Shuttle lift-off faces further delay

Nasa has delayed the liftoff of space shuttle Endeavour yet another day, to Wednesday.

A valve change was taking longer than expected.

The valve in Endeavour's left orbital-manoeuvring system malfunctioned during the final few hours of the countdown on Thursday.

The National Aeronautics and Space Administration fixed it, only to be thwarted at launch time by thunderstorms.

The same problem with the nitrogen-gas valve appeared again over the weekend.

Mission managers ordered a valve replacement on Saturday and aimed for a Tuesday launch, but have postponed the flight one more day to give workers time to finish the job.

This is the fourth delay in less than a week for the mission to deliver a new crew and supplies to the International Space Station.