National Geographic

Top 5 Space Station Repair Spacewalk Dangers

This digital animation shows NASA astronauts performing spacewalks to repair a faulty cooling pump on the outside of the International Space Station. Credit: NASA TV

Tensions are high as the astronauts aboard the International Space Station ready themselves to conduct a series of emergency spacewalks that start this weekend, ones intended to correct a critical cooling system failure.


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

  1. Suit punctures
    Micro-meteors or tiny shards of metal—even ones 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 a spacesuit too quickly and then heads outside the station, they may get the bends, or decompression sickness. 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. Without it, rapid change in air pressure would cause nitrogen gas bubbles to expand in their blood vessels, causing severe pain, cramping, and even paralysis or death.
  3. Exhaustion and loss of consciousness
    Despite having their own heating/cooling systems, spacesuits can get really hot, especially when astronauts are conducting physically demanding walks that go on for many hours. Ground controllers therefore monitor the astronauts’ vital signs to make sure they are 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 after leaving the airlock. Spacesuits are directly tethered to the ISS. However, if a spacesuit does somehow detach, there’s a way back in—NASA spacesuits all have mini-jet packs that allow the spacewalker to float back to the station.
  5. Leaking water in spacesuit
    This frightening and unprecedented scenario played out during an aborted spacewalk in June, when Italian astronaut Luca Parmitano’s helmet unexpectedly began filling with water. 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. Once fellow crewmates removed his helmet, they noticed that it contained quite a bit of water—as much as two cups (half a liter). At the time Pamitano wrote about the incident on his ESA blog and shared his idea for one scary solution that thankfully he didn’t have to try. “The only idea I can think of is to open the safety valve by my left ear: if I create controlled depressurisation, I should manage to let out some of the water, at least until it freezes through sublimation, which would stop the flow. But making a ‘hole’ in my spacesuit really would be a last resort.” Repairs have been conducted on the suit, and NASA plans on using it during this weekend’s spacewalks, according to the space agency.

Holiday Spacewalk Schedule

NASA astronauts Rick Mastracchio and Mike Hopkins will be suiting up and stepping outside to conduct the repairs, while  Japanese astronaut Koichi Wakata will act as crane operator, at the helm of the Canadarm2 robotic arm during the spacewalk.

NASA astronaut Rick Mastracchio checks U.S. spacesuits in the Quest airlock. Image Credit: NASA TV
Image Credit: NASA TV

The first spacewalk is scheduled for Saturday at 7:10 a.m. EST when the spacewalkers will set up the worksite on the S1 truss. First they will disconnect cables to the faulty pump module and install jumper cables to act as temporary replacements. Mastracchio and Hopkins will then open up insulation covering the pump module.

A second spacewalk will continue the work on Monday, also scheduled to start at 7:10 a.m. EST, when Mastracchio and Hopkins will remove the dead pump and replace it with a spare module. Meanwhile, Wakata will gingerly choreograph movements of the Canadarm 2 with Mastracchio riding on its end.

If necessary, a third spacewalk on Christmas Day will be done to finish the installation of the spare pump module. The last time a spacewalk took place on Christmas Day was in 1974 during the Skylab 4 mission. NASA astronauts Gerald Carr and William Pogue stepped outside the Skylab space station to retrieve film from a telescope and photograph Comet Kohoutek.


You can watch all the action live on NASA Television, where coverage of the spacewalks begins on Saturday at 6:10 a.m. EST.





  1. Dwayne LaGrou
    Lapeer, MI
    December 20, 2013, 11:47 pm

    I was just thinking about the water in the helmet problem. Is it possible to place a sponge like material that will absorb water and wick it away without expanding inside the helmet or as a wrap around the inside of the helmet to help avoid a problem like what happened and to also help control excessive sweating? Just a thought, sometimes its the simple solutions that work best.
    Thanks, DL