The decision was taken by the director of the orbiting space lab, Mike Suffredini, on Monday and relayed Tuesday to the Discovery crew by mission control in Houston.
As the US space agency made preparations for the prolonged mission, two astronauts from the shuttle embarked on the third of five spacewalks outside the space station.
After less than three hours, astronauts Scott Parazynski and Doug Wheelock successfully attached the Port 6 truss segment, a large metal beam needed to deploy a third solar antenna for the station.
They then began removing covers or 'shrouds' from electronic equipment boxes on the truss which had been stored on the top of the space station for seven years.
With the truss in place, another set of solar arrays were to be unfurled later, NASA television said.
In a fourth space walk set for Thursday, astronauts will examine the crucial rotary joint for the solar arrays after having found small metal shavings and unusual wear in the joint in an earlier space walk on Sunday.
The inspection will require a space walk of more than six hours as the Discovery remains docked at the ISS.
As a result, the shuttle is scheduled to return to Earth on November 7 instead of November 6.
The problem was not insurmountable and it was merely a question of time space, station director Suffredini said.
Suffredini also said the complication would not affect plans for another shuttle mission in December to deliver Europe's Columbus laboratory to the station.
The rotary joint helps spin a set of the power-generating solar panels that were installed four months ago. © 2007 Australian Broadcasting Corporation
