ORLANDO, Fla. -- The space shuttle Endeavour got a green light Monday to launch on 8:56 a.m. EDT on May 16, even though NASA is not certain about the root cause of an electrical failure that scrubbed the April 29 launch attempt.
NASA mission management team chairman Mike Moses said NASA officials have "full confidence" that they have isolated the problem to a switch box, or to some wiring, and both have been replaced.
Tests of the new switchbox and wiring found everything working fine, Moses said.
This will be the final mission for Endeavour, its 25th, before it is retired. It will be commanded by Navy Capt. Mark Kelly. His wife, U.S. Rep. Gabrielle Giffords, D-Ariz., intends to attend the launch at Kennedy Space Center. Giffords, who was shot in an attack in January, came to Florida for the April 29 attempt but had to leave when it was scrubbed.
Kelly and the other five astronauts are expected to return to the space center on Wednesday.
However, engineers and technicians still have not figured out why there was a failure in the first place in the switchbox, a complex piece of electronic hardware with numerous circuits. Those tests continue.
Moses and launch director Mike Leinbach announced at a press briefing Monday afternoon that everything appears clear.
"We don't exactly have the root cause," Moses said. "But we have full confidence that we have removed the source of the failure."
The delayed launch of Endeavour means there will be a delay in the next and last launch in the space shuttle program, that of Atlantis. That shuttle was targeted to launch on June 28 but Endeavour's launch schedule is beginning to conflict with Atlantis's pre-launch schedule.
Moses and Leinbach said they do not know when Atlantis would launch and would not make that decision until later. Most likely is the second week in July, Moses said.
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