Thisstory was updated at 8:47 a.m. EDT.
HOUSTON —The seven astronauts of NASA?s shuttle Discovery will say farewell to theInternational Space Station (ISS) crew Tuesday as they prepare to head homeafter adding a massive Japanese laboratory to the orbiting outpost.
Shuttlecommander Mark Kelly and his crew will shut the hatches between Discovery andthe station at about 3:57 p.m. EDT (1957 GMT) after nine days of constructionwork to deliver Japan?s billion-dollar Kibo laboratory.
?TheJapanese laboratory is big, capable, pretty much ready to go,? Kelly said fromorbit Monday. ?It?s in good shape.?
The shuttlecrew will take a few hours off today before shutting the hatches betweenthe station and their spacecraft. Discovery is set to undock from the spacestation Wednesday at 7:42 a.m. EDT (1142 GMT).
Discoveryastronauts delivered Japan?s tour bus-sized Kibo laboratory and attached its rooftopstorage attic last week. The astronauts performed three spacewalks to primethe new lab and its 33-foot (10-meter) robotic arm for orbital work.
?It?ssimply spectacular to see the Kibo robotic arm partly deployed,? said Tetsuro Yokoyama,deputy Kibo operations project manager for the Japan Aerospace ExplorationAgency, which built the new 37-foot (11-meter) lab.
The nearly16-ton Kibo lab?s arrival boosted the station?s mass to more than 600,000pounds (277,598 kg), leaving it about 71 percent complete, NASA officials havesaid. A smaller robotic arm and porch-like external experiment platform areexpected to completethe Kibo lab when they launch next year, but JAXA officials are hoping tobegin the first science experiments as early as August, Yokoyama said.
?Of course,the opportunity to do science research grew incredibly now that we have anadditional science module,? said station commander Sergei Volkov of Russia. ?It?s great,and we are looking forward to doing this.?
In additionto the Kibo module, Discovery also ferried NASA astronaut Gregory Chamitoff tothe space station. He replaced fellow U.S. spaceflyer Garrett Reisman, who haslived aboard the station for the last three months.
?I can?timagine what these past few months would have been like without the help you?vegiven me,? Reisman told mission controllers here inHouston, as well as at all the station?s centers in the U.S., Canada, Russia,Europe and Japan.
Reisman joined the station's Expedition 16 crew in March and stayed aboard in April when his Expedition 17 crewmates, Volkov and cosmonaut Oleg Kononenko, arrived.
"Garrett, best wishes to you as you spend the last day of your mission on the space station," Mission Control radioed up Reisman during his last morning briefing. "Thanks for all your hard work over the last several months, we all look forward to your return."
Chamitoffis settling in for a six-month stay aboard the station as part of its three-mancrew, while Reisman will return to Earth aboard Discovery.
?When theyleave, I think it?s going to be very sad for me to see them go,? Chamitoff saidMonday. ?I think that one moment, when we close the hatch, that?s going to bethe hard moment.?
Discoveryand itsastronaut crew are scheduled to land at NASA?s Kennedy Space Center inFlorida on Saturday.
NASA is broadcasting Discovery's STS-124 mission live onNASA TV on Saturday. Click herefor SPACE.com's shuttle mission updates and NASA TV feed.
