TITUSVILLE, Fla. — The space shuttle Atlantis now hangs in a vast hall, a prime attraction for the Kennedy Space Center here on Florida’s eastern coast. Its 33rd and final mission ended just over six years ago, capping 30 years and 135 flights for NASA’s Space Shuttle Program.

Looking at the Atlantis, it was hard to decide if it appears paused in mid-flight — or trapped in a thin, transparent amber.

Six years is long enough that neither of my children can remember watching a manned flight launched by NASA. For those of us who grew up watching space-shuttle launches on TV, that seems strange. All the more so, I suspect, for Americans reared with astronauts such as Alan Shepard and Buzz Aldrin as their heroes and celebrities.

The private sector is assuming the old mission of spacecraft like the Atlantis: shuttling passengers and cargo into low-Earth orbit. NASA itself plans more manned missions in the future, going back to the moon in preparation for an eventual mission to Mars in the 2030s.

Sending man to Mars would mark the kind of exploratory breakthrough reminiscent of NASA’s glory days. Yet, try to think of a conversation you’ve had or even overheard about the mission. If you’re like me, you’ll come up empty.

I didn’t live through the 1960s, but my understanding is the moon challenge issued by President Kennedy, and America’s determined progress toward it in competition with the Soviets, was much more top of mind.

It’s not that NASA’s technological prowess is lacking. The images and information relayed back to Earth from the Curiosity rover on Mars, the Juno mission to Jupiter and the Hubble space telescope, among other missions, have often been breathtaking and ground-breaking. The problems to be overcome if a manned Mars mission is to succeed are numerous and daunting, yet NASA seems confident it can resolve them within the next two decades.

This may be more a matter of Americans’ studied and ever-greater retreat from the notion of national purpose.

As Yuval Levin documents well in his excellent 2016 book, “The Fractured Republic,” the 1950s and ’60s were a unique era regarding national unity. Americans were coming off several decades in which various forces — a pair of world wars, a depression, the rise of mass media — pushed them toward consensus politically, economically and culturally. Ever since, we have been moving in the opposite direction of individualization.

The ’50s and ’60s, Levin argues, represented a brief, perhaps unrepeatable moment when we retained enough of the consensus to get behind national initiatives while enjoying enough of the (small-L) liberalization to unlock the creativity and dynamism to achieve them.

Such as sending men to the moon.

The political ramifications of the fracturing he describes go well beyond the fate of NASA and its missions. But I wonder if we have lost the spirit of unity that propelled that age of exploration, and may be necessary for the next one.

One could imagine, for instance, President Trump pointing to Mars as a MAGA-worthy example of national greatness. And, just as easily, his critics on both the left and the right branding it as either committing ideological apostasy (cut spending!) or ignoring more pressing problems (butter, not rockets!) at home.

To bridge that divide might require not space travel, but time travel.