The U.S. space shuttle Discovery has landed in Florida with three international space station crew members returning from nearly six months in orbit. The trio faces extensive reconditioning to gravity.
Discovery touched down at the Kennedy Space Center to a greeting from Mission Control. Inside the orbiter were former station commander Yuri Usachev and his two U.S. astronaut colleagues, Susan Helms and Jim Voss.
"Welcome home to all of you, especially Yuri, Susan, and Jim. It's great to have you back on Earth," said the mission controller.
The landing ended a 12-day mission in which Discovery exchanged the three with a replacement crew.
Their ride back has put them under gravity's pull for the first time in almost half a year. U.S. space agency flight surgeon Terry Taddeo says they face weeks of physical rehabilitation to sharpen their sense of balance and strengthen muscles and bones, which weaken in prolonged weightlessness.
"It varies from individual to individual, but generally people don't feel like their own selves again and exercise like they could until, really, several weeks or months out," he said. "Again, it depends on the individual."
After a flurry of frequent missions to the outpost over the past year, the next shuttle visit will not occur until early December when Endeavour brings up another crew to relieve the one that just took over. This is the longest gap in shuttle visits since station occupation began last November.
But station operations official Jim Van Laak says the U.S. space agency has planned for the interim by stocking the outpost thoroughly during Discovery's mission. It has also arranged for emergency parts that might be needed to fly up on Russian rockets scheduled to dock with the station over the next few months.
"We have a process we go through to consider reasonable failure cases and, of course, we plan for our logistics verycarefully," he said. "It would be unwise, probably, to say that we have no concerns about so long a time before the shuttle will be able to come back. But we've thought about it for a long time, we've prepared for it well. We're in good shape."
Aboard the space station, an empty Russian supply rocket has undocked to make room for a loaded one scheduled to arrive early Thursday.