Christina Koch and Jessica Meir will become the first to partake in history’s only all-women spacewalk aboard the International Space Station (ISS) on October 21.

The originally planned first all-female spacewalk was canceled last March, when NASA announced it only had one suitably fitting spacesuit for the two women aboard the International Space Station. Instead, both women took part in two separate co-ed spacewalks.

The spacesuit that will be worn during the spacewalk is the Extravehicular Mobility Unit (EMU), a specially designed “personal spaceship” of a suit that keeps the astronauts safe in the high-pressure vacuum of space. The spacesuit contains breathing and temperature controls, communication systems, battery power, and offers protection from radiation and space debris. One part of the suit, the hard upper torso (HUT), created the hiccup in the last all-female spacewalk attempt. Both women best fit a medium-sized HUT, but the ISS only had one available.  

“Due to a number of factors, ranging from safety to fit and performance, a crewmember may decide in orbit that their size preferences have changed. This is not uncommon, as astronauts’ bodies change on orbit and ground-based training can be different than performing spacewalks in the microgravity environment outside the space station,” wrote NASA in a statement. They added that “when that occurs, the teams on the ground determine what course of action will best accommodate both the astronauts’ preferences and the demands of the space station’s schedule.”

The spacewalk is one of the most dangerous tasks that an astronaut will take part in during their time aboard the ISS. Each typically lasts around 6.5 hours while the astronaut remains tethered to their spacecraft to keep from floating away. Just like in the movies, astronauts wear small backpack-sized units complete with jet thrusters operated by a joystick to help them move around safely. 

The October 21 event is one of 10 spacewalks outside of the ISS that are scheduled to occur over the next few weeks, the first five of which are meant to replace outdated nickel-hydrogen batteries on the space station’s truss and the following five to repair the Alpha Magnetic Spectrometer (AMS). The AMS has been attached to the ISS since May 2011 and is used to detect dark matter.  

The next nine spacewalks will be live-streamed on NASA television

Related posts