The first all-female spacewalk is happening today outside the International Space Station. At 7:38 AM ET, astronauts Jessica Meir and Christina Koch exited the airlock, and the walk is scheduled to last for five or six hours. The first spacewalk for Meir and the fourth for Koch, the two astronauts will be replacing the station’s faulty power regulator, which has been in operation since 2000. While it isn’t the first time a woman has participated in a spacewalk, it is the first time a group composed of all women has done so.

“I think it’s important,” Koch said in a news conference, “because of the historical nature of what we’re doing and that in the past, women haven’t always been at the table. 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.”

Meir added, “What we’re doing now shows all the work that went on for the decades prior, all of the women that worked to get us where we are today.”

Originally, the first all-female spacewalk was supposed to take place back in March, but the plan was scrapped due to spacesuit availability issues. Koch had been scheduled to make that initial walk with fellow astronaut Anne McClain, but she has since returned to Earth.

Meir only arrived on the station at the beginning of this month and already has taken a historic step in both her career and for womankind. Upon her arrival, she tweeted about the bond that exists between her and her fellow astronauts.