The space shuttle Atlantis crew before their July 21 launch: Their 12-day mission to the International Space Station was the 30-year shuttle program's final flight.

REUTERS/Scott Audette

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he video: Atlantis is home. The space shuttle cruised into Kennedy Space Center for a "flawless" landing at 5:57 a.m. Thursday morning, marking the conclusion of the 135th — and last — flight of NASA's 30-year shuttle program. The organization is facing an uncertain future, with no immediate means to send American astronauts into space.

The reaction: "It was a sentimental occasion," says CNN. NASA's 30 years of low-orbit exploration should be celebrated for its many successes. But the knowledge that the U.S. won't be headed back into space "is not A-OK," says Storer H. Rowley at the Chicago Tribune. As Americans, we need "to explore, to push the limits, to risk life and limb." Yes, says Meg Urry at CNN. But the shuttle is an "aging workhorse that should be put to pasture." NASA needs to look past human spaceflight to the possibilities of robotic space exploration — of asteroids, Mars, and beyond. "Saying goodbye to the shuttle isn't saying so long to space." It's hello to the future. Watch Atlantis' swan song: