Washington, July 16 (DPA) Space shuttle Endeavour blasted off Wednesday on its sixth attempt to launch since June, headed to the International Space Station to expand Japan's Kibo module.

The seven-member crew is to deliver an outside porch on the module at the station to expose scientific experiments to the extremities of space.

The mission has suffered a slew of delays that kept the craft on the ground for weeks longer than planned.

A planned Sunday launch was cancelled due to storms and a Saturday launch was also scrubbed due to lightning the night before that struck the launch pad, but spared the shuttle itself.

On Monday, stormy weather again grounded the spacecraft.

NASA was forced to postpone the launch twice in just four days last month, after technicians detected hydrogen gas leaks during fuelling, just hours before scheduled liftoff.