Nasa inspecting shuttle

Nasa technicians carried out new tests yesterday to check whether space shuttle Atlantis was damaged by a lightning strike and the US space agency said the ship's launch would be delayed at least until tomorrow.

Nasa is seeking to determine whether the shuttle's twin solid rocket boosters could have been affected by a huge bolt of lightning that hit the Florida launch pad on Friday afternoon.

"Mission managers have determined Shuttle Atlantis will not launch before Tuesday (tomorrow)," Nasa said in a statement.

The ship had originally been scheduled to launch yesterday, and was then set for today. Nasa said the additional delay was due to "the need for additional time for further analysis of the shuttle and ground systems."

"They're looking to see if the solid rocket boosters got a high voltage or currents from the strike," spokesman Allard Buetel said.

Hurricane Ernesto could also be a concern. The most likely path of the storm, which was moving through the Caribbean Sea yesterday, could take it ashore on the west coast of Florida and across the state north of Cape Canaveral on Thursday.

The shuttle's six astronauts are scheduled to spend 11 days in orbit to deliver and install a 16-tonne power module to the International Space Station.

It would be the first station assembly mission in nearly four years and follows a successful mission of shuttle Discovery last month to assess safety upgrades made after the February 2003 shuttle Columbia disaster.

Columbia was hit by a piece of foam insulation that fell off its fuel tank during launch. Damage from the impact triggered the shuttle's breakup as it flew through the atmosphere. All seven astronauts aboard died.

The concern with the Atlantis' boosters, the only system that was not powered on at the time of the lightning strike, centres around its many ordnance devices, all of which rely on electronic signals to work.

While lightning strikes are far from unusual in central Florida, particularly in the summer and the Atlantic hurricane season, the bolt that hit the shuttle's launch pad on Friday was the largest ever recorded at the Kennedy Space Centre.

The complex has a lightning protection system, which spared the shuttle a direct hit. But engineers were studying potential problems with an electronic device and ordnance on a hydrogen vent line that is part of ground support equipment.

A Reuters photographer saw Nasa technicians in fire retardant jump-suits inspecting a gaping access hatch near the top of the shuttle's port side rocket booster yesterday morning.

A massive crane was later rolled toward the launch site, but details of the hands-on inspection work were not immediately available.

The Atlantis mission is a critical part of Nasa's efforts to finish building the International Space Station before the shuttle fleet is retired in 2010.