The astronauts and support team for NASA's final space shuttle flight say they're feeling a rush of emotions as they head toward Thursday's historic landing.
"You know what? I really do feel like it's coming near the end," Atlantis commander Chris Ferguson told an interviewer Wednesday.
"It's going to be tough," Ferguson said during a series of TV interviews 24 hours before the scheduled touchdown. "It's going to be an emotional moment for a lot of people who have dedicated their lives to the shuttle program for 30 years. But we're going to try to keep it upbeat. We're going to try to keep it light, and we're going to try to make it a celebration of the tremendous crowning achievements that have occurred over the last 30 years."
Among the highlights noted Wednesday by the four-member crew as well as flight controllers: the 180 satellites and other spacecraft deployed into orbit by the space shuttle fleet; and the construction of the International Space Station, a nearly 1 million-pound science outpost that took 12½ years and 37 shuttle flights to build.
Atlantis departed the space station Tuesday, after restocking it with a year's worth of supplies.
One last satellite
The very last satellite to be released from a space shuttle popped out of a can Wednesday: a little 8-pound (3.7-kilogram) box covered with experimental solar cells. PicoSat will conduct experiments for the Defense Department, testing whether a nanosatellite can be used as a reference point for ground tracking stations and monitoring space weather.
Entry flight director Tony Ceccacci told journalists that the satellite also took pictures of Atlantis in orbit and would send them down to the ground.
As soon as the mini-satellite was on its way, astronaut Rex Walheim read a poem that he wrote to mark the occasion. It was the first of many tributes planned over the next few days; on Wednesday evening, the Empire State Building in New York was due to light up in red, white and blue in honor of the space shuttle program.
Walheim read: "One more satellite takes its place in the sky, / the last of many that the shuttle let fly. / Magellan, Galileo, Hubble and more / have sailed beyond her payload bay doors. / They've filled science books and still more to come. / The shuttle's legacy will live on when her flying is done."
Flight controllers applauded back in Houston.
Thank-yous galore
On this last full day of this last mission, Ferguson told the controllers, "I'd love to have each and every one of you to stand up and take a bow, a round of applause. Then there would be no one to applaud and there would be nobody to watching the vehicle ... but believe me, our hearts go out to you."
Crew members also radioed down thanks to support teams at NASA's White Sands base in New Mexico, at Goddard Space Flight Center in Maryland and elsewhere. Ferguson said thanking all the teams backing the shuttle program individually would be an impossible task. "We'd be here for another 135 missions trying to do that," he told Mission Control.
Atlantis' crew received words of encouragement in return. After the astronauts' wake-up call, featuring music from Aaron Copland's "Fanfare for the Common Man," Mission Control played a recorded salute from workers from Kennedy Space Center. "See you back at wheels stop," the crowd chanted.
The final day was emotional at Johnson Space Center in Texas.
"You guys must know that we do have a motto in the Mission Control Center that 'flight controllers don't cry,'" Ceccacci told reporters, as his eyes misted up just a bit. "So we're going to make sure we keep that."
Practicing for landing
Ferguson and his crew checked their critical flight systems and practiced for Thursday's planned 5:56:58 a.m. ET landing at Kennedy Space Center, not quite an hour before sunrise. Everything worked perfectly. To top it off, excellent weather was forecast to wind up the 135th flight of the space shuttle era.
There's a second landing opportunity available at 7:33 a.m. ET. And if Atlantis can't land in Florida on Thursday for some reason, backup landing strips could be opened up in California and New Mexico on Friday.
Asked by a TV interviewer what he would tell all those watching Atlantis' return to Earth, Ferguson echoed what he told the lead team of flight controllers on Tuesday.
"Take a good look at it (Atlantis) and make a memory because you're never going to see anything like this again," he said. "It's been an incredible ride."
Space station astronaut Michael Fossum posted on Twitter a photo of the shuttle docked to the station 250 miles (400 kilometers) above the blue planet, which he snapped during last week's spacewalk. He noted in the tweet: "When will such beautiful ship dock again to ISS?"
Next step in spaceflight
NASA already is shifting gears. It's working with private companies eager to take over cargo runs and astronaut flights to the space station. The first supply trip is expected to take place by the end of this year. Astronaut trips will take more time to put together, at least three to five years. In the meantime, NASA will depend on the Russians to ferry its astronauts back and forth, at a cost of up to $63 million per seat.
The long-term destination is true outer space: sending astronauts to an asteroid by 2025 and to Mars the following decade. That's the plan put forth by President Barack Obama. His predecessor wanted the moon as the prize, but Obama pulled back from that goal after an independent panel said it was unachievable at current budget levels. Even now, budget worries are casting a shadow over the revised plans for the space program.
Throughout their 13-day mission and again on Wednesday, Atlantis' astronauts stressed the need for a decades-long space exploration plan that does not change with each incoming president.
Ceccacci, whose Mission Control experience dates back to the first shuttle flight in 1981, said it's tough to think about all the experience that will be walking out the door following this mission. Thousands of layoffs are looming at the various NASA centers; about 2,000 shuttle workers at Kennedy alone will get pink slips starting Friday. That's on top of the massive cutbacks already made.
"We know there's going to be a rough spot for a while," Ceccacci said. "But we hope that when we do get a good plan, a good direction, a good mission, that we can come back in here and do what we've been doing for the past 30 years for the shuttle and the years before that with Mercury, Gemini and Apollo."
Ceccacci plans to read a speech to his Houston flight control team, once Atlantis and its crew are safely back on Earth, but there will be none of the flag-waving, cigar-smoking celebrations seen during the moon-landing days. Smoking is no longer permitted in the control center, he reminded journalists.
Rather, Ceccacci said he will gather flight controllers around to watch Ferguson, co-pilot Doug Hurley, Walheim and Sandy Magnus walk around the last shuttle one last time on the runway — so the controllers can "soak it in ... and congratulate each other on a job well done."
Atlantis is the last of the shuttles to be retired. It will remain at Kennedy Space Center, eventually going on public display at the visitors complex. Discovery is bound for the Smithsonian Institution in suburban Washington, and Endeavour for the California Science Center in Los Angeles.
This report includes information from The Associated Press' Marcia Dunn and msnbc.com's Alan Boyle.
