Nasa to launch newest space telescope on Christmas Day

Nasa announced the latest delay Tuesday. Upper-level high wind could force a rocket off-course or even damage or destroy it.

The $10bn infrared observatory is considered the successor to the Hubble space telescope, in orbit since 1990.

During a news conference Tuesday, Nasa officials said the rocket and telescope were in good shape and that the only lingering, though tolerable, problem was an intermittent communication relay between the two.

The issue earlier forced a two-day delay; a clamp that inadvertently jolted the telescope at the launch site had prompted a four-day slip.

These last-minute snags come after years of delays and cost overruns for Webb, the biggest and most powerful science observatory ever built for space.

Nasa is partnering with the European and Canadian space agencies on the project.