US astronauts Christina Koch and Jessica Meir on Friday became the first all-female pairing to carry out a spacewalk - a historic milestone as NASA prepares to send the first woman to the Moon. The mission was originally planned for earlier this year but had to be aborted due to a lack of properly fitting spacesuits, leading to allegations of sexism.

"Christina, you may egress the airlock," spacecraft communicator Stephanie Wilson said as the pair set out to replace a power controller on the International Space Station at 1138 GMT. They began their mission with standard safety checks on their suits and tethers, before making their way to the repair site on the station's port side, as the sunlit Earth came into view.

In a call to reporters a few minutes earlier, NASA administrator Jim Bridenstine emphasized the symbolic significance of the day. "We want to make sure that space is available to all people, and this is another milestone in that evolution," he said.

"I have an 11-year-old daughter, I want her to see herself as having all the same opportunities that I found myself as having when I was growing up."

The first all-female spacewalk was supposed to take place in March but was canceled because the space agency had only one medium-sized suit. A male-female team performed the required task at a later date. Traditionally male-dominated NASA's failure to be adequately prepared was denounced in some quarters as evidence of implicit sexism.

When the women astronauts had been outside the space station for about five hours, President Donald Trump reached them in a video call and told them they had made history.

Copyright Agence France-Presse, 2019