NASA unanimously approved a Monday morning launch attempt for the space shuttle Endeavour, after reviewing all the repairs for an electrical problem that grounded the next-to-last shuttle flight two weeks ago.
The flight to the International Space Station will be led by Commander Mark Kelly, the husband of U.S. Rep. Gabrielle Giffords, who was critically wounded during a January shooting rampage in her Tucson, Ariz., district. She was present for the first launch attempt, and is to be on hand for this one as well.
Mission management team chairman Mike Moses said Saturday he is confident the repairs took care of the electrical short and blown fuse that prevented a string of heaters from turning on during the first launch attempt on April 29. A thermostat with an exposed wire was replaced, as was a switch box with a blown fuse.
"In our minds, we are good to go," Moses told reporters.
Forecasters put the odds of good weather at 70 per cent. The main concerns are stiff crosswinds and low clouds.
"Looks like we r flying!!!" astronaut Mike Fincke said in a Twitter update late Saturday afternoon.
Launch director Mike Leinbach said an estimated 500,000 spectators are expected to jam area roads and communities in advance of Monday's scheduled 8:56 a.m. ET launch. That's more than the crowd for Discovery's final launch in February, but far short of what was anticipated for Endeavour's launch attempt on April 29.
"They're not quite expecting that big surge … but still it will be a heck of a traffic jam," Leinbach said. Because of the clogged roads, NASA may opt for a two-day delay rather than the usual one day, if Monday's try is called off in the final few hours of the countdown. Launch controllers need to be able to get home and rest, he said.
U.S. President Barack Obama and his family were among those who travelled to Kennedy Space Center last month hoping to see a launch. He met with the astronauts and visited with Giffords, but won't return Monday.
"I sure would have liked to have him come back," Leinbach said. "We did all that work for him, and now he's not going to get to see a launch." It's possible, he noted, that the president may come for the very last shuttle launch in July.
Leinbach is thrilled that Giffords will be present for the launch. As before, the congresswoman will remain off-limits to the public and even most space centre employees. Five other members of Congress also will attend.
"It will be a terrific time for her," Leinbach said, "and Mark just can't wait to see her back here. That's good stuff."
The congresswoman has been undergoing rehabilitation in Houston, her husband's home base, for a gunshot wound to the head.
Kelly and five other veteran spacemen are assigned to the 16-day flight. They will deliver a $2-billion US particle physics detector — a project led by a Nobel Prize-winning physicist — as well as critical space station spare parts.
Atlantis will close out the 30-year space shuttle program with a July flight.
As the program winds down, layoff notices went out last week to nearly 2,000 shuttle contract workers at NASA's launch site. They will lose their jobs this summer, once Atlantis takes flight for the last time.
Leinbach said the timing of those notices is unfortunate, coming right in the middle of a launch countdown.
"The mood is a little bit downcast right now," he said. "But … I have no worries at all about the team being able to make the right calls on Monday."