Earlier this morning, the connecting hatches between shuttle Atlantis and the International Space Station closed for the last time.

I know I keep writing variations on the same theme, “last this” and “final that,” and it’s probably starting to get a bit tedious for Readers who don’t share my fascination with human spaceflight. But please understand that I have to do this. Each and every one of these landmarks is important. We need to mark them, because these last two weeks are the closing words of a chapter in a future history book. And very possibly, they’re the end of several generations’ dreams as well. I’m trying to be optimistic about the future of the space program, I really am. I know of four separate private-industry groups that are working on manned vehicles capable of reaching low-earth orbit, including one spaceplane that’s designed to land on a runway like the shuttle, and there are probably more I don’t know about. But with news that Congress is looking to cut NASA‘s annual budget — which, by the way, is not the outrageously high percentage of the federal budget most people believe it is, but is in fact smaller than the amount we’re spending every year to air-condition military tent cities in Afghanistan — as well as rumblings that some folks want to deorbit the just-barely-finished station as soon as 2015… with a cultural zeitgeist that no longer seems to have much interest in the Final Frontier, and a nagging, dread-filled sense that the whole damn country is falling apart while we surf for porn on the InterWebs… well, it’s hard to keep telling myself the United States is going to be launching people into space again anytime soon, let alone going back to deep space. American robots, maybe… but actual Americans? I just don’t know anymore. Once upon a time, I thought it was simply, logically inevitable that human beings — Americans, to be precise — would explore and settle and spread out across space. It seemed as natural a progression to me as manifest destiny must’ve seemed to people in the 19th century. And of course, I figured the progression would never falter, but just keep going ever higher, ever farther. But now I’m wondering, with a big tablespoon of bitter disappointment, if perhaps these ideas were only the naive thinking of a kid who watched too much Star Trek and was dumb enough to believe.

Before the crew of Atlantis returned to their ship for good this morning, they assembled with the crew of the ISS for a little ceremony, in which the station commander was formally presented with a model of a shuttle orbiter and a small American flag. The model will stand in for a more impressive monument, commemorating the winged spacecraft that assembled the outpost in space. It was immediately mounted on a bulkhead alongside the forward hatch in the station module known as Node 2, where 35 shuttle missions have docked. The flag, meanwhile, is something of a sacred NASA artifact. It flew with astronauts John Young and Robert Crippen on board shuttle Columbia during the very first mission, STS-1, 30 years ago. It will now live on the ISS, fastened to the Node 2 hatch cover itself, with the idea that it will remain there until the next American crew on board an American spacecraft comes up to retrieve it. And then if all goes well, it will fly again the next time a manned American spacecraft ventures beyond low Earth orbit, bound for the moon, or Mars, or the asteroids.

I only hope that it’s not still there, forgotten, when the ISS comes back down to Earth…

Atlantis is scheduled to undock shortly after midnight tonight, Mountain time.