SPACE CENTER, Houston -- After orbiting the Earth for nearly two weeks, astronauts aboard space shuttle Discovery were told to circle the planet for another day as bad weather in Florida forced NASA to delay Monday's scheduled landing.
The astronauts had powered up their spacecraft and were awaiting word from Mission Control to fire their braking rockets and head for home when controllers announced early Monday that low clouds over Cape Canaveral would postpone the landing.
When clouds still threatened after the second of two opportunities, NASA officials rescheduled the landing for Tuesday.
"We just can't get comfortable with the stability of the situation for this particular opportunity, so we are going to officially wave you off for 24 hours," Mission Control radioed Discovery commander Eileen Collins.
Florida's Kennedy Space Center will remain the first choice, although similar weather is expected for Tuesday. Flight director LeRoy Cain said if the weather is unacceptable, then he will direct Discovery to Edwards Air Force Base in California and, barring that, to the White Sands Missile Range in New Mexico.
As for Monday, Cain said, "It was a close day; it wasn't quite good enough."
"There's no agony," NASA Administrator Michael Griffin said from the landing strip. "We're going to land (Tuesday) one way or another, one place or another, and all we're talking about is where."
Before the weather deteriorated, Discovery had been set to land at Florida's Kennedy Space Center before dawn.
Observed astronaut John Herrington, who was at the runway waiting: "It's better to be on the safe side." In fact, thick clouds hovered over much of the landing site at the designated touchdown time.
Shuttles have landed 61 times at Kennedy, 49 times at Edwards and only once -- way back in 1982 -- at White Sands, NASA's last-ditch resort for a shuttle touchdown. Columbia ended up landing in a sandstorm in New Mexico on that third shuttle flight and, for decades, workers were still finding sand in the shuttle's nooks and crannies.
Kennedy became the main landing site in 1991, taking over from Edwards, because of the several days and estimated $1 million saved in ferrying the shuttle cross-country atop a modified jumbo jet.
Discovery has enough fuel and supplies to stay in orbit until Wednesday, but NASA wants to hold out that option only if a technical problem arises that needs time to be resolved.
The astronauts planned to spend their extra 14th day in orbit relaxing and gazing out the windows at the magnificent earthly views.
Discovery's flight to the international space station may be the last one for a long while. NASA grounded the shuttle fleet after a slab of insulating foam broke off Discovery's external fuel tank during liftoff -- the very thing that doomed Columbia and was supposed to have been corrected.
After Discovery's July 26 launch, the shuttle spent nine days hitched to the space station, where astronauts resupplied the orbiting lab and removed broken equipment and trash -- one of the main goals of the mission. Discovery was the first shuttle to visit the station since 2002.
As a result of Columbia, Discovery's crew inspected their ship for damage on five different days during the mission and also did a spacewalk to test new repair techniques. A failed space station gyroscope was replaced during a second spacewalk. And in a third, unprecedented spacewalk, two protruding thermal tile fillers were removed that could have caused dangerous overheating during re-entry.
Columbia was doomed by a 1.67-pound piece of foam that broke free from an external fuel tank at launch. The foam pierced a hole in the ship's left wing and as the spacecraft re-entered the Earth's atmosphere, searing gases melted the wing from the inside, causing the ship to break apart. All seven astronauts aboard were killed.
NASA officials' excitement over Discovery's return to space was dampened by video that showed a nearly 1-pound chunk of foam breaking free from Discovery's external tank shortly after liftoff. The foam did not strike Discovery.
The agency quickly grounded future flights, saying that more work must be done, despite spending hundreds of millions of dollars to redesign the tank.