Space Shuttle Endeavour to Launch Tonight

The space shuttle Endeavour sits poised atop its Launch Pad 39A for a March 11, 2008 launch. CREDIT: NASA/Amanda Diller.

CAPE CANAVERAL, Fla. — NASA's space shuttle Endeavour is on track to light the predawn Florida sky ablaze early Tuesday as it rockets toward the International Space Station (ISS) with seven astronauts on board.

Led by commander Dominic Gorie, Endeavour's STS-123 crew will install the first piece of Japan's three-part Kibo laboratory, assemble a monstrous, two-armed Canadian robot and deliver a suite of on-orbit experiments during their mission. The shuttle is counting down toward a planned 2:28 a.m. EDT (0628 GMT) launch on Tuesday from NASA’s Kennedy Space Center in Cape Canaveral, Fla.

Gorie and his crew plan to spend 16 days executing their mission, which is the longest space station-bound flight NASA has ever concocted. And with no less than five spacewalks on tap, the astronauts consider their mission as one of the most intense and exhilarating, too.

"If you go to a drawing board and describe an exciting mission from scratch, I think you'd end up with STS-123," Gorie said. "We've got everything on this mission that you could imagine."

Joining the veteran spaceflyer aboard Endeavour will be pilot Gregory H. Johnson, mission specialists Robert Behnken, Mike Foreman, Rick Linnehan and JAXA astronaut Takao Doi. Rookie spaceflyer Garrett Reisman will stay behind as a member of the Expedition 16 space station crew, allowing European Space Agency (ESA) astronaut Leopold Eyharts to return home.

A successful launch will mark the second space station assembly mission of 2008, as well as the second of up to six NASA shuttle missions planned for the year.

Clear skies?

Endeavour has a 90 percent chance of favorable weather conditions at launch time, with the potential for thick clouds posing the only threat, said U.S. Air Force Lt. Col. Pat Barrett, NASA’s shuttle weather officer with the 45th Weather Squadron, in a Sunday briefing.

"We are expecting favorable conditions for launch. The only concern we have is a slight chance of seeing some low-level clouds moving into the area from … the Atlantic," Barrett said, adding that cloud cover can interfere with tracking the 100-ton orbiter as it speeds to more than 17,500 mph (28,200 kph) during the trip to space.

If all goes as planned, Endeavour will be the second shuttle to launch in darkness since the 2003 Columbia tragedy, and the 30th total night launch, following the shuttle Discovery's December 2006 liftoff.

Shot in the dark

Darkness can be dangerous because technicians have a tough time spotting errant chunks of ice or insulating foam that can shed from an orbiter's 15-story fuel tank — debris which can damage the heat-resistant underbelly of a space shuttle.

But LeRoy Cain, chair of NASA's mission management team, said the agency has addressed these risks by improving the external fuel tank and adding extra cameras to the launch vehicle.

"We feel very comfortable to go fly at night," Cain told reporters during a Sunday briefing. One of the new improvements flying aboard Endeavour is a flash unit for a belly-mounted camera to help photograph the shuttle’s fuel tank after separation.

"This will be the first time that we've flown that," Cain said, noting that it should put on quite a show when Endeavour sheds its orange fuel tank high above the Earth. "You can expect to see some pretty brilliant flashes in a sequence [in video footage] after we have physical separation from the external tank."

International cargo

Shortly after reaching the space station some 212 miles (340 kilometers) above the Earth, the crew will deliver the cylindrical Japanese Logistics Pressurized (JLP) module.

"Japanese people have been waiting a very long, long time," Yoshiyuki Hasegawa, ISS program manager for JAXA, said of the JLP's launch and delivery to the space station. "It will be an unforgettable event."

Two days after Japan's first orbital room is stowed in a temporary berth at the space station, spacewalkers Linnehan, Foreman and Behnken will piece together Dextre — the Canadian Space Agency's (CSA) maintenance robot that weighs more than 3,440 pounds (1,560 kilograms).

The giant robot, often personified by the STS-123 crew as "Mr. Dextre," will have an arm span of about 30 feet (9 meters) and stand 12 feet (3.7 meters) tall. By guiding highly precise "hands" from inside the space station, astronauts can perform basic space station maintenance without having to venture into the unforgiving space environment outside.

"As spacewalkers, we don't want to put ourselves out of the job," Foreman said of the robot's abilities. "But I think … Dextre will be a boon to the space station when it gets built and put into work."

If the shuttle's Tuesday morning launch attempt is foiled, NASA will try again no earlier than 2:02 a.m. EDT (0602 GMT) on Wednesday with a less encouraging 70 percent chance of liftoff. Clouds may botch a second attempt, with the added threat of rain showers, shuttle weather officials said. Should further delay be required, Endeavour would stand down until after March 15 to allow an unmanned Delta 2 rocket to launch a navigation satellite from the nearby Cape Canaveral Air Force Station.

Endeavour is scheduled to return to Earth on March 26 at 8:35 p.m. EDT (0035 GMT March 27) at Kennedy Space Center.

NASA will broadcast the launch of Atlantis' STS-123 mission live on NASA TV beginning at 9:30 p.m. EDT (0130 March 11 GMT). Click here for SPACE.com's STS-123 mission coverage and NASA TV feed.

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