Engineers cheered as electricity coursed through Space Shuttle Endeavour Thursday for the first time in two years, signaling the end of the orbiter's major modification period at NASA's Kennedy Space Center in Florida.

"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 Space Shuttle Program Manager Wayne Hale.

Engineers and technicians spent 900,000 hours performing 124 modifications to the vehicle. These included all recommended return to flight safety modifications, bonding more than 1,000 thermal protection system tiles and inspecting more than 150 miles of wiring throughout Endeavour. Eighty five of the modifications are completed, with work on the additional 39 modifications continuing throughout the next few months.

Two of the more extensive modifications included the addition of the multi-functional electronic display system, or "glass cockpit," and the three-string global positioning system that improves the shuttle's landing capability.

The glass cockpit encompasses a new, full-color, flat-panel display system that improves interaction between the crew and orbiter with easy-to-read graphics portraying key flight indicators like attitude display and mach speed. Endeavour was the last vehicle in the fleet to receive this system.

The three-string global positioning system would allow Endeavour to make an emergency landing at any runway, provided it was long enough to accept a space shuttle. The previous system, TACAN, or Tactical Air Navigation System, only allowed for a landing at a military base.

"When Endeavour was powered up for the first time, the team cheered at the completion of all of their hard work and accomplishments during the modification period," said Tassos Abadiotakis, Endeavour's vehicle manager. "The team worked tirelessly to ensure the vehicle progressed though the modification period on time and on budget."

Shuttle major modification periods are scheduled at regular intervals to enhance safety and performance, infuse new technology and allow for thorough inspections of the airframe and wiring of the vehicles. This was the second of these modification periods performed entirely at Kennedy Space Center. Endeavour's previous modification was completed in March 1997.

Endeavour is now beginning 10-12 months of launch processing and power-up testing for a future space shuttle flight as soon as late next year.

For the latest information on NASA's Space Shuttle Program on the Internet, visit:

http://www.nasa.gov/shuttle