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Spacewalk Reassignments: What’s the Deal?

March 28, 2019

On Friday, March 29, Christina Koch and Anne McClain were scheduled to perform a spacewalk together to upgrade the power systems of the International Space Station. It would have been the first all-female spacewalk in human history. While disappointing to many people, after the last spacewalk was completed March 22, NASA changed the assignments to protect the safety of the crew and the timing of the mission. Now, Christina Koch and Nick Hague will be performing this upcoming spacewalk, leaving lots of people are wondering: What’s the deal?

1. Why did the availability of spacesuit sizes affect the schedule?

Spacesuits are not “one size fits all.” We do our best to anticipate the spacesuit sizes each astronaut will need, based on the spacesuit size they wore in training on the ground, and in some cases astronauts train in multiple sizes.

McClain trained in both a medium and a large on Earth. However, living in microgravity can change the size of your body! In fact, Anne McClain has grown two inches since she launched to the Space Station.

McClain realized that the medium she wore during the March 22 spacewalk was a better fit for her in space. She had planned to wear a large during the March 29 spacewalk.

In a tweet, McClain explained: “This decision was based on my recommendation. Leaders must make tough calls, and I am fortunate to work with a team who trusts my judgement. We must never accept a risk that can instead be mitigated. Safety of the crew and execution of the mission come first.”

To provide each astronaut the best fitting spacesuit during their spacewalks, Koch will wear the medium torso on March 29, and McClain will wear it again on April 8.


2. Why is spacesuit sizing so important?

The spacesuit is a mini spaceship that keeps our astronauts alive while they are spacewalking!

Astronauts train several hours on Earth in the Neutral Buoyancy Lab for every hour they spend spacewalking. Spacewalks are the most physically demanding thing we ask astronauts to do, which is why an optimally fitted spacesuit is important to completing the assigned tasks and overall mission!


3. How come you don’t have enough spacesuits in the right size?

McClain NBL
Astronaut Anne McClain gets assistance putting on her spacesuit during her ASCAN EVA Skills 3 Training.
Credits: NASA / Lauren Harnett

We do have enough torsos. The spacesuit takes into account more than 80 different body measurements to be configured for each astronaut. The suit has three sizes of upper torso, eight sizes of adjustable elbows, over 65 sizes of gloves, two sizes of adjustable waists, five sizes of adjustable knees and a vast array of padding options for almost every part of the body.

 In space, we have two medium hard upper torsos, two larges and two extra larges; however, one of the mediums and one of the extra larges are spares that would require 12 hours of crew time for configuration.

Configuring the spare medium is a very methodical and meticulous process to ensure the intricate life support system – including the controls, seals, and hoses for the oxygen, water, and power as well as the pressure garment components – are reassembled correctly with no chance of leaks. 

Nothing is more important than the safety of our crew!

12 hours might not seem like a long time, but the space station is on a very busy operational schedule. An astronaut's life in space is scheduled for activities in five minute increments. Their time is scheduled to conduct science experiments, maintain their spaceship and stay healthy (they exercise two hours a day to keep their bones and muscles strong!).

The teams don’t want to delay this spacewalk because two resupply spacecraft – Northrop Grumman Cygnus and SpaceX cargo Dragon – are scheduled to launch to the space station in the second half of April. That will keep the crew very busy for a while! 


4. Why has there not already been an all-female spacewalk?

NASA does not make assignments based on gender.

The first female space shuttle commander, the first female space station commander and the first female spacewalker were all chosen because they the right individuals for the job, not because they were women. It is not unusual to change spacewalk assignments as lessons are learned during operations in space.

McClain became the 13th female spacewalker on March 22, and Koch will be the 14th this Friday – both coincidentally during Women’s History Month! Women also are filling two key roles in Mission Control: Mary Lawrence as the lead flight director and Jaclyn Kagey as the lead spacewalk officer.


5. When will the all-female spacewalk happen?

An all-female spacewalk is inevitable! As the percentage of women who have become astronauts increases, we look forward to celebrating the first spacewalk performed by two women! McClain, Koch (and Hague!) are all part of the first astronaut class that was 50 percent women, and five of the 11 members of the 2017 astronaut candidate class are also women.

You can watch the upcoming spacewalk on March 29 at 6:30 ET, which is one in a series to upgrade the station’s power technology with new batteries that store power from the solar arrays for the station to use when it is in orbital night.

Thalia Patrinos