THE FINAL LAUNCH of NASA’s space shuttle Endeavour has been delayed again after its Friday launch was cancelled due to a mechanical fault.

Preparations for Friday’s launch had progressed to the extent that the shuttle’s crew was being driven to the launch pad when they heard that a faulty heater part meant Endeavour would not be taking off.

US Congresswoman Gabrielle Giffords, who was seriously injured when shot in the head in an attack on 8 January, had travelled from her Houston hospital to Florida to watch her husband astronaut Mark Kelly lead the space mission.

The six-person crew is due to travel to the International Space Station to carry out maintenance work and to deliver a particle physics detector called the Alpha Magnetic Spectrometer (AMS) to the ISS.

The ageing shuttle has operated missions for 19 years and is due to be retired after this operation and sent to the California Space Centre in LA.

NASA spokesperson Allard Beutel said technicians will replace a switch box inside the shuttle’s engine compartment and the operation will require two days of testing after the new box goes in. Beutel said that no new date has been set for the delayed launch, but it would be no earlier than the end of this week.

A military satellite is due to launch on Friday and if it is takes off before Endeavour, NASA will have to allow some time between the two launches.

- Additional reporting by the AP