NASA has completed a swathe of modifications to the Space Shuttle Endeavour to bring the craft up to the new safety standards required by the Return to Flight recommendations. The shuttle was powered up at the Kennedy Space Center, yesterday, for the first time in two years.

Endeavour was commissioned in the aftermath of the Challenger disaster, and was completed in 1991. Getting it to meet the new standards has not been a small task. In total, engineers and technicians have spent 900,000 hours making 124 modifications, NASA says, including all the return to flight requirements, securing more than 1,000 thermal insulation tiles, and checking over 150 miles of wiring.

"Having three operational vehicles in the fleet affords the shuttle program great schedule flexibility as we move toward flying safely and completing the international space station," said Wayne Hale, the space shuttle program manager.

Despite the reports of cheering from engineers when the power was switched on, the job is not finished yet. Of the 124 modifications, only 85 are fully finished, so work will continue for another few months.

The shuttle boasts some nifty improvements, though. For instance, it now has a new electronic display system, known as a "glass cockpit", bringing it into line with the rest of the fleet. It also has a new three string GPS which will allow it to make emergency landings at any airport with a long enough runway. The old system restricted it to military air bases.

Engineers will now begin a 12-month period of launch processing and power-up testing ahead of a possible flight in late 2006. ®