On the ride home Wednesday, the space shuttle will make the first coast-to-coast re-entry since Columbia shattered in the sky over Texas in 2003 and sent tens of thousands of pounds (kilograms) of wreckage raining down on at least two states.
Discovery was not supposed to re-enter over the entire United States - just Florida after zooming up from the southwest over Central America and the Caribbean . But that original plan would have entailed a pre-dawn landing, and shuttle commander Pamela Melroy preferred a safer, easier touchdown in daylight, said shuttle program manager Wayne Hale.
This 15-day mission is longer than most - and more stressful, too, with the astronauts' impromptu repair to the torn solar wing at the space station. As a result, crew fatigue must be considered, Hale said Monday.
Discovery's new path will have it descending early Wednesday afternoon over the Canadian coast and the Pacific Northwest, down across the Midwest and the South, and on into Florida.
"For an undamaged orbiter - and we'll confirm that it's undamaged - this constitutes a very minimal and deemed to be a safe risk to fly over the middle of the United States," Hale said.
Sensors embedded in the wings indicated eight potential impacts, but that doesn't necessarily mean they were hit. Those readings simply may reflect the normal expanding and contracting of the wing's reinforced carbon material in space, Hale said.
Engineers will review this late data into Tuesday, and only then will mission managers give Discovery the green light to come home.
Melroy called down a Cape Canaveral weather report Monday.
"We could see the runway from orbit, so we're thinking the weather there is looking pretty good," she radioed. Mission Control replied that forecasters were keeping an eye on the wind but it should be within limits.
Earlier in the day, Discovery flew a victory lap around the space station after undocking, primarily for picture-taking. Because of a computer problem, pilot George Zamka had to manage without key navigation information.
The space station's newest resident, Daniel Tani, wished his shuttle colleagues a safe trip home.
"I miss you already," he called out.
Shuttle Atlantis, meanwhile, is being prepped for launch as early as Dec. 6 to the space station. Hale said the shuttle could be ready to carry up a European laboratory sooner, but must wait for the space station crew to finish the construction job that the Discovery astronauts began involving the new pressurized compartment, Harmony.