The final launch of the space shuttle Endeavour was delayed today for at least three days.
The shuttle was scheduled to blast off from NASA Kennedy Space Center on its final mission. But Launch Director Mike Leinbach opted to postpone the mission "because of an issue with Auxiliary Power Unit 1 heaters,'' according to NASA's website.
The mission commander for the 14-day trip to the International Space Station will be astronaut Mark Kelly, husband of Arizona Rep. Gabrielle Giffords, who survived a shooting rampage in Tucson earlier this year. She is expected to attend the launch.
Endeavour was built in Palmdale to replace the destroyed Challenger shuttle. When its final mission is completed, Endeavour will have traveled 115 million miles during 25 flights, carrying 139 people into orbit, according to NASA.
It was the final shuttle built, but was the first to include safety improvements such as a drag parachute deployed on landing, and nose-wheel steering to prevent wear on the tires during runway rollout. Construction began in 1987, the year after the space shuttle Challenger blew up shortly after launch. Endeavour was completed in 1991.
During the shuttle's last mission, its crew will be delivering to the ISS the Alpha Magnetic Spectrometer, two communications antennas, a high- pressure gas tank, an ammonia tank assembly, circuit breaker boxes, a computer for the station's Canadarm2 robotic system and a spare arm for the Dextre robot, NASA said.
The 30-year space shuttle program will end for good after the final launch by Atlantis, planned for late June.