NASA astronauts on ISS conduct first spacewalk of year

Two NASA astronauts have successfully conducted the first spacewalk of the year, replacing a degraded robotic "hand" outside the International Space Station (ISS).

Expedition 54 flight engineers Mark Vande Hei and Scott Tingle spent seven hours and 24 minutes yesterday working outside the orbiting laboratory.

Their primary task was to swap out one of the two "hands" on the Canadarm2 robotic arm.

Known as a latching end effector, or LEE, the device is used to grapple and release visiting cargo spacecraft, 'Space.com' reported.

After removing protective covers, they carefully installed the 200 kilogramme piece of equipment onto the end of Canadarm2 as Japanese astronaut Norishige Kanai operated the robotic arm from inside the station.

The ground control team at NASA's Johnson Space Center in Houston fixed the glitch by rebooting the robotic arm, and the two astronauts were able to finish their spacewalk almost an hour behind schedule.

The event marked the 206th spacewalk conducted by ISS astronauts in support of the station's assembly and maintenance.

It was the first spacewalk this year and the first of two NASA has planned for this month.