CAPE CANAVERAL, Florida (AFP) – NASA gave the go-ahead for Thursday's launch of the Discovery space shuttle mission to the International Space Station, but warned of another delay if weather does not improve.

Mission experts agreed on the launch attempt after a close study of the latest electrical glitch found that a circuit-breaker was the origin of a cockpit problem, not the main engine controller which would have been more serious.

But after three postponements so far to the Discovery's final flight before it is retired, NASA experts said gloomy weather could push back efforts again, and conditions would be reviewed Thursday morning ahead of the 1929 GMT launch.

"From a vehicle prospective we are ready to go," said mission management team leader Mike Moses.

"The weather still looks pretty bad for tomorrow," he added. "There's a chance we'll decide not to spend one of our (launch) opportunities.

The weather forecast at present calls for only 20 percent favorable conditions for launch. A green light from the mission managers would begin shuttle fueling operations, which normally take three hours and are scheduled to start at 1005 GMT.