At 23.50 Moscow time members of the crew of the 4th long-term expedition on the International Space Station (ISS) - Russian cosmonaut Yuri Onufriyenko and US astronaut Carl Walz - will begin a walk in open space. As head of the press service of the Russian Mission Control Centre Valery Lyndin said, the spacemen will spend six hours in open space. They have to fasten the second erection truss-crane to the Russian berth Piers situated at the Zvezda Russian module. They will also install a receiving radio aerial. Second US astronaut Daniel Bursch will control and safeguard the spacemen's actions, staying inside the station. It will be the sixth walk of Russian cosmonaut Yuri Onufriyenko in open space. He made his five previous walks during his first flight on the Russian station Mir. For US astronaut Carl Walls it will be the second space walk; he made his first walk during the visit to the Russian station Mir in 1996.