The final mission to service the Hubble space telescope has slipped deeper into next year, Nasa has announced.

Officials said the delay would give engineers extra time to prepare a spare control unit needed to replace one that broke on the observatory last month.

Hubble was taken offline for four weeks by the failure but has since been re-booted using a back-up system.

Meanwhile Nasa said the space shuttle Endeavour would launch on 14 November to the Intern