The shuttle Endeavour is poised for blastoff Saturday on one of the most complex space station assembly missions yet attempted, a grueling 16-day flight to attach a Japanese experiment platform, deliver critical spare parts, replace massive solar array batteries, and swap out a station crew member.
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."
For the Endeavour astronauts, shuttle mission STS-127 is the equivalent of a "heavy duty construction mission," said flight engineer Julie Payette, a Canadian astronaut, jet pilot, and robot arm operator. "It is about as complex a mission as we've put together so far in the joint shuttle-space station program."
"With the shuttle program ending in 2010, we had to pack the mission as much as we could. So our mission is probably reaching the limits of what one crew can do on a 16-day mission: five different spacewalks, we're basically operating at least two (robot) arms every day of the mission except for one, it is extremely intensive in the choreography that we do.
"But it is a construction mission," said Payette, making her second shuttle flight. "We are crane operators, we're construction workers, we're going to replace elements of the station, install new elements on the station, transfer equipment inside the station, we're going to disturb life for two weeks, and then we're going to go home."
Endeavour is scheduled for liftoff on the 127th shuttle mission at 7:17:15 a.m. EDT Saturday, roughly the moment Earth's rotation carries launch pad 39A into the plane of the space station's orbit.
Joining Payette on the shuttle's upper flight deck will be veteran commander Mark Polansky, making his third flight, rookie pilot Douglas Hurley, and first-time flier Christopher Cassidy, a Navy SEAL with combat experience in the caves of Afghanistan. Based on seat positions, Hurley will be the 499th individual to reach orbit and Cassidy will be the 500th.
Strapped in on the lower deck will be David Wolf, a doctor making his fourth flight, physician-astronaut Thomas Marshburn, and space station flight engineer Timothy Kopra, both making their first flights.
Kopra, an Army helicopter pilot, will trade places with Japanese astronaut Koichi Wakata as a member of the Expedition 20 crew, remaining behind aboard the International Space Station when Endeavour departs. Wakata, launched to the station in March aboard the shuttle Discovery, will take Kopra's place aboard the shuttle for the trip back to Earth.
Along with the crew swap, the primary goals of the mission are to attach a porch-like external experiment platform to the Japanese Kibo laboratory module, to equip it with three experiment packages, and to hook up TV cameras, data and electrical connections. Attachment of the Japanese Exposed Facility, or JEF, will complete the assembly of the station's most sophisticated laboratory suite.
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.
"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."
Protecting against failures down the road, the astronauts also plan to mount a spare S-band antenna assembly on an external storage platform, along with a spare cooling system pump module and a replacement drive unit for the station's robot arm transporter.
In one of the more challenging tasks faced by the spacewalkers, six 375-pound batteries will be replaced in the station's oldest set of solar arrays on the far left end of the lab's main power truss. The battery replacement will be spread over two spacewalks.
"The P6 batteries have been up there since December of 2000," said Kirk Shireman, deputy director of the space station program at the Johnson Space Center. "They're reaching the end of their life (and) we need to swap them out. We'll be doing that for the first time, it's very challenging."
The spacewalkers also will attempt to rewire a gyroscope circuit, install another television camera to provide additional external views, and deploy a jammed external storage mount on the left side of the power truss. The crew plans to deploy two others on the right side of the station that are needed to hold spare parts and equipment being stockpiled as the shuttle program winds down toward retirement in 2010.
Finally, the astronauts will make preparations for the debut flight of a Japanese cargo ship in September. The HTV spacecraft is designed to be plucked out of open space by the station's robot arm for docking to the Harmony module's upper port.
Wolf and Kopra will carry out the mission's first spacewalk, followed by EVAs with Wolf and Marshburn, Wolf and Cassidy and then a final two excursions by Cassidy and Marshburn. Polansky, Hurley and Payette will operate the shuttle and station robot arms, moving from the orbiter to the station and back as needed, assisted by Wakata.
"It's an extremely challenging, complex mission," Polansky told CBS News. "The robotics that are interlaced with the spacewalks are complicated, we do complicated robotics every single day of the mission, starting with the first full day in orbit all the way through. We just never get to come up for air. It's something I think about a lot."
And with a combined crew of 13 aboard the space station, the pace will be hectic to say the least.
"It'll be very interesting to see how we're going to adapt to that many people inside a relatively small vehicle," Payette said. "I mean, it's very roomy compared to the comfort of the space shuttle, but it's still a very confined environment. There will be growing pains, how to adapt to one another, not to step on one another, not to all speak on the communications loops at the same time.
"But I think it'll be awesome for the first time to have that many people in space. It will really be the beginning of a permanent settlement in space, because that's what it will be in the future and we're trying it out for the first time. It'll be very interesting, the social aspects of having that many people on board from different nationalities."
Assuming an on-time launch, Endeavour will dock with the space station around 3:55 a.m. on Monday. The mission will be conducted during the deep overnight hours in the United States, with the five spacewalks beginning between 1:42 a.m. and 10:12 p.m. on June 16, 18, 20, 21 and 24. Undocking is expected around 8:11 p.m. on June 26 with landing back at the Kennedy Space Center scheduled for 12:18 a.m. on June 29.
"I sum it up this way," Payette said. "Six people, five EVAs, three (robot) arms, seven (payload) handoffs, 16 days. It is going to be an action-packed flight. So if you're bored, please tune in."