The astronauts of the space shuttle Discovery have completed the second spacewalk of the two-week mission to the International Space Station (ISS), and are preparing for the third.

During the spacewalk, one of the crew discovered metal shavings inside a rotary joint on a solar array. The joint is needed to allow the panels to turn to track the sun, but for now NASA has elected to limit its movement to prevent the shavings causing serious damage.

The discovery explains current spikes that have been registered from the array over the last six weeks or so, NASA told US reporters. As the array's movement is being restricted, it will not be able to supply its maximum power. This makes it all the more important that the crew successfully completes the relocation of a 17.5 ton solar array truss during this mission.

The array, which astronauts are currently manoeuvring with the robotic arms on both space shuttle and station, needs to be reinstalled on the space station to provide power to the European Space Agency's Columbus lab unit. Columbus is due to be connected to the Harmony docking station on the next shuttle mission.

Discovery did bring spare parts, including new bearings, for the joint. However, NASA says the crew is unlikely to have time to deal with the problem. Instead, Discovery's crew will make further inspections that will allow the full-time ISS crew to make repairs later. ®

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