Theand were awaiting word from Mission Control to fire their braking rockets and head for home at the expected time of 4:47 a.m. when controllers announced early Monday that low clouds over Cape Canaveral would postpone the landing.
"We've been working this pretty hard as I'm sure you can imagine from our silence down here," Mission Control radioed Discovery commander Eileen Collins. "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."
When cloud cover still threatened after the second of two landing opportunities, NASA officials rescheduled the landing for Tuesday. For the next attempt, they will consider alternate landing sites at Edwards Air Force Base in California and at the White Sands Missile Range in New Mexico, in addition to Florida's Kennedy Space Center.
"There's no agony," NASA Administrator Michael Griffin said from the landing strip.
Griffin said that on Tuesday, "We're going to land one way or another, one place or another, and all we're talking about is where."
Weather delays of space shuttle landings are fairly routine, CBS News Correspondent Lee Cowan reports. But because the Discovery mission is under a public microscope, even such a standard procedure is getting extra attention.
"There's a lot of things to think about," said Flight Director LeRoy Cain, who was also director for Columbia's fatal flight on Feb. 1, 2003. "There's a lot of things to worry about, and that's what I get paid to do is to worry - and I do it a lot."
There are four possible landing slots Tuesday: two in Florida at the Kennedy Space Center, and two in California at Edwards Air Force Base. The next chance to land is 5:07 a.m.
Early Show co-anchor René Syler asked former astronaut Kathryn Thornton to describe what the crew might have felt upon being told by Mission Command to stay in space at least another 24 hours.
"You know, there's no bad day in space, but I think they were probably disappointed," Thornton said. "They've already had one extension on this mission. They were suited up, strapped in and ready to come home and see their families. I would think it would be a bit of a disappointment."
Before the weather deteriorated, Discovery had been set to land at Florida's Kennedy Space Center before dawn. Its return to Earth would have concluded the first shuttle flight since Columbia disintegrated while re-entering the Earth's atmosphere 2 1/2 years ago.
Observed astronaut John Herrington, who was at the runway waiting: "It's better to be on the safe side."
And from day one, NASA played it safe with Discovery, Cowan reports. The shuttle's first launch attempt was scrubbed, and it did not take off until a week and a half later.
And playing it safe was a logical choice Monday morning, CBS News Space Consultant Bill Harwood told Syler.
"The weather was very dynamic this morning … hard to predict," Harwood said, explaining that a test vehicle flying above Florida became disoriented due to the cloud cover.
The order to delay landing came from chief astronaut Kent Rominger, who was flying the shuttle training aircraft through the cloudy sky over Kennedy.