The first-ever all-women spacewalk was earlier scheduled for March but was canceled due to lack of appropriately sized spacesuits.
The world's first female spacewalking team is making history high above Earth.
NASA astronauts Christina Koch and Jessica Meir exited the International Space Station on Friday, the first time in a half-century of spacewalking that a woman floated out without a male crewmate. Their job is to fix a broken part of the station's solar power network.
America's first female spacewalker from 35 years ago, Kathy Sullivan, was delighted. She said it's good to finally have enough women in the astronaut corps and trained for spacewalking for this to happen.
"In the past women haven’t always been at the table. It’s wonderful to be contributing to the space program at a time when all contributions are being accepted, when everyone has a role," Koch said earlier when asked about the importance of this spacewalk.
NASA originally wanted to conduct an all-female spacewalk last spring, but did not have enough medium-size suits ready to go.
The duo will replace a failed power controller, also known as a battery charge-discharge unit, NASA said in a statement on Thursday.
First ever all-women spacewalk generated huge amount of public interest although it is the 221st spacewalk performed in support of space station assembly, NASA added.
"The all-women spacewalk wasn't something we purposefully planned, though. It was bound to happen eventually because of the increasing number of female astronauts," NASA stressed.
The spacewalk is expected to take five to six hours, it added.
Space enthusiasts could watch the spacewalk live on NASA TV.
This milestone was scheduled to take place earlier in March which included Koch and fellow astronaut Anne McClain, but it was ultimately cancelled due to the lack of appropriately sized spacesuits.
Friday’s mission will be Koch’s fourth and Meir’s first mission. Both Koch and Meir, selected as astronaut candidates in 2013, are on their first spaceflight, according to NASA.