Watch live as Nasa astronauts make an unscheduled spacewalk to repair the ISS

Astronauts Tim Kopra and Scott Kelly left the ISS to make urgent repairs to the station

Nasa astronaut Garrett Reisman makes repairs to the ISS during a spacewalk in May 2010 (NASA via Getty Images)

Two Nasa astronauts are currently on an unscheduled spacewalk in order to make repairs to the International Space Station (ISS).

Astronauts Tim Kopra and Scott Kelly, who is currently in the ninth month of his year-long stay aboard the ISS, donned their spacesuits and headed out into the vacuum of space in order to make repairs following an unexpected fault.

The problem is with the mobile transporter - a kind of rail car which runs along the side of the ISS, carrying equipment and important research tools across the station.

The mobile transporter itself can be used to make repairs, and is vital in bringing in cargo and other craft to the ISS - so when it gets stuck in place, problems can occur.

Nasa is streaming the whole spacewalk online, using the astronaut's helmet-mounted cameras to broadcast the amazing and risky operation to the world.

This is only Kopra's second spacewalk, and Kelly's third. Spacewalks are amazing to watch, but they're much riskier for the astronauts, compared to the relative safety of being inside the ISS.

Making the repairs should cut down on the number of urgent spacewalks needed in future, helping the operations on board the ISS to run much more smoothly.

Tim Peake, the first Briton to become a fully-fledged astronaut, remains inside the ISS, along with Russian cosmonauts Sergey Volkov, Yuri Malenchenko and Mikhail Kornienko, who is also spending a year in space.