Atlantis astronauts begin second spacewalk

Two shuttle astronauts have floated out into space to put finishing touches on the International Space Station's new science lab.

Thomas Jones and Robert Curbeam Jr. assisted astronaut Marsha Ivins as she used the shuttle's robotic arm to place a docking port at the end of Destiny, space station Alpha's new science laboratory.

The port will be where the shuttle docks, or attaches itself, to the station on future missions.

The spacewalkers also planned to attach various other equipment and fixtures to the exterior of the lab, including the future connection point for the space station's robotic arm - due to be brought up in April.

The spacewalk is scheduled to last just more than six hours.

At the end of the spacewalk, space station flight controllers are to send Destiny's computers commands to begin spinning four large gyroscopes on Alpha, which will eventually help control attitude, saving station fuel.