Shuttle rollout delayed by crack

The crack is no cause for concern, Nasa says

The moving of the Discovery space shuttle to the launch pad has begun after the discovery of a crack in a fuel tank led to a two-hour delay.

The US space agency Nasa said the flaw in an external tank's foam insulation posed no reason for concern.

Discovery is due to be sent to the international space station in the coming months.

It will be the first shuttle Nasa has launched since the Colombia tragedy in 2003, in which seven astronauts died.

Columbia's disintegration was blamed on a foam chunk that fell off the tank during lift-off.

'Not major'

Nasa spokeswoman Jessica Rye said images of Discovery's hairline crack had been examined by the tank manufacturers.

The space agency concluded that no repairs were necessary and began moving Discovery from its assembly building to the launch pad, four miles away.

It will take approximately eight hours for engineers to move the shuttle.

Following the 2003 Columbia disaster, the tank has been revamped for Discovery's flight.

"It doesn't sound like it's a major issue, but because the foam is a sensitive issue we want to make sure we're in a safe and right configuration," Ms Rye said when the crack first came to light.

Discovery's first launch window runs between 15 May to 3 June - during which time the international space station will be in an appropriate position.