Shuttle Discovery Undocks From Space Station
This still image from a video camera outside the shuttle Discovery captures the space station and its new Kibo lab (right with attic and robotic arm) after undocking on June 11, 2008 during NASA's STS-124 mission.
Credit: NASA TV.

This report was updated at 6:01 p.m. EDT.

HOUSTON — NASA?s shuttle Discovery and its seven-astronaut crew said ?sayonara? to the International Space Station (ISS) Wednesday to begin the trip home after delivering a new Japanese lab to the orbiting outpost.

Discovery undocked from the space station at 7:42 a.m. EDT (1142 GMT) after nine days of orbital construction to install and outfit Japan?s billion-dollar Kibo laboratory.

?We wish them the best with their expedition and we hope we left them a better, more capable space station than when we arrived,? Kelly said of the station?s three-man crew, saying goodbye after delivering Japan?s Kibo lab. ?Sayonara.?

Discovery cast off from the station as the two spacecraft flew 214 miles (344 km) above the southern Pacific Ocean, just east of Australia. The spacecraft is due to land Saturday with Kelly, shuttle pilot Ken Ham and mission specialists Karen Nyberg, Ronald Garan, Michael Fossum, Japanese astronaut Akihiko Hoshide and returning station crew member Garrett Reisman of NASA.

Reisman is returning to Earth after three months in space after turning his flight engineer reins over U.S. astronaut Gregory Chamitoff, who launched aboard Discovery May 31 and remained aboard the station today with two Russian crewmates.

?It was a great adventure with all of you, an adventure of a lifetime,? said Chamitoff, who is beginning a six-month mission at the station. ?We wish you guys a terrific flight back, an awesome landing and look forward to seeing you on the ground.?

Reisman told the station crew to feel free to dig into the stash of Snickers candy bars he left behind, but was apparently too late.

?We found those last night and have already broken into them,? Chamitoff said.

Space station?s new ?hope?

During their nine days at the space station, Discovery installed Japan?s Kibo lab, added a storage room to the rooftop of the 37-foot (11-meter) module and test drove the massive room?s new robotic arm. Three spacewalks were performed during the mission.

?This mission has gone just phenomenally well so far,? said Matt Abbott, NASA?s lead shuttle flight director for Discovery?s flight, during a Tuesday briefing here at the Johnson Space Center.

Built by the Japan Aerospace Exploration Agency (JAXA), the Kibo lab is the largest room aboard the space station and leaves the orbiting outpost about 71 percent complete, NASA officials said.?It has two windows and its own small airlock to provide access to an external experiment platform that is slated to launch aboard a NASA shuttle next year.

Astronauts delivered Kibo?s small storage room earlier this year during a March shuttle flight. A smaller robotic arm, which will allow Kibo?s main 33-foot (10-meter) limb to manipulate experiments on the external platform, is also slated to fly next year.

?I?m looking at the next chance for our science work,? said JAXA?s deputy Kibo operations manager Tetsuro Yokoyama, adding that first experiments aboard the new lab are expected to begin in August.

A closer look

Before departing the station, shuttle pilot Ken Ham took the helm of Discovery to guide it through a victory lap of sorts around the orbiting lab while his crewmates snapped photographs of its exterior.

Known as a fly-around, the maneuver allows astronauts to document changes in the station?s appearance while giving shuttle pilots a change to fly their spacecraft.

?This is a great tradition that started somewhere back in the early days of rendezvous-type missions with the space shuttle,? Ham told reporters before flight. ?And whoever thought of it was brilliant.?

Discovery?s crew also conducted a five-hour inspection of the heat shield panels along their shuttle?s wing edges and nose cap. The inspections are now standard since heat shield damage led to the loss of the shuttle Columbia and its astronaut crew in 2003.

Discovery launched without its own laser-tipped boom for heat shield inspections just after liftoff and before landing because Japan?s massive Kibo lab took up too much room in cargo bay. Instead, astronauts retrieved an inspection boom left at the station during a preview shuttle mission.

Abbott said that a cursory inspection of Discovery using the limited reach of its own robotic arm, as well as photographs of its heat shield taken before docking, have shown no areas of concern for engineers back on Earth.

Today?s scan will provide a better view of the underside of Discovery?s wing edges, with engineers hoping to complete their analysis some time tomorrow, Abbott said.

Meanwhile, Discovery?s crew is on track for its planned Saturday landing at NASA?s Kennedy Space Center in Cape Canaveral, Fla.

Mission Control here roused the astronauts early Wednesday with the song ?Centerfield? by John Fogerty, a tune selected for Ham by his wife Michelle.

?Girl, you are my home, and all of us are going to start our journey home today,? Ham told his wife via Mission Control as the shuttle and space station zipped around the planet at 17,500 mph (28,163 kph). ?From my rough calculations, that?s about a million miles, but we?re going really fast so we?re on our way.?

NASA is broadcasting the Discovery's STS-124 mission live on NASA TV on Saturday. Click here for SPACE.com's shuttle mission updates and NASA TV feed.