KENNEDY SPACE CENTER, Fla.--Running a month late because of hydrogen leaks and stormy weather, the shuttle Endeavour finally roared to life and blasted off Wednesday on its sixth try, rocketing away through a hazy sky toward a Friday rendezvous with the International Space Station.
Multiple pieces of foam insulation fell from the ship's external tank during the early moments of flight, but it was not immediately clear whether the shuttle's fragile heat shield suffered any significant impact damage.
With commander Mark Polansky and pilot Douglas Hurley at the controls, Endeavour's three main engines ignited in staggered sequence and throttled up to full thrust, followed seconds later by ignition of the shuttle's twin solid-fuel boosters at 6:03:10 p.m. EDT.
Belching fire and churning clouds of exhaust, Endeavour quickly thundered away from launch pad 39A atop twin pillars of 5,000-degree flame from its powerful boosters, rotated about its vertical axis, and arced away to the northeast.
A television camera mounted on the side of the shuttle's external tank provided spectacular views of the Kennedy Space Center launch complex dropping away below and then the separation of the shuttle's twin boosters two minutes and five seconds into the flight.
Several pieces of debris, presumably foam insulation from the tank, ice or both, fell away during the climb out of the lower atmosphere, including some that appeared to hit the orbiter's heat shield well before booster separation. Additional debris events were seen as the shuttle continued its climb out of the discernible atmosphere.
"At about 107 seconds during ascent, we did see some debris events," astronaut Alan Poindexter called the crew from mission control. He said impacts were observed on the underside of the forward part of the right wing, similar to, but less severe than, damage that occurred during a May shuttle launch.
"It appeared to impact the starboard chine area," Poindexter said. "The impact appears to be less than what we experienced on (the last mission) and we'll certainly take a look at this throughout the evening and through the day tomorrow."
"Thanks for the info, I'm sure we'll get a good chance for all of us to get a good look at all that" during post-launch inspections Thursday, Polansky replied. "We can't thank you enough for getting us this far. It was a pretty decent wait, but we're thrilled to be here."
Debris impacts are not an issue after about two-and-a-half minutes, when the shuttle is out of the dense lower atmosphere. But several of the impacts observed during Endeavour's launch occurred during the period when debris strikes are more likely to cause damage.
"If it happened right away, the relative speed of the vehicle's not that great," said Mike Moses, director of shuttle launch integration at the Kennedy Space Center. "And then, once you get out of the atmosphere, if something comes off it kind of stays at the same speed as you when it hits you, so the relative speed is not that great.
"But there's a chunk of time where you're still in the thicker part of the atmosphere where a piece of foam comes off and effectively stops and we fly into it and hit it very fast," he said. "It's not just atmosphere, but that's basically what the phenomenon is."
Debris is not unexpected during launch, but the number of events seen during Endeavour's ascent was unusual. Reporters going through video footage frame by frame counted at least 15 debris events between liftoff and two minutes and 20 seconds into flight.
But Bill Gerstenmaier, chief of space operations at NASA headquarters, cautioned that lighting may have played a role in initial impressions.
"We had very good lighting today, so we probably saw the tank much better than we have on several of the past flights when they were evening launches," he said.
As with all shuttle launchings, engineers will need several days to evaluate launch and on-orbit imagery to make sure there are no problems.
"The bottom line is, we saw some stuff, some of it doesn't concern us, some of it you really just can't speculate on right now," Moses said. "We have the tools and processes to go clear this vehicle for entry. You'll know as we know what we find when we do (the inspections). No real worries there, we've just got to wait and see what happens."
The astronauts plan to spend their second day in orbit Thursday checking out their spacesuits, rendezvous tools and inspecting the shuttle's nose cap and wing leading edge panels using a laser scanner on the end of a 50-foot-long boom attached to Endeavour's robot arm.
If all goes well, Polansky will guide Endeavour to a docking with the International Space Station Friday afternoon. During final approach, the station astronauts, using cameras with powerful telephoto lenses, will photograph the heat shield tiles on the shuttle's belly to look for any signs of damage.
The primary goals of the 16-day mission include attachment of an experiment platform to the Japanese Kibo lab module, replacement of aging solar-array batteries, and delivery of critical spare parts and components, hedges against failures after the shuttle is retired next year.
Five spacewalks by four astronauts will be required, along with carefully choreographed, near-daily use of three robot arms, two on the station and one aboard the space shuttle, to move equipment, spare parts, experiments and spacewalkers from one work site to another.
Complicating the choreography, the station must host a combined crew of 13-- six full-time station astronauts and seven shuttle visitors--for the first time, putting the lab's life support systems, including its new water recycling system, toilets, oxygen generators, and carbon dioxide scrubbers, to the test.
"It's like having your family descend on you for the holidays, right? And they're going to stay for a very long time. And they come, and they're bringing all their stuff," said Mike Moses, chairman of NASA's Mission Management Team, at the Kennedy Space Center.
But he said the combined crews are "more than ready" for the challenge, adding that with six full-time station astronauts on board, "I think what we're going to see is probably some unprecedented efficiencies" because "they know where to go, they know what the procedures are, they know how to get things done."
Polansky, Hurley, and their crewmates -- Canadian flight engineer Julie Payette, David Wolf, Christopher Cassidy, Thomas Marshburn and space station flight engineer Timothy Kopra - had hoped to blast off last month. But the flight was delayed June 13 and 17 by a leaking hydrogen vent line and then three times in a row Saturday, Sunday, and Monday by stormy weather over the Kennedy Space Center.
Electrical storms developed near the space center again early Wednesday, but conditions improved as the afternoon wore on and Endeavour finally was cleared for launch.
The only technical issue Wednesday was concern about the performance of fuel cell No. 3, one of three compact powerplants that combine oxygen and hydrogen to generate the shuttle's electricity. Fresh water is produced as a by-product of the reaction.
Engineers are hopeful fuel cell No. 3 will operate normally throughout the mission, but there is a chance it could have problems at the low power levels required when the shuttle is plugged into the space station's solar power system after docking.
UPDATED at 6:15 p.m. PDT: Adding post-launch news conference; crew informed of debris strikes; NASA managers downplay possible impact damage.