NASA on Friday said that it cut short a spacewalk at the International Space Station (ISS) after an astronaut reported a leak in his spacesuit helmet. British astronaut Tim Peake, who on the mission became the first astronaut from his country to walk in space, and US astronaut Tim Koprawere did spacewalk with the primary goal of their outing when Kopra reported the formation of a water ball in his helmet.

During an interview on NASA TV, flight director Royce Renfrew said that the astronauts were safe, but the space agency curtailed the spacewalk as a precaution.

In December, the 43-year-old Peake, former army major, blasted off to the space station under a six-month mission for the European Space Agency (ESA), and become the first Briton in space since 1991, when Helen Sharman travelled on a Soviet spacecraft for a time span of eight days.

In Britain his mission has received a lot of attention, with news channels beaming the spacewalk’s live coverage. British musician Paul McCartney posted on Twitter, “We're all watching, no pressure! Wishing you a happy stroll outdoors in the universe”.

About three hours into spacewalk on Friday, the 52-year-old Kopra reported that his helmet pad was moist and a water ball collected in his helmet, forcing the space agency to end the mission. By the time Kopra and Peake came back to the airlock, the leak had increased. Later, Kopra told ground controllers that the leak was very noticeable.

NASA has made its flight rules stricter after July 2013, when a spacesuit worn by Italian astronaut Luca Parmitano leaked during a spacewalk, almost leading him to drown.