Two US astronauts embarked on a spacewalk Thursday to install a pair of high-definition video cameras designed to help visiting commercial spaceships dock at the International Space Station.
The planned 6.5 hour outing by veteran NASA astronauts Drew Feustel and Ricky Arnold formally began when they switched their suits to battery power at 8.06 am (1206 GMT), then floated out into space.
The work is part of an ongoing upgrade to the $100 billion orbiting outpost, adapting it for the arrival of US commercial vehicles carrying astronauts.
Boeing and SpaceX are completing the final touches on their respective crew capsules, and are expected to begin regularly transporting astronauts to the ISS in 2019. The first test flights could happen later in 2018.
The new cameras, located near an international docking adapter on station's Harmony module, "will provide enhanced views during the final phase of approach and docking of the SpaceX Crew Dragon and Boeing Starliner," said a NASA statement.
Astronauts have not launched from US soil since 2011, when the 30-year US space shuttle program came to an end.
In its absence, the world's astronauts have paid Russia upwards of $70 million per seat for a ride to the ISS aboard the Soyuz spaceships.