The Space Shuttle Discovery hitched a ride today on NASA's 747 to National Air and Space Museum in Washington, D.C. It's yet another period at the end of the melancholy final paragraph of the Space Shuttle program. So long, Discovery. And thank you for the memories.

Through its history, Discovery has been a symbol of the enduring persistence of the shuttle mission. It was the first shuttle to return to flight after the tragic Challenger explosion, and again after Columbia disintegrated in 2003. It was the first shuttle to dock with the International Space Station, and it helped launch the Hubble Space Telescope. It's earned its air-parade around Cape Canaveral and the nation's capital today. And its permanent place in history.

The Discovery is the first of the three remaining shuttles to ship off to its final resting place. Over the next year, the remaining two—Endeavour and Atlantis—will be decommissioned, and sent to the California Science Center and the Kennedy Space Center Visitor Center, respectively. It's a sad—but ultimately necessary—end to a Shuttle program that has outlived its practicality and, more importantly, its funding.

Goodbye, Discovery: Legendary Space Shuttle Takes Its Final Flight

We're not done with space travel entirely, of course. SpaceX, one of the private companies picking up the galactic mantle, has been approved to travel to the International Space Station on April 30th. It will be the first time that any private vessel has made that trip. But the private space tourism vessels won't be pushing boundaries any further than have already been pushed. That's still the province of NASA.

The shuttle was costly, and safety issues were myriad by the end of its run. But more importantly, the program had reached its limits. Its function was no longer core to its original spirit of exploration. Let the billionaires fight over low orbit holidays, and ISS taxis. NASA's business is out at the farthest reaches of mankind's reach. And shuttles like Discovery aren't going to get them there.

After the Constellation debacle, we're decades away from NASA's next manned spacecraft launch. There's no saying what for it will take, other than that the mission will take us further than we've ever been, and will teach us more than we've ever known about space. Just like Discovery did for decades. Just like NASA's always done. [NASA]

Image credit: Laura Bly via Twitter