Spacewalks, also called extravehicular activities (EVAs), are one of the most difficult and dangerous tasks for the astronauts who work on board the International Space Station (ISS).
However, these spacewalks are necessary. EVAs are conducted when:
- equipment needs to be repaired or installed
- intricate manual work that can only be done by human hands is required
Thanks to this extravehicular maintenance, the ISS remains:
- safe for the crew members
- in good condition so that an increasing number of scientific experiments can be conducted
- protected against serious failures and breakdowns affecting essential systems, such as:
- solar energy
- the thermoregulation and survival systems
- the computer networks
- communication and navigation equipment
The stakes are very high: the failure of any one of these components could lead to loss of the ISS!
A very special spacesuit!
During spacewalks, the astronauts can rely on spacesuits equipped with all the necessary survival functions. These suits are the result of more than 50 years of testing, research and development.
These very bulky suits protect the astronauts from the deadly threats posed by the vacuum of space:
Solar and cosmic radiation
Extreme temperature variations
For example, the NASA spacesuit, called the Extravehicular Mobility Unit (EMU), has a total of 14 layers, divided into three parts:
- Three liquid-cooling and ventilation layers, to keep the astronaut cool.
- One pressure bladder layer.
- A nine-layer thermal micrometeoroid garment, to protect the astronaut from micrometeorites and extreme temperature variations.
SAFER: an additional safety system
The EMU is also equipped with SAFER, a propulsion system – a manned manoeuvering unit - which enables the astronauts to return to the ISS in the event of accidental separation.
However, there is little chance of that happening: once outside, the astronauts are securely tethered to the ISS with cables!
A spacewalk usually lasts from five to seven hours.
Canadians step into the vacuum of space
On April 22, 2001, former astronaut Chris Hadfield made history when he became the first Canadian to perform a spacewalk.
Chris Hadfield and American astronaut Scott Parazynski worked for hours to unpack and install Canadarm2 using robotized equipment and other specialized tools.
"It was the most magnificent experience of my life. Alone in a one-person spaceship (my suit), just holding on with my one hand, with the bottomless black universe on my left and the World pouring by in technicolour on my right. I highly recommend it."– Chris Hadfield
Since Chris Hadfield's historic excursion, two other Canadians have walked in space:
Dave Williams holds the Canadian record for time spent on EVAs, accomplished in three spacewalks: 17 hours and 43 minutes!
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