Houston/Moscow, Sep 13 (DPA) US astronaut Dan Burbank and Canadian Steve MacLean left the International Space Station (ISS) Wednesday for the second of three planned space walks.

The two astronauts started the six-hour sortie to prepare the three-metre rotary joint for the arrays that should double the station's solar power intake.

"See you in a couple of hours," the astronauts from the visiting Atlantis space shuttle told ground controllers as they set to work on the joint that will turn the panels to track the sun.

Operating in the confines of their bulky space suits, they must remove 22 supports and fasteners as well as protective covering from the unit.

A final space walk on Friday will upgrade communications systems.

Atlantis crew members successfully completed the first space walk Tuesday to prepare the new equipment.

They have no time to waste in installing the panels, as the scheduled arrival of a Russian Soyuz spacecraft with a new ISS crew on Sep 20 means the shuttle must undock beforehand.