This was the scene in Florida early this morning as space shuttle Discovery lifted off before dawn for a rendezvous with the International Space Station:

Watch that video a couple of times, kids, and savor it with a bit of melancholy nostalgia, because this will be the last time anyone ever sees the golden flare of a space shuttle’s main engines and solid-rocket boosters combined to banish the darkness. This flight is the last scheduled nighttime launch, and the last that will feature a full crew complement of seven astronauts. After this, only three missions remain before the surviving shuttles are sent off to the museums… and the way things are going, manned American spaceflight may be going with them.

I’ve been wanting to write for some time about the impending end of the shuttle program, as well as the president’s desire to spike the Constellation program that would replace it, but it’s such an emotional issue for me, and I am so ambivalent about the details, that the subject tends to elude me. Still, here are a few quasi-coherent thoughts:

On the one hand, the shuttles are 30 years old, give or take, a long operational life for any complex machine but especially one that’s routinely subjected to the extraordinary stresses a spacecraft must endure. I imagine there are all kinds of metal-fatigue issues in the fleet’s airframes (spaceframes?) after so long. Add to that the little matter that the shuttles have never managed to achieve the level of economy or quick turnaround they were supposed to have — in other words, it’s more expensive to operate them and more work to refurbish them between flights than the designers hoped — and the case for retiring them is pretty obvious.

(Notice I did not mention safety concerns as a reason to retire them. As I’ve noted before, I think Americans in general and the high muck-mucks at NASA especially have become needlessly timid about these spacecraft, which actually have pretty impressive safety records, all things considered. That’s not to say I think we should take unnecessary risks — such as launching Challenger in spite of repeated warnings about the cold weather from the engineers who actually built the damn thing — but we should acknowledge that there are risks and always will be, and just make up our minds that a certain level of risk has got to be acceptable if we’re going to accomplish certain things.)

Practicality aside, though, I do hate to think about retiring them. My love affair with the space shuttle goes back to my childhood, when I dreamed of being an astronaut myself and riding one of those fabulous machines to work everyday. I still have a “non-fiction” paperback my parents gave me for Christmas one year, which painted an insanely optimistic vision of what our space-shuttle future — what should have been our present — was going to be, a world surrounded by orbital manufacturing plants, research labs, and hotels, all serviced by a fleet of dozens of shuttles, refined through the decades into such efficient and reliable machines that traveling aboard them is about as remarkable as catching a commuter plane to Vegas for the weekend. I came to understand, years and years later, that the shuttle could never have been what this book promised — they are a mass of design compromises that try to meet multiple, sometimes conflicting purposes, and they don’t excel at any of them — but I nevertheless continue to think they’re beautiful machines, and just plain neat, and I don’t want to see them go away.

Of course, my biggest concern with retiring them right now is that there’s nothing to replace them. Which brings me to the Constellation program, the effort to develop a more efficient (read: cheaper) and safer spacecraft to ferry astronauts to the ISS and eventually back to the Moon. I’ve been dubious of the Constellation from the start, concerned that the central idea of sticking an Apollo-style capsule on top of a shuttle’s solid-rocket booster wouldn’t work. I know something about those boosters, you see, and the way solid propellant burns in contrast to liquid-fueled rockets; it seemed to me that the poor buggers sitting up there on top of the stack would be in for a tremendously rough ride, especially as the fuel burns down (or up, to be more precise) and you start developing voids and air bubbles inside the tube, leading to random spurts and drop-offs in power. Sure enough, an analysis back in ’08 revealed that the Constellation vehicle — comprising an Orion capsule and an Ares I booster — would experience “severe vibrations” during the initial moments of the boost phase. (The shuttle SRBs produce vibrations, too, but the different configuration of a shuttle stack renders them relatively harmless.) I’m no engineer, obviously, but Constellation has always struck me an el-cheapo, quick-fix option, potentially more dangerous than our current spacecraft, the risks of which are at least known. So I’m not especially troubled by the president’s suggestion of axing a program I don’t believe in… but without it, there’s nothing else. Which leaves American astronauts hitching rides on Russian spacecraft for the foreseeable future. And that troubles me. Because it feels too much like the beginning of an ignominious end.

I foresee a day, not very far off, when Americans don’t travel into space at all anymore… when we occasionally send up a robot to look around but the glory days of the Apollo missions are nothing more than a footnote, and the thought of putting a real human being out there is met with complete apathy. Or fear. Or moralizing about what a waste of money and time the whole thing was. And meantime, the space shuttles, the ships of my youthful dreams, will be gathering dust at the Smithsonian, quaint curiosities of a time that we somehow allowed to slip through our fingers.

Told you: not terribly coherent. But certainly filled with melancholy nostalgia.