I was don’t remember the first shuttle launch, but I remember the principal coming over the loudspeaker in 3rd grade to announce that the Challenger had been lost. We observed a moment of silence. It was a sober note in the booming, self-confident America of the 1980s, of which NASA’s space shuttle program was part and parcel. I remember being mesmerized by Kennedy Space Center as a kid, coming home with a t-shirt showing a shuttle framed by pink puffy paint. All of this contributed to where I am now — at NASA’s Jet Propulsion Laboratory, writing about robotic explorers to the outer solar system. So at the final shuttle launch, I joined hundreds of others at JPL, one of the key places where our space program began to take shape, to commemorate the end of an era. The whole room clapped and cheered as the engines burned and the shuttle lifted off cleanly. I won’t mourn the shuttle per se so long as America keeps yearning to explore. But I do worry that the harsh economic reality will keep us from pushing boundaries, testing our limits, asking questions about the places we’ve never been. To me, these are the things that make us human.