Shuttle mission may be extended

Nasa has asked its shuttle astronauts to take a closer look at the gears that control the international space station’s solar wings to try to locate a problem in the mechanics of the system.

The “exploratory surgery” will almost certainly keep the shuttle Discovery in orbit for an extra day.

During a spacewalk already planned for today, astronaut Scott Parazynski will inspect a good rotary joint that turns the space station’s left set of solar wings towards the sun.

Nasa wants to see what a perfectly running unit looks like to compare it to the problematic one on the opposite side.

Yesterday, spacewalker Daniel Tani found black dust that resembled metal shavings inside the motorised joint that controls the right set of solar wings.

He said yesterday that it was instantly apparent to him something was wrong. The dust was everywhere, and the spinning mechanism was not shiny and clean like it should have been for something launched just four months ago, Tani said.

At least some of the shavings are steel and could be from the bearings inside the joint, said Mike Suffredini, Nasa’s space station programme manager.

The time-consuming work would be conducted on Thursday during the fourth spacewalk planned for Discovery’s construction mission.

As of now, Discovery is supposed to undock from the space station on Sunday and return to Earth on November 6. Adding a 15th day to the mission would delay both events by a day.