Everything the astronauts of space shuttle Atlantis do, they do for the last time in the program's history.
They spent today slowly inspecting the heat shield tiles on the belly and wings of their orbiter. On Sunday, they are scheduled to dock with the International Space Station.
The astronauts were settling in and getting their space legs after Friday's launch -- a spectacular sight to the estimated one million people who crowded around the space center to see it happen.
The shuttle rose on a streak of flame that was almost blinding to see, going higher and higher and higher. Within a minute it punched a hole in the clouds above it and disappeared from sight, leaving a pillar of steam that slowly dissipated in Florida's muggy air.
"We got to witness something really, really special and something amazing," said William H. Gerstenmaier, head of NASA's space operations.
But it may be the last time America launches its own astronauts for many years. At the Kennedy Space Center, throngs of people applauded, cheered -- and in some cases wept. This part of Florida has lived in large part for space shuttle launches, and there is not a clear plan for what comes next.
Atlantis' mission sounds fairly mundane: it is carrying a year's worth of preserved food, clothing spare parts and other supplies for the station's six crew members. It is scheduled to land on July 20 at 7:06 a.m., ET, though NASA will give the astronauts an extra day if they can conserve enough fuel and power.
And then it will become a museum piece; a new building is planned for it at the visitors' center here.
For several years, American astronauts will probably have to rely on the Russian space program, with its Soyuz capsules, to get to the space station. NASA is also keeping an eye on the Chinese, who have a small and slow -- but methodically planned -- program of their own.
They talk of building a small space station and eventually going to the moon.
Some people at NASA quietly say they hope the Chinese succeed -- and give the U.S. a healthy kick in the pants. There would be nothing like a rekindling of the 1960s space race, they say, to get Americans interested in a more aggressive space program.
But that is not said publicly. If anything, America talks of collaborating with other countries if explorers are ever to reach out beyond Earth orbit.
NASA Administrator Charles Bolden released a bittersweet statement moments after Atlantis reached orbit:
"With today's final launch of the space shuttle we turn the page on a remarkable period in America's history in space, while beginning the next chapter in our nation's extraordinary story of exploration," Bolden said. "Tomorrow's destinations will inspire new generations of explorers, and the shuttle pioneers have made the next chapter of human spaceflight possible."
But the harsh reality is that years will probably pass before America sets off for those future destinations. The Obama administration has proposed that NASA build a new, more powerful booster to take astronauts into deep space, perhaps to a passing asteroid and ultimately on the Mars.
But the booster is several years from completion, and in the meantime, NASA says the number of space workers here in Florida, which peaked at 15,000 people, will shrink to 8,200. Private companies have been invited to take over the job of ferrying astronauts to the space station, but none has yet put astronauts in orbit.
Bob Cabana, a former astronaut who now heads the Kennedy Space Center, tried to be encouraging today.
"Change is difficult," he said, "but you can't do something else, you can't do something better, without it."