Two Discovery astronauts stepped outside the International Space Station on Saturday morning to begin their first spacewalk, NASA television showed.

Mission specialists Piers Sellers is the lead spacewalker and is wearing a spacesuit with red stripes. And Mike Fossum is wearing an all white suit. They are slated to work outside the station and space shuttle discovery for 6.5 hours.

The astronauts have two major tasks to tackle during the excursion. The first is to work on the station's mobile transporter. Then, the orbital duo will test the ability of the shuttle's robotic arm and extension to serve as a platform for astronauts making heat shield repairs.

They are being assisted from the inside the shuttle/station complex by pilot Mark Kelly, who is the spacewalk coordinator. Mission specialists Lisa Nowak and Stephanie Wilson operate the shuttle and station robotic arms.

Source: Xinhua