And shuttle co-pilot Jim Kelly admits there was a "moment of trepidation" as commander Eileen Collins was about to execute the de-orbit burn this morning. It was at that point that Columbia started to break apart 2 1/2 years ago.
Kelly says he kept watching for warning signs of possible trouble -- though he admits there might not have been much that could have been done about it.
But Kelly says the astronauts have to put their trust in the people who sent them into orbit. And he says because of the changes made following Columbia, this crew had a much better idea of what kind of shape the shuttle was in.
Collins, meanwhile, says the biggest accomplishment of this flight was simply "getting the shuttle flying again."
Discovery's crew, braving the hellish fire of re-entry for the first time since Columbia's ill-fated descent, flew safely back to Earth Tuesday, gliding to a predawn California touchdown to close out an action-packed mission.
With Collins at the controls, Discovery swooped to a ghostly, tire-smoking touchdown on runway 22 at Edwards Air Force Base in California's Mojave Desert at 8:11:22 a.m. EDT, one day late because of concern about cloudy weather in Florida. The crew had two shots at a Kennedy Space Center landing Tuesday, but off-shore storms forced entry flight director LeRoy Cain to divert the shuttle to California.
"It looks fantastic," Collins said of the shuttle's condition, after the crew walked around it for the traditional post-landing inspection.
It was the 50th shuttle landing at the famed Air Force test center and only the sixth carried out in darkness. But Collins, a 1990 graduate of Air Force Test Pilot School at Edwards, had no problems, reports CBS News Space Consultant Bill Harwood, guiding Discovery to a picture-perfect touchdown.
Barreling down the runway at more than 200 mph, pilot James "Vegas" Kelly deployed a large braking parachute, the shuttle's nose dropped and the craft slowly rolled to a halt.
"Houston, Discovery, wheels stopped," Collins radioed.
"Roger, wheels stopped, Discovery," called astronaut Ken Ham from mission control. "And congratulations on a truly spectacular test flight. Stevie Ray, Souichi, Andy, Vegas, Charley, Wendy and Eileen, welcome home, friends."
"Thank you, those are great words to hear," Collins replied. "We're happy to be back and we congratulate the whole team on a job well done."
President Bush offered his congratulations to the Discovery team during a press briefing at his Texas ranch.
"It was a great achievement," the president said. "It was an important step for NASA as it regains the confidence of the American people and begins to transition to the new mission we've set out for NASA."
Discovery's high-speed touchdown was the final chapter in the 114th shuttle mission, a voyage spanning 5.8 million miles and 219 complete orbits since blastoff July 26 from pad 39B at the Kennedy Space Center.
Collins, Kelly and their crewmates — flight engineer Stephen "Stevie Ray" Robinson, Andrew Thomas, Wendy Lawrence, Charles Camarda and Japanese astronaut Soichi Noguchi — were expected to climb out of the shuttle for quick medical checks before a traditional walk-around inspection on the runway.
"I think the crew performed beyond fantastically well. The flight directors, who haven't controlled the shuttle for 2½ years, performed fantastically well," said NASA administrator Michael Griffin. He told reporters about an hour after the touchdown that the space agency hopes to get another shuttle into space this year, but wouldn't promise it.
"We always knew it was going to be a test flight and it was going to give us a lot of information, and we've come back with a lot learned," said shuttle program manager Bill Parsons. "I think I'll agree with the administrator, this was a wildly successful mission in so many ways."
With Discovery back safely on the ground, NASA's full attention now shifts to figuring out what caused multiple pieces of foam insulation to fly off Discovery's external tank during launch. Columbia was brought down by wing damage caused by a foam debris strike during launch and the No. 1 priority of NASA's return to flight was fixing the insulation to minimize foam shedding.
But during Discovery's launch, a 0.9-pound chunk of foam peeled away from the tank just after solid booster separation. Two other relatively large pieces separated from the tank near the point where the shuttle's nose attaches to bipod struts and a fourth piece broke away from another area.
But the foam is not the only problem for the next launch.
The shuttle Atlantis had been scheduled for launch on the second post-Columbia mission in September, but resolution of the foam problem made that target window problematic. Now, with Discovery back on the ground in California, a September launch is no longer thought to be possible. Discovery must be ready for launch as a rescue vehicle in case Atlantis suffers any significant damage on its flight and Tuesday's West Coast landing will add a week or so to Discovery's turn-around time.
It will also cost NASA an extra $1 million, reports CBS News Correspondent Peter King, and force the astronauts' families waiting at the Kennedy Space Center to wait a little longer for their reunions.
Rav Camarda, the mother of astronaut Charles Camarda, told WCBS-TV, she was feeling "a little bit of everything."
And, at her home in New York City's Ozone Park, she had a message for her son: "Thank God you are home. God bless you. And don't let me go through this again. I'm too old to go through this again."
Atlantis' launch already had slipped to no earlier than Sept. 22, giving it just four days to get off the ground before the September launch window closes. It now appears Discovery will be unable to support that window, even if the foam problem can be resolved in time.
The only other available launch window before the end of the year is a three-day period in November. Another short window opens in January but the first lengthy opportunity to send a shuttle back to the international space station is in March.
Despite the disappointment over the launch-day foam events, Discovery's crew chalked up a near flawless mission, delivering tons of supplies to the space station and staging three spacewalks to install a new stabilizing gyroscope, an external tool and spare parts depot and to demonstrate potential heat-shield tile and wing leading edge repair techniques.
The astronauts also carried out an unprecedented inspection of the shuttle's heat shield, using a large sensor-equipped boom to examine the wing leading edges and nose cap and utilizing cameras on the station to photograph the orbiter's underside in great detail.
During Columbia's decent on Feb. 1, 2003, instruments on the shuttle recorded the first signs of abnormal heating just four minutes and 50 seconds after entry interface as plasma began.
But Tuesday, Discovery's fall to Earth appeared problem free as the shuttle streaked toward California.
CBS News Space Consultant William Harwood has covered America's space program full time for nearly 20 years, focusing on space shuttle operations, planetary exploration and astronomy. Based at the Kennedy Space Center in Florida, Harwood provides up-to-the-minute space reports for CBS News and regularly contributes to Spaceflight Now and The Washington Post.