ROUGH CUT (no reporter narration) STORY: Originally intended as the first all-female spacewalk, the second of three scheduled walks around the International Space Station got underway at 07:42 ET on Friday, but with only one female and her male colleague, Nick Hague.
The all-female mission was scrapped by NASA when it was discovered there was only one appropriately sized spacesuit for the women on board.
The pair left the ISS to begin a 6.5 hour spacewalk to upgrade the ISS power storage capacity.
Anne McClain and Christina Koch had been due to step into history books in a spacewalk on Friday, during the final week of Women's History Month.
But McClain gave up her place on the mission to Hague, NASA announced late Monday.
"Mission managers decided to adjust the assignments, due in part to spacesuit availability on the station," NASA said in a statement.
"McClain learned during her first spacewalk that a medium-size hard upper torso - essentially the shirt of the spacesuit - fits her best.
Because only one medium-size torso can be made ready by Friday, March 29, Koch will wear it." Nearly 60 years after the first human blasted off into space, less than 11 percent of the 500 plus people who have travelled to space have been women, and spacewalk teams have either been all-male or male-female.
McClain and Koch were both part of the 2013 NASA class that was 50 percent women.
NASA said the decision to change the plan was made in consultation with McClain after a spacewalk last week.
The NASA announcement was met with disappointment and anger by many following the much-anticipated mission on social media, with some arguing an all-female spacewalk was overdue.
Others said they were sad that a milestone moment on women's space exploration had been deferred, but safety came first.
"I'm super disappointed about the all-woman spacewalk not happening as scheduled this Friday, but I'm also super supportive of astronauts having the authority to say 'I would be safer using a different piece of equipment'," wrote Emily Lakdawalla, a senior editor at the U.S. non-profit The Planetary Society.
"An all-woman spacewalk WILL eventually happen."