MOSCOW, September 6 (RIA Novosti) - NASA astronaut Danny Olivas and ESA astronaut Christer Fuglesang began the third and final spacewalk of the STS-128 mission to the International Space Station, NASA said on Sunday.

"The spacewalkers will deploy an attachment system that will be used to hang spare parts on the station's truss," NASA said on its website. "They also will replace a device designed to help the station determine its position relative to the Earth."

The spacewalk is expected to last 6.5 hours.

During the first two spacewalks the astronauts have replaced an ISS ammonia coolant tank.

On Tuesday, the Discovery will undock from the ISS. It is scheduled to return to Earth on September 10.