just made history as participants in the first-ever all-female spacewalk.

And it’s been a long time coming.

Now you may recall that this historic event was originally scheduled for earlier this year,

with NASA astronauts Anne McClain and Christina Koch.

Yet plans got derailed when a last minute size adjustment required a suit change.

The spacesuits—otherwise known as Extravehicular Mobility Units—are actually made of component parts:

three hard upper torso sizes, four leg sizes, seven lower arm sizes, two waist sizes, and two boot sizes.

With the variety of customizations, they can take up to 12 hours to assemble.

Of the six hard upper torsos on the ISS, one medium and one large were ready for the March 29 spacewalk.

However, it was decided that a medium upper torso actually fit McClain better,

after she’d used one during a previous spacewalk.

And since spacewalking is one of the most dangerous tasks that an astronaut has to complete,

having a suit that fits is critical.

That’s because spacesuits are like mini spacecraft,

providing life support, battery power, communications systems, and radiation protection.

So with only one medium suit prepped for the walk,

NASA was forced to switch McClain with fellow astronaut Nick Hague,

who more comfortably fit the large suit.

The decision caused an uproar, as many believed that NASA didn’t have enough sizes available

for their female astronauts, but the reality is there was another medium suit on board.

Assembling it, however, would have meant missing their mission window.

But this time, the two medium suits were prepped and ready to go, so Koch and Meir were able to make history.

And this spacewalk couldn’t have come at a better time.

NASA is in the process of replacing its original 48 nickel-hydrogen batteries

with 24 lithium-ion power packs, which will better serve the power supply onboard the ISS.

Most critically, following the spacewalk on October 11th, 2019,

a battery power system known as the Battery Charge/Discharge Unit

had failed to connect to the newly installed lithium batteries.

The BCDU’s regulate the amount of charge put into the batteries connected to the station’s solar arrays,

providing an additional power source when the station is in Earth’s shadow.

While this activation failure didn’t endanger the welfare of the ISS crew,

experiments or day-to-day operations, the station was still experiencing a loss of additional power.

So Koch and Meir’s mission was to replace the defective unit with one of the three spares onboard the ISS.

This was Koch’s fourth walk and Meir’s first,

and in the 54 years since the first spacewalk took place,

only a small amount of participants have been women.

But those numbers may soon go up.

Both Koch and Meir’s 2013 astronaut class was 50% female,

and 12 out of 38 of NASA’s active astronauts are women.

And that’s not the only historic aspect here, either.

When Koch returns to Earth next February, she will have spent 328 days in space,

breaking the record for longest spaceflight for a female astronaut of any nationality.

Jessica Meir: “What we’re doing now shows all of the work that went in for the decades prior,

all of the women that worked to get us where we are today.”

For more space videos, check out our Countdown to Launch playlist where we cover rockets,

their payloads, and more, like the Psyche mission, where NASA is sending an orbiter to explore a metal asteroid.

Make sure to subscribe to Seeker and thanks for watching.