Discovery (finally) good to go on 24 Feb

NASA has announced it has resolved the problem with Discovery's external fuel tank and the shuttle is good to launch on its STS-133 mission to the International Space Station on 24 February.

The vehicle was grounded on 5 November by a fuel leak caused by cracks in two of the tank's 108 U-shaped aluminium brackets, known as "stringers".

Two months of head-scratching have led the space agency to conclude that the problem was caused by "a combination of manufacturing issues and stresses put on the tank when it is filled with supercold liquid oxygen and liquid hydrogen", according to shuttle programme manager John Shannon.

Engineers will now install supportive reinforcements on the stringers in what Shannon described as "an elegant fix to the problem".

He added: "I'm very confident that we have finally figured this out."

Discovery will carry the converted multi-purpose logistics module Leonardo, now destined to become permanent extra storage at the ISS, plus essential spares for the orbiting outpost.

The final shuttle mission, Endeavour's STS-134, will now probably be knocked back from 1 April to 18 April, to allow for additional testing on its external fuel tank, the space agency noted yesterday.

Whether commander Mark Kelly is on board remains to be seen. He's taken a leave of absence to be with his wife Gabrielle Giffords, who's recovering from a gunshot wound to the head she received last Saturday in Tuscon, allegedly at the hands of Jared Loughner.

NASA's associate administrator for space operations, Bill Gerstenmaier, said: "We're going to let Mark decide what he needs to do." ®