Early Friday, NASA astronauts Jessica Meir and Christina Koch will conduct the first all-female spacewalk outside of the International Space Station. The spacewalk will begin at 7:50 a.m. ET and last for about five or six hours.
In order to tell the astronauts apart, Koch's helmet camera views will bear the number 18 and Meir's will be number 11. Koch's spacesuit also has red stripes on it.
This will be the fourth spacewalk for Koch and the first for Meir.
The first woman to conduct a spacewalk was Russian cosmonaut Svetlana Savitskaya in 1984, followed closely by NASA astronaut Kathy Sullivan. An additional 12 US women have conducted 40 spacewalks over the past 35 years. Koch and Meir will be 13th and 14th, respectively.
Koch and Meir spoke about women working in human spaceflight during a recent news conference.
"I think it's important because of the historical nature of what we're doing and that in the past, women haven't always been at the table," Koch said. "It's wonderful to be contributing to human spaceflight at a time when all contributions are being accepted, when everyone has a role and that can lead, in turn, to increased chance for success.
"There are a lot of people that derive motivation from inspiring stories from people that look like them and I think it's an important aspect of the story to tell," Koch said.
"What we're doing now shows all the work that went in for the decades prior, all of the women that worked to get us where we are today," Meir added. "I think the nice thing for us is we don't even really think about it on a daily basis, it's just normal. We're part of the team, we're doing this work as an efficient team working together with everybody else, so it's really nice to see how far that we've come."
Meir tweeted about preparing for the walk.
Gearing up for Friday’s spacewalk to help the ground teams repair one of the battery channels with @Astro_Christina.
. . . first spacesuit selfie, check!✔️
— Jessica Meir (@Astro_Jessica) October 16, 2019
"Gearing up for Friday's spacewalk to help the ground teams repair one of the battery channels with @Astro_Christina. . . . first spacesuit selfie, check! Photos will be much more spectacular once we pass through the hatch. Be sure to watch live: https://nasa.gov/live"
Koch and Meir will be replacing a faulty battery charge/discharge unit that failed to activate after a spacewalk October 11, according to the agency. Because the unit is faltering, it's keeping newly installed batteries from providing an increase in power to the station.
The space station is powered by solar arrays and four sets of batteries. Luckily, the faulty unit hasn't changed anything for the astronauts or experiments on board. The unit regulates the charge in the batteries from the solar arrays as the station orbits at night around the Earth.
Once the unit is replaced, postponed spacewalks to replace the batteries can be rescheduled.
Although floating in space looks easy, astronauts say that spacewalks are one of the most physically challenging things they can do, according to NASA.
This is the second attempt at an all-female spacewalk after the first was scrapped in March.
For the intended spacewalk in March, Koch was going to be paired with astronaut Anne McClain, who has since returned to Earth. In March, NASA cited spacesuit availability as the reason for scrapping the walk. McClain herself made the decision and the teams supported her, Koch said.
"We do our best to anticipate the spacesuit sizes that each astronaut will need, based on the spacesuit size they wore in training on the ground, and in some cases (including Anne McClain's) astronauts train in multiple sizes," Brandi Dean with NASA's public affairs office told CNN in March.
"However, individuals' sizing needs may change when they are on orbit, in response to the changes living in microgravity can bring about in a body," Dean said. "In addition, no one training environment can fully simulate performing a spacewalk in microgravity, and an individual may find that their sizing preferences change in space."
Koch conducted the spacewalk with fellow astronaut Nick Hague instead of McClain.
When asked about spacesuit availability this time around, Koch said there are currently two medium spacesuits on board. After the first all-female plan was shifted, Koch configured the second spacesuit herself using what was available on board.
She and Meir have trained in medium-sized suits for the past six years.
Koch arrived on the International Space Station on March 14 for her first spaceflight mission. She is set to remain on the station until February 2020, which will make her time on the station the longest single spaceflight by a woman.
Koch's mission will surpass that of Peggy Whitson, who spent 288 consecutive days in space, and end up just shy of the longest single spaceflight by a NASA astronaut: 340 days, set by Scott Kelly.
Meir arrived on the space station for her first mission at the beginning of October. She shared an image of her hugging Koch after arriving.
"This is how it feels when in addition to your childhood dream being fulfilled by arriving to @Space_Station, you're greeted by your Astro-brothers and sisters on the other side of the hatch," Meir said in her tweet.
She and Koch have trained together for the past six years because they're members of the same astronaut class. Meir is set to spend more than six months on board the station.
The upcoming spacewalks will help replace solar array batteries and upgrade them to lithium-ion batteries, as well as refurbish the Alpha Magnetic Spectrometer, a scientific instrument "that explores the fundamental nature of the universe," according to NASA.