CAPE CANAVERAL, Fla. -- Endeavour's final blastoff is set for 8:56 a.m. next Monday, while the last shuttle mission -- by Atlantis -- is likely to slip to mid-July, NASA officials said Monday.
Endeavour is back on track for launch after about 10 days of troubleshooting and repairs that followed a scrubbed attempt April 29.
Although managers haven't pinpointed the exact cause of an electrical short that kept a set of fuel line heaters from turning on, they're confident they've taken the steps necessary to prevent a repeat failure.
"We know we have really good power heading out to those heaters," said Mike Moses, the shuttle launch integration manager. "We have very high confidence that nothing's going to happen."
Six Endeavour astronauts led by mission commander Mark Kelly, whose wife, U.S. Rep. Gabrielle Giffords, continues to recover from a gunshot wound to the head, plan to jet back to Kennedy Space Center around 11 a.m. Thursday, and a three-day countdown will pick up at 7 a.m. Friday.
The delay in the 16-day mission to the International Space Station has pushed back the timing of Atlantis' launch, which had been targeted for June 28.
NASA won't set a new target date until after Endeavour is off the ground, but the second week of July is now the approximate timeframe -- squashing speculation that the launch would be timed to the July 4 holiday.
"We'll be looking past July 4 before we're ready to launch," said Moses.
The delay likely means a couple extra weeks of work for thousands of shuttle contractors whose jobs are set to end after Atlantis returns home and the shuttle program is retired.
Most of those layoffs were planned for mid- or late-July based on a June 28 launch, but will push back along with the mission to ensure the necessary personnel are in place.
Still, lead shuttle contractor United Space Alliance plans to send out 60-day notices this week alerting employees they are candidates for layoff when the time comes.
During the Mother's Day weekend, teams worked around the clock to complete repairs and tests to verify Endeavour's fuel line heaters were back up and running.
In the back end of the orbiter at launch pad 39A, shuttle electricians routed roughly 20 feet of new wiring between the heaters and a power distribution box, bypassing suspect wires.
The briefcase-sized box and some thermostats were also replaced after the failure, so managers believe they've eliminated the potential causes of the electrical problem and have sufficient rationale to proceed with a launch.
Recently reviewed data suggested the culprit might be a current spike during a thermostat test last June, an issue the new wiring would have resolved.
"Endeavour's looking good," said Mike Leinbach, the shuttle launch director. "Hopefully, this time the heaters will work and we'll be able to launch on time next Monday."