CAPE CANAVERAL, Fla. - Seven astronauts are set to blast off on the space shuttle Endeavour Saturday morning on an ambitious mission bound for the International Space Station.
The shuttle is scheduled to lift off at 7:17 a.m. EDT (1117 GMT) from the seaside Launch Pad 39A here at NASA's Kennedy Space Center. Endeavour is slated for a grueling 16-day mission to ferry the final element of the space station's Japanese-built Kibo laboratory.
"We all realize that we have a tremendous amount of work to do," said Endeavour commander Mark Polansky. "We do know it's a combination of a sprint and a marathon, because it's a long, long mission."
The weather outlook is good for Saturday's planned liftoff, with a 90 percent chance of favorable conditions for launch, shuttle weather officer Kathy Winters said. Ground crews plan to begin filling the shuttle's tall orange fuel tank with its liquid oxygen and liquid hydrogen propellant Friday at 10:02 p.m. EDT (0202 GMT).
The addition to Kibo (which means "Hope" in Japanese) is an outdoor porch-like platform that will house science experiments exposed to the space environment. When this element is installed, the $1 billion laboratory, Japan's major contribution to the space station, will be finished.
"A lot of Japanese people are paying attention to this flight because Kibo is the first manned space facility in Japan and this will be completed by this flight," said Koki Oikawa, a member of the Kibo project team at the Japanese Aerospace Exploration Agency (JAXA).
Endeavour's STS-127 crew plans a series of five tricky spacewalks and complex robotic arm maneuvers to install the new porch, as well as a host of spare supplies and equipment for the orbiting laboratory.
The mission will also make another important delivery: rookie NASA astronaut Tim Kopra, who will stay behind on the station after the shuttle leaves for a long-duration stint as an Expedition 20 flight engineer. Kopra will replace JAXA astronaut Koichi Wakata, who is finishing up a three-month stay on the space station, and will ride home along with the STS-127 crew on Endeavour.
"The thing that I'm excited about is being able to fulfill the last several years of training and to do my small part to help out the advancement of science and space exploration," Kopra said in a NASA interview.
Along with Kopra and Polansky, NASA astronauts Doug Hurley, Chris Cassidy, Tom Marshburn, Dave Wolf, and Canadian Space Agency astronaut Julie Payette will ride aboard Endeavour.
When the shuttle's seven crewmembers arrive at the space station they will boost the total population there to 13 — a record high. The station recently began hosting six-person crews, doubled from the previous three-person crews, and Endeavour will be the first shuttle to visit the newly crowded lab.
"Oh, I think it's going to be a bit of chaos," Hurley said in a preflight interview. "Everybody's kind of expecting that to be a little bit crazy when we first get there and before everybody gets everything sorted out. But by the same token, that's what we've all been working towards for many years is to get the ISS up to this six-person capability, so I think it'll be helpful in many ways because that's three more sets of hands that you have to help out."
The space station is currently home to two Russians, and one astronaut each from the United States, Japan, Belgium and Canada. When Endeavour lifts off, it will be the first time in history two Canadians - Payette and station astronaut Robert Thirsk - are in space at the same time.
Endeavour's STS-127 mission is NASA's third shuttle fight of the year and the 127th mission for the three-orbiter fleet. It is Endeavour's 23rd mission to space.
If the shuttle is unable to launch Saturday as planned, NASA can try again June 14 or June 15. The weather outlook for those days is also promising. There is a 90 percent chance of good weather if there is a 24 hour delay, and an 80 percent chance of favorable conditions for a 48 hour postponement.
After June 15, Endeavour must stand down to allow two unmanned lunar spacecraft to launch toward the moon from the nearby Cape Canaveral Air Force Station. The next chance for the space shuttle to launch is July 11, when sunlight and heating conditions at the space station are favorable again.
SPACE.com is providing continuous coverage of STS-127 with reporter Clara Moskowitz at Cape Canaveral and senior editor Tariq Malik in New York. Click here for mission updates and SPACE.com's live NASA TV video feed. Live launch coverage begins at 2:00 a.m. EDT (0600 GMT).