Two female NASA astronauts have sealed their place in history with an all-woman spacewalk outside the International Space Station.

Flight engineers Christina Koch and Jessica Meir ventured out into the vacuum of space on 18 October to replace a failed power controller, also known as a battery charge-discharge unit (BCDU).

The BCDU regulates the charge to the batteries that collect and distribute solar power to the orbiting lab’s systems.

Both astronauts were also able to complete tasks including the installation of a stanchion on the Columbus module for support of a new external European Space Agency payload platform called Bartolomeo, scheduled for launch to the station in 2020.

The astronauts were assisted in their mission by Commander Luca Parmitano of ESA and NASA Flight Engineer Andrew Morgan. Parmitano operated the Canadarm2 robotics arm and Morgan provided airlock and spacesuit support.

It was the first spacewalk for Meir and the fourth for Koch, who now has spent a total of 27 hours and 48 minutes spacewalking.

Photo: NASA

It is the first spaceflight for both women, who were selected in the 2013 astronaut class that had equal numbers of women and men.

Koch arrived to the orbiting laboratory in March 2019 and will remain in space for an extended duration mission of 11 months to provide researchers the opportunity to observe effects of long-duration spaceflight on a woman. This will help with preparations for future human missions to the Moon and Mars.

In a call with President Trump, Meir paid homage to other female astronauts.

“There have been many other female spacewalkers before us, this is just the first time there have been two women outside at the same time,” Meir said.

“We were the crew that was tasked with this assignment.

“At the same time, we recognise that it is a historic achievement and we do of course want to give credit to all those who came before us.

“There have been a long line of female scientists, explorers, engineers, and astronauts, and we have followed in their footsteps to get us where we are today.”

NASA states on its website that the faulty BCDU will be returned to Earth on the next SpaceX Dragon resupply ship for inspection.

Station managers will reschedule the three battery replacement spacewalks for a future date.