Two US astronauts conducted a spacewalk outside the International Space Station on Friday, to connect one of two docking adapters set to be used for future spacecraft arrivals.
The more-than-six-hour-long project was being broadcast live on NASA TV.
Astronauts Kate Rubins and Jeff Williams can be seen tinkering on the adapters while orbiting some 400 kilometres above Earth. Their white spacesuits starkly contrast the black abyss in the background.
This was Rubin's first spacewalk and Williams' fourth time venturing outside the station.
The docking adapters will be used for Boeing and SpaceX commercial crew spacecrafts and are an "important milestone in the efforts to include manned space flights from the United States again," NASA said.
After ending their space shuttle program in 2011, US astronauts must be flown to the ISS from the Baikonur Cosmodrome in Kazakhastan via Russian Soyuz shuttles.
The ISS is currently operated by five spaces agencies representing the United States, Russia, Japan, Europe and Canada.
Three Russians and a Japanese astronaut are also currently stationed on the orbiting laboratory.