Washington, Nov 17 (IANS): At the age of 56, NASA astronaut Peggy Whitson is set to be the oldest woman in space when she launches for a six-month stay aboard the International Space Station from the Baikonur Cosmodrome in Kazakhstan on Friday.

Oleg Novitskiy of the Russian space agency Roscosmos, and Thomas Pesquet of ESA (European Space Agency) will accompany the veteran astronaut as crew members of Expedition 50/51. It will be Whitson's third long-duration mission to the International Space Station.

During their stay aboard the orbital complex, Whitson will become the first woman to command the space station twice, NASA said.

With her scheduled launch to the space station on Friday, Whitson is set to break the record of Barbara Morgan who flew to the space station at the age of 55 in 2007. Morgan was part of the NASA Teacher in Space Programme.

Whitson, an Iowa native, completed two six-month tours of duty aboard the station for Expedition 5 in 2002, and as the station commander for Expedition 16 in 2008.

She has accumulated 377 days in space between the two missions, the most for any US woman at the time of her return to Earth. Whitson has also performed six spacewalks, totaling 39 hours and 46 minutes, according to the astronaut's biography at NASA.

Her first tenure as commander was in 2007, when she became the first woman to hold this post.

Whitson has an advanced degree in biochemistry, and prior to her selection as an astronaut candidate in 1996, she served in prominent medical science research and supervisory positions at NASA.