JOHNSON SPACE CENTER, Houston--Combining robotics with a five-hour 32-minute spacewalk, the Endeavour astronauts accomplished the primary goal of their space station assembly mission Saturday, successfully attaching a sophisticated experiment platform to the Japanese Kibo laboratory module.
In the first of five planned spacewalks, astronauts Dave Wolf and Tim Kopra prepped the Japanese Exposed Facility, or JEF, for removal from the shuttle's cargo bay and then went on to other tasks, including the successful deployment of a jammed external storage system.
Koichi Wakata and Douglas Hurley, meanwhile, operating the space station's robot arm, pulled the JEF platform out of the shuttle's payload bay and handed it off to Julie Payette, operating Endeavour's robot arm. After repositioning the station crane, Wakata re-grappled the JEF and moved it into position for attachment to the Kibo module.
The Kibo complex is made up of two modules, a roomy central lab and an attached logistics module. The main Japanese lab module is equipped with its own airlock and its own robot arm to move experiments out to the exposed facility and back inside as needed. Experiment packages launched aboard Endeavour will be attached to the JEF later in the mission.
"The Japanese Exposed Facility, or JEF as we tend to call it, is very impressive," Wolf said in a NASA interview. "It's a large external porch to the space station where high quality experiments can be conducted in the high vacuum of space. It's really an exceptionally valuable piece of real estate. It has its own robotic arm, the ability to do observations of the Earth and of the sky, astrophysics experiments, a very wide range of abilities."
The exposed facility was locked onto the Kibo lab module at 6:29 p.m. CDT, about an hour and a half after Wolf and Kopra completed their spacewalk.
"To me, it's more than 20 years (of) effort," said Tetsuro Yokoyama, deputy manager of the Kibo project. "It was a very distant achievement then. But now, it's an hour or so (until activation). So it's very emotional for me as well as our team."
Said space station Flight Director Holly Ridings: "Today is a great day for spaceflight."
"We did an EVA (spacewalk) and we did robotics, we did some exciting operations with our Japanese international partners," she said. "We've got 13 people on board Endeavour and the International Space Station combined. So when you do all those things simultaneously and it all works out as well as it did today, it is a great day in spaceflight."
NASA's Debris Analysis Team, meanwhile, is in the final stages of reviewing launch and on-orbit photography of the shuttle Endeavour's heat shield.
The ship's nose cap and wing leading edge panels have been cleared for entry as is and while 16 areas have been identified with minor tile damage, engineers have not seen anything that warrants repairs or additional inspections
Mike Moses, acting as chairman of NASA's Mission Management Team, said the debris team recommended Friday evening to forgo any additional "focused" inspections after examining hundreds of photos shot during Endeavour's approach to the station Friday.
"After the review they decided they did not need that additional data, which is a very good sign," Moses said. "We have not yet officially cleared the vehicle for entry, but having no focused inspection is a step down the path of saying we are going to be in really good shape."
Video from cameras mounted in the shuttle's twin-solid fuel boosters should be available for analysis by Sunday. Engineers are eager to examine the footage to better understand what caused an unusual amount of foam insulation to peel away from the central "intertank" area of the external tank during Endeavour's launch.
The major concern during ascent is debris that comes off in the first two minutes and 15 seconds of flight, when the shuttle is still in the dense lower atmosphere. During that period, lightweight pieces of foam can slow down so fast in the airstream that the shuttle can run into them at a high enough relative velocity to cause heat shield damage.
During Endeavour's launching, most of the intertank foam that fell away was released after the period of aerodynamic vulnerability. But Moses said the mechanism is unknown and until engineers get a better understanding, they can't rule out the possibility the next tank in the sequence could shed foam earlier.
"We aren't ready yet to say we're good and that we don't have a mechanism that would say it can't come off early," he said. "That's one of the big question marks we're going to have to answer as part of our flight rationale to be ready to fly the (next) tank, ET-132."
External tank No. 132 currently is attached to a set of boosters at the Kennedy Space Center awaiting the shuttle Discovery and rollout to the pad for launch in late August. NASA originally planned to move Discovery to the Vehicle Assembly Building for attachment to the tank Monday, but the move is now on hold.
"One of the things we're going to do is go do pull tests on that tank," Moses said. "They're basically going to go cut inch-diameter-size core samples and hook up a load cell to it and pull to see do we have a good bond to the metal primer underneath or not?"
Complicating the picture, foam apparently came off Endeavour's tank after it had separated from the shuttle, "yet another puzzling type mechanism," Moses said. "It's puzzling enough that foam's popping off so late without a lot of aerodynamic forces. It probably means it's thermally related, but again, we're starting to speculate."
Engineers at Lockheed Martin's Michoud Assembly Facility where the tanks are built are "looking at all that data, trying to find a common thread here that allows us to determine what that mechanism is and then based on that, do we have assurance that it can't come off earlier than that?" Moses said. "And that's really going to be the linchpin of our flight rationale."