CAPE CANAVERAL, Fla. -- On the eve of NASA's end to the shuttle program, the four astronauts making the final journey completed one last task.
They released the last satellite to be launched from a space shuttle: an eight-pound box covered with experimental solar cells.
Over the three decades of the shuttle era, 180 satellites and other spacecraft have been deployed by the entire fleet -- from tiny ones like Wednesday's PicoSat to megaton whoppers like the Hubble Space Telescope.
Shuttle commander Christopher Ferguson and his crewmates checked their critical flight systems for today's planned 5:56 a.m. landing at Florida's Kennedy Space Center, not quite an hour before sunrise. Everything worked perfectly. Excellent weather was forecast to wind up the 135th flight of the program.
The astronauts and the flight controllers who will guide them home said Wednesday they were starting to feel a rush of emotions.
"It's going to be tough," Ferguson said in a series of TV interviews. "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."
Flight director Tony Ceccacci, who was slated to preside over Atlantis' return to Earth, refrained from publicly sharing his sentiments -- until Wednesday.
"You guys must know that we do have a motto in the Mission Control Center that flight controllers don't cry," Ceccacci told reporters. "So we're going to make sure we keep that."
Atlantis departed the International Space Station on Tuesday, after restocking it with a year's worth of supplies. Among the shuttle highlights noted Wednesday was the construction of the station, a nearly 1 million-pound science outpost that took 121/2 years and 37 shuttle flights to build.
Space station astronaut Michael Fossum posted on Twitter a photo of the shuttle docked to the station 250 miles 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?"
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.
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 moon as the prize.
Throughout their 13-day mission and again Wednesday, the 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 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."
Once Atlantis is safely back on Earth, Ceccacci planned to read a speech to his Houston flight control team and gather them around to watch the crew walk around the last shuttle one last time -- 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.