Shuttle Launch Could Be Called Off

Tomorrow's scheduled launch of the space shuttle Discovery could be called off because of a 20cm crack in the insulation covering its fuel tank, Nasa revealed today.

Nasa managers were to decide later today whether to postpone the launch, after the crack was spotted during a routine inspection.

They had previously scrubbed launch plans over the weekend because of poor weather and had removed fuel from the tank.

The inspectors found the 20cm deep and 12cm long crack in the insulating foam on a bracket near the top of the external fuel tank. Nasa is considering whether the crack can be fixed in time for a lift-off tomorrow.

"We don't know if it's a problem or not," Nasa spokesman George Diller said today.

If the launch goes ahead, it will be only the second lift-off of a space shuttle since the 2003 Columbia disaster.

Concerns about cracks in the fuel tank's foam insulation have dogged the programme since Columbia exploded over Texas in February 2003, killing its seven crew members. A chunk of flyaway foam damaged Columbia's wing during lift-off, allowing superheated gas to penetrate the shuttle when it re-entered the atmosphere.

Nasa tried to fix the problem before trying another launch, but more foam broke off Discovery's redesigned tank when it was last launched in July 2005, barely missing the shuttle.

Nasa administrator Michael Griffin then decided the shuttle should go into orbit despite the concerns of two top agency managers who wanted additional repairs to the foam insulation.

The mission for Discovery's crew this time is to test shuttle inspection techniques, deliver supplies to the international space station and drop off German astronaut Thomas Reiter for a six-month stay.

The weather forecast for a Tuesday lift-off was better than it was on Sunday or today. But Kaleb Nordgren, a shuttle weather forecaster, said there was still a 40% chance that storms at launch time would prevent lift-off.

Nasa has spent more than $1bn (£540m) in the last three years fixing problems on the shuttle, which is due to be decommissioned in 2010.

It could be grounded sooner if the current problem proves significant.