CAPE CANAVERAL, Florida NASA Sunday delayed the launch of space shuttle Endeavour to no earlier than May 8 as work continues to resolve an electronics problem that scuttled Friday's launch attempt, officials said.
NASA tried to launch Endeavour Friday on its 25th and final flight to deliver the $2 billion Alpha Magnetic Spectrometer particle detector to the International Space Station.
A problem with a heating system on one of the ship's hydraulic power generators prompted managers to halt the countdown. The heaters keep fuel from freezing in the line, preventing it from rupturing in the cold vacuum of space.
NASA was hopeful that the problem would have an easy solution and had re-targeted Endeavour's launch for Monday, but further trouble-shooting indicated the glitch was more complicated than officials hoped initially.
Workers will replace a microwave-sized electronics box, located in the shuttle's rear engine compartment, which routes power to the heaters, as well as 70- to 80 other shuttle systems.
"We know the power is not getting through, so there's a short or a failure in the switching box," said launch director Mike Leinbach.
Installing a new switch and retesting all the systems that draw power through the circuit will take several days. At best, NASA wouldn't be ready to launch Endeavour until May 8, said Mike Moses, who oversees the shuttle launch management team.
Endeavour's six astronauts returned to Johnson Space Center in Houston for additional training before they return for the next launch attempt, Moses said.
Crew family members who had traveled to Florida to watch the launch also returned to Houston, including stricken U.S. Representative Gabrielle Giffords, the wife of Endeavour commander Mark Kelly.
Giffords, an Arizona Democrat, is recovering from a near-fatal shooting in January. She left the Houston hospital where she has been undergoing rehabilitation Wednesday to attend her husband's launch and returned to Houston Sunday, a spokesman from her office said.
Giffords has not been seen publicly since the January 8 attack, which killed six and injured 12 others.
The Endeavour mission is the next-to-last for the 30-year-old shuttle program, which is ending after sister ship Atlantis completes its final voyage this summer.
Endeavour was the replacement ship for Challenger, which was lost in a fatal 1986 launch accident. It is the youngest of NASA's three surviving spaceships and the second to be retired.
Discovery, the fleet leader, returned from its final space mission in March, and Atlantis is due to end the shuttle program with a launch on June 28.