I am a child of the Space Shuttle era. I remember big exploded view posters of the spaceship in classrooms. I remember building models of it out of plastic and assembling gliders in its shape out of foam. I remember sitting silent with my classmates watching the television news after Challenger exploded on January 28, 1986. Six years later, I remember working as an instructor at the New Mexico Museum of Space History's summer "Shuttle Camp," a name that will soon seem retrograde if it doesn't already.

The end of the shuttle program has inspired a flood of bittersweet nostalgia. The end of an era, many say. But what era? What period's conclusion are we lamenting?

During the 1950s and 1960s, space exploration was primarily a proxy for geopolitical combat. It was largely symbolic, even if set against a background of earnest frontiersmanship. First satellite, first man in space, first spacewalk, first manned moon mission, and so forth. Space as a frontier was a thing for science fiction fantasy, although we dipped our toes far enough across that border to make it clear that such exploration was possible, even if not yet feasible.

By the 1970s, space had become a laboratory rather than a frontier. Despite its status as "space station," Skylab was first called Orbital Workshop, making it sound more like dad's vision for his garage than like Kubrik's vision of 2001. The fact that Skylab was permanently disfigured during launch only concretized the program's ennui. Space exploration became self-referential: missions were sent to SkyLab in order to repair SkyLab.

The Space Shuttle turned the workaday space lab into a suburban delivery and odd-jobs service. Satellites were deployed, space labs serviced, probes released, crystals grown. Meanwhile, the aspects of space travel that really interest people—such as the fact that it's travel in motherfucking outer space—were downplayed or eliminated.

For one of our Shuttle Camp classroom gimmicks, we'd have a kid hold a real high-temperature reusable surface insulation tile, one of the 20,000 such tiles that line the orbiter's underbelly to facilitate reentry. After finishing her freeze-dried space spaghetti and Tang, this unassuming third-grader would clasp at the edges of the impossibly light tile, which seemed like little more than styrofoam. We'd heat its surface with a propane torch until it glowed red with heat and danger, only to dissipate a few moments later. The danger was real, and the kids knew it. A decade later, a chunk of foam insulation would break free of Columbia's external fuel tank on launch and damage part of this thermal protection system, dooming the orbiter to destruction.

Rhetorically speaking, the very idea of a reusable space vehicle is contrary to everything that space travel had previously represented—wealth and power for one, but also enormity and smallness and risk and brazenness and uncertainty and dark, dark darkness—expedition rather than experimentation. It's no wonder the space spaghetti and the thermal protection tiles were so interesting to those kids. They represented the experience of space (the frontier) rather than its taming as laboratory (the settlement). Look at the Saturn V. It's a badass rocket. Now look at the Space Shuttle. It's a humble tractor.

We went to the moon not because it was easy but because it was hard. We went to low Earth orbit because, you know, somebody got a grant to study polymers in zero-gravity, or because a high-price pharmaceutical could be more readily synthesized, or because a communications satellite had to be deployed, or because a space telescope had to be repaired. The Space Shuttle program strove to make space exploration repeatable and predictable, and it succeeded. It turned space into an office park.

The official mission of the final Space Shuttle, STS-135, reads more like a joke from The Office than a science fictional fantasy: "Space shuttle Atlantis is carrying the Raffaello multipurpose logistics module to deliver supplies, logistics and spare parts to the International Space Station." Among its tasks: the delivery of a new tank for a urine recycling system, and the removal of a malfunctioning space sewage pump.

In first grade, during the early days of the Shuttle program, I remember writing and illustrating "astronaut" as a response to the dreaded "what do you want to be when you grow up" prompt. I didn't really want to be an astronaut, but my first illustration, garbage collector, had been rejected as unambitious. If only I'd known that the two would turn out to be essentially identical.