The delay means the space station's returning Expedition 4 crew will extend their U.S. space endurance record from 194 days to at least 195. And given the forecast for Tuesday, Expedition 4 flight engineers Carl Walz and Daniel Bursch might extend their record even further when all is said and done.
In an attempt to improve the shuttle's chances of landing Tuesday, NASA has activated Edwards Air Force Base in California as a secondary touchdown site. The shuttle will have opportunities to land Tuesday at Kennedy Space Center at 11:56 a.m. and 1:32 p.m., and failing that, at Edwards Air Force Base at 3:02 p.m. and 4:38 p.m.
However, the forecast in both places is less than optimal. More rain is expected Tuesday in Florida, while high crosswinds could be a problem in California.
Endeavour has enough on-board supplies to remain in orbit until Thursday.
Bursch, Walz and Onufrienko moved into space station Alpha on Dec. 7, two days after their launch, and moved out as soon as Endeavour arrived with their replacements on June 7. The two American astronauts, both military officers, went on to shatter the U.S. space endurance record of 188 days.
The 194-day mission will be a personal record for Onufrienko, a Russian Air Force colonel whose 1996 mission aboard his country's Mir space station lasted just one day less. A fellow cosmonaut holds the world space endurance record: 438 days.
All three men, who are in their 40s, face weeks of rehabilitation upon their return. Muscles and bones weaken in weightlessness, and the immune system becomes depressed.
The crew exercised each day on the space station to keep their muscles as strong as possible. Bursch, who enjoys running on Earth, got sick of the space station treadmill. "Same run the entire time," he said.
"By any medical standards we have, they're looking superb," said Dr. Terry Taddeo, a NASA flight surgeon. But he warned they will almost certainly feel nauseated and wobbly, at least at first.
While Endeavour was docked to Alpha, two shuttle astronauts performed three spacewalks to replace a wrist joint on the space station's 58-foot robot arm, install a movable platform for the arm and do other work.