Article Posted on : - Sep 06, 2009

Mission specialist Christer Fuglesang exits the International Space Station to start the third and final STS-128 spacewalk. Image credit: NASA TV

WASHINGTON (PTI): Astronauts from the US space shuttle Discovery ventured out of the International Space Station for a third spacewalk that will be the last of their mission.

NASA astronaut Danny Olivas and European Space Agency astronaut Christer Fuglesang left the ISS at 0209 IST on Saturday for what is expected to be a 6.5 hour spacewalk, the US National Aeronautics and Space Administration said.

The pair are expected to �deploy an attachment system� and �replace a device designed to help the station determine its position relative to the Earth,� NASA said.

Fuglesang, of Sweden, and Olivas on Friday installed a liquid ammonia tank to keep the space station cool and completed several other tasks, including bolting portable foot restraints on the orbiter's truss.

The pair returned to the decompression chamber after six hours and 39 minutes in space, NASA said, and after bolting the 800-kilogram tank into place and linking up electrical and fluid lines.

The spacewalkers also moved a spent ammonia tank, which was removed Wednesday, into the shuttle's cargo bay to be taken back to Earth.

With this week's outing Fuglesang � who was the first Swede in space in December 2006 �became the first astronaut outside the United States or Russia to participate in more than three spacewalks.