out the exact source of the water.

Astronauts like Parmitano constantly train for various emergency scenarios that may crop up during walks outside the International Space Station. But there are risks involved in the activity, including:

  1. Suit leaks
    Micro-meteors or tiny shards of metal  – even those the size of a grain of sand – could cause a puncture and create a catastrophic leak in the spacesuit. Spacewalkers conduct regular examinations of their gloves and suit for leaks while on spacewalks.
  2. Decompression sickness or ‘the bends’
    If an astronaut puts on his/her spacesuit too quickly and then heads outside the station, there’s reason for alarm. Because of the rapid change in air pressure, nitrogen gas bubbles would expand in their blood vessels, causing severe pain, cramping and even paralysis or death. To prevent decompression sickness astronauts undergo a denitrogenation process prior to all spacewalks because the ambient pressure in their spacesuits is much lower than inside the space station.
  3. Exhaustion-loss of consciousness
    Despite having its own heating/cooling system, spacesuits can get really hot, especially when astronauts are conducting physically demanding walks that go on for many hours. Ground controllers therefore monitor astronaut vital signs making sure they breathing regularly and don’t overheat and pass out.
  4. Accidental detachment from spaceship
    Astronauts go through countless hours of training for spacewalks to familiarize themselves with the exact route they will take once leaving the airlock. Spacesuits are directly tethered to the ISS. However if a spacesuit would detach somehow, there’s a way back in: NASA spacesuits all have mini-jet packs allowing the spacewalker to float back to the station.


Check out more cool NASA facts on spacesuits and spacewalks.


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Changing Planet

Meet the Author
Andrew Fazekas, aka The Night Sky Guy, is a science writer, broadcaster, and lecturer who loves to share his passion for the wonders of the universe through all media. He is a regular contributor to National Geographic News and is the national cosmic correspondent for Canada’s Weather Network TV channel, space columnist for CBC Radio network, and a consultant for the Canadian Space Agency. As a member of the Royal Astronomical Society of Canada, Andrew has been observing the heavens from Montreal for over a quarter century and has never met a clear night sky he didn’t like.