Two US astronauts have completed the first ever all-women spacewalk.
Jessica Meir, left, and Christina Koch inside the space station. Photo: Supplied / NASA
The much-anticipated milestone for Nasa was achieved during a relatively routine mission to swap faulty batteries on the station's exterior.
Christina Koch and Jessica Meir, clad in white spacesuits and tethered by cords to the International Space Station some 408km above Earth, stepped into outer space at 11.38GMT to replace a faulty power unit designed to help condition energy stored from the station's solar panels, Nasa announced online as it showed live video of the action.
The mission, which lasted nearly five hours, follows a first attempt at an all-female spacewalk in March. It was called off because one of the astronaut's medium-sized spacesuits was not configured and ready for the journey.
US President Donald Trump congratulated the two women in a video call yesterday, thanking them for their bravery and service.
"This is truly historic," he told the astronauts from a conference room at the White House alongside Vice President Mike Pence, his daughter and presidential adviser Ivanka Trump, and NASA administrator Jim Bridenstine.
Dr Meir said she and Ms Koch could not take too much credit for the achievement, noting "a long line" of other women who paved the way before them.
"There have been many other female spacewalkers before us. This is just the first time that there's been two women outside at the same time," she said. "For us this is really just us doing our jobs."
"This is a first step," Mr Trump told the pair, noting that Nasa was planning to send a woman to the Moon as part of a 2022 mission to build a habitat there.
Ms Koch, an electrical engineer, had already carried out four spacewalks but it was the first for Ms Meir, who has a doctorate in marine biology and who became the 15th woman to walk in space, Nasa said.
Ms Koch is scheduled set to complete the longest single space flight by a woman by remaining in orbit aboard the station until February 2020. She said gender milestones such as the spacewalk are significant.
"There are a lot of people who derive motivation from inspiring stories from people who look like them, and I think that it's an important aspect of the story to tell," she said at a NASA briefing in Houston this month.
Sandra Magnus, a former Nasa astronaut who spent 136 days on the International Space Station, told Reuters she did not want events like the latest spacewalk to become gimmicks.
"We want them to happen because people have the skill sets and they're available to do the job," said Ms Magnus.
"On the other hand, it's important for young women to see women role models doing extraordinary things," she said. "So there's two sides of the coin. You want it to be normal but yet you want it to be special."
A screenshot of Nasa's live video of the spacewalk. Photo: Supplied / NASA
The first woman to spacewalk was the Russian Svetlana Savitskaya, who went outside the USSR's Salyut 7 space station for three hours, 35 minutes on 25 July 1984. She was accompanied by fellow cosmonaut Vladimir Dzhanibekov.
The first person in history to spacewalk was Soviet cosmonaut Alexei Leonov, who died earlier this month aged 85.
On Tuesday, Nasa unveiled a prototype for a new spacesuit that might be worn by the next astronauts on the Moon. It said the new Moon suit, known formally as the Exploration Extravehicular Mobility Unit (xEMU), is designed to give the wearer a customised fit whatever their shape or size.
- Reuters/ BBC