British astronaut Tim Peake has ventured outside the International Space Station into the open space, becoming the first British person to have performed a spacewalk.
The Chichester-born astronaut was accompanied by his American colleague Tim Kopra as they set out shortly before 1pm GMT to replace a failed power regulator, install a valve and attach cables to the outside of the station.
The nation followed Peake’s adventure closely, with some high-profile well-wishers sharing their excitement on Twitter.
“Good luck @astro_timpeake we're all watching, no pressure! Wishing you a happy stroll outdoors in the universe. All the best,” tweeted former Beatle Paul McCartney while Prime Minister Cameron said: "Good luck to @astro_timpeake on today's space walk. The country will be watching you make history.”
Peake, who arrived at the orbital outpost one month ago, had spent months practicing for the spacewalk in a special Nasa swimming pool ahead of his departure.
"A proud moment," said Peake, as he floated outside the airlock some 400km above the Earth.
About three hours into the six-hour spacewalk, the astronauts successfully replaced the 90-kg voltage regulator that failed in November. Since then, the station has been running on its remaining seven power channels, but NASA was concerned a second failure could be a problem.
NASA astronaut Reid Wiseman, who performed a similar spacewalk in 2014, guided them from mission control in Houston, USA.
"Looking great out there on the top of the world," Wiseman radioed to the spacewalkers, who had to wait for night-time passes to carry out the work safely when the station’s solar panels are not receiving any charge.
After completing the replacement, they moved on to install cables for a docking port for Nasa’s future manned spaceships.
43-year old Peake is the first Briton on a mission to the ISS under the flag of the European Space Agency. His six-month mission, named Principia after the cornerstone work of legendary physicist Isaak Newton, sees him working on dozens of scientific experiments as well as heavily engaging with the public as part of an outreach programme designed to promote interest in science, technology and engineering disciplines.