The space shuttle Discovery has uncoupled from the International Space Station and is heading back to Earth, after an eventful 11 day stay in orbit.

The shuttle's journey home will take two days, and it is scheduled to land back at Kennedy Space Centre in Florida on Wednesday afternoon.

The crew of Discovery spent time this weekend on an unscheduled and very risky spacewalk to repair a tear in one of the solar arrays. The solar panel was damaged after it was installed earlier in the mission, and was being unfurled.

The damage meant the solar wing couldn't be locked into position, according to reports, but after a home made repair kit of "cufflinks" was dispatched with mission specialist Scott Parazynski, the array is back in working order. If it hadn't been fixable, the unextended wing would have undermined the strength of the ISS' structure.

The spacewalk was particularly hazardous because the solar array was charged and could have given Parazynski a serious shock if he had touched it. His boots and tools were insulated for protection.

The crew also identified a problem in the rotary joint of another set of solar arrays. The affected area was installed in June, but had been behaving unusually. Astronauts from Discovery inspected the problem area and determined that metals shavings were lodged in the circular joint.

Although the crew did have spare parts to make the repair, doing so would have put too much pressure on the schedule, so it is likely that the remaining ISS crew will deal with it as part of their routine station maintenance.

NASA says that even without the repair, the space station can power the Columbus science lab from ESA, due to be delivered on the next shuttle flight. The future for the Japanese Kibo lab is less assured, the space agency said. ®

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