NASA postponed Friday's scheduled launch of the space shuttle Endeavour for at least two days because of a technical problem.
The space agency said two heaters on one of the shuttle's three onboard power units had failed and the launch was delayed at least until Sunday.
Endeavour had been due to blast off at 3:47 p.m. EDT (1947 GMT) on a mission to deliver a pioneering physics experiment to the International Space Station.
President Barack Obama and his family had been scheduled to attend the launch, which was to be the 134th and next to last for the U.S. space shuttle program. NASA is retiring its shuttles after a cargo run by the shuttle Atlantis this summer.
U.S. Representative Gabrielle Giffords, who is married to Endeavour commander Mark Kelly, was at the space center for the launch attempt.
Giffords, an Arizona Democrat, was gravely injured during an assassination attempt Jan. 8 outside a Tucson, Arizona, grocery store in which six people were killed and 12 others were injured. She has not been seen publicly since the attack.
(Editing by Jane Sutton and Eric Beech)
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