Flight Engineers Chris Cassidy of NASA and Luca Parmitano of the European Space Agency will focus primarily on completing tasks they began on their previous spacewalk on July 9.
"The opening of the Quest airlock on the American segment of the ISS is scheduled for 04.15 pm Moscow time [12.15 GMT]…The astronauts will spend more than six hours outside the station,” a spokesman for the Russian Mission Control said.
The astronauts will finish the installation of bypass jumpers to provide power redundancy to critical station components, route additional cables for a new Russian Multipurpose Laboratory Module (MLM) set to arrive in December, and perform a variety of additional maintenance tasks.
It will be the 171st spacewalk in support of station assembly and maintenance, the fifth conducted at the station this year, the sixth of Cassidy’s career and the second for Parmitano, NASA said Monday on its website.
The launch of the Russian MLM module was initially slated for the first half of 2011, but has since been repeatedly delayed. The module is being constructed by the Khrunichev Space Center and RKK Energia.
MLM will carry out a variety of scientific and commercial projects as well as perform a range of other functions including life-support, steering the ISS with an attached motor, docking with cargo vessels and fuel transit from Progress cargo ships to the Zvezda module.