HOUSTON — After a week and a half of intense and unprecedented work, the astronauts aboard shuttle Discovery undocked from the international space station on Monday to begin their two-day journey home.

"Thank you guys for the module and all your help," space station commander Peggy Whitson said as Discovery pulled away from the orbiting outpost.

Discovery's crew arrived at the station on Oct. 25 and quickly accomplished the ambitious tasks of moving a massive solar power tower and installing the module, a school bus-sized compartment that will serve as a docking port for future laboratories.

But their toughest assignment emerged when one of the newly installed tower's wings ripped in two places as it was being unfurled.

Fearing the damage could worsen and the wing could be ruined, NASA sent a spacewalking astronaut far from the safety of the station to make emergency repairs on what amounted to a live electrical generator.

Saturday's history-making spacewalk has allowed the space agency to push forward with plans to launch the shuttle Atlantis and its major cargo — a new European lab — in December.

Shortly after undocking, the shuttle flew a full lap around the station, primarily so crew members could take pictures of the outpost's new configuration. Engineers were particularly interested in seeing how the newly mended solar wing was affected by the vibrations of undocking.

Computer problems forced pilot George Zamka to navigate the loop without help from software that provides information about the shuttle's path. But Discovery commander Pamela Melroy and Mission Control said he did a perfect job.

"We would never know that he doesn't have the data. It looks great," Mission Control said.

Astronaut Daniel Tani, who flew to the station aboard Discovery and will remain in orbit for two months, radioed the shuttle crew a last goodbye as they finished circling the outpost.

"I miss you already," he said. "Fly safe. Get home safe. I'll see you on the ground."

"Yep, we'll see you on the ground," Melroy replied.

Later, the crew planned to take another close-up laser survey of Discovery's wings and nose cap, this time to check for any possible micrometeroid damage. Inspections conducted earlier in the mission found no evidence of significant damage from debris shed during liftoff.

Discovery is scheduled to land Wednesday afternoon.

Whitson and Melroy are the first women to simultaneously manage two spacecraft in the 50-year history of spaceflight.

Whitson and her crew plan to move the compartment, named Harmony, to its permanent location next week.


On the Net:

NASA: spaceflight.nasa.gov/