“The political will to keep spaceflight going just doesn’t exist anymore, hasn’t for a long time,” she writes. On the contrary, what doesn’t exist anymore is the political will to kill human spaceflight, even if NASA is adrift in purpose: The agency’s plans for future rockets presently have powerful bipartisan support in Congress, as they have had for years, though little consensus exists on programmatic goals or optimal budget levels. The post-shuttle generation of space transportation is already waiting in the wings, with NASA’s heavy-lift Space Launch System and crew-carrying Orion spacecraft in intensive development. Meanwhile, several private companies are building smaller, cheaper human-rated rockets of their own. Even if none of this were occurring, the truth is the nation could readily repurpose military rockets such as the Atlas V and the Delta IV to launch humans into space if desired. Dean’s strong claims call for strong repudiation: No, we are not leaving orbit. No, these are not the last days of American spaceflight. Unless, that is, these are the last days of America — which would be the topic of a different book.

Even so, there is much here to like and even love. The book is a joy to read if you can overlook the author’s excessive pessimism. Dean, an associate professor of English at the University of Tennessee, clearly adores NASA’s human space program. She has also written a novel based on the Challenger disaster, and for “Leaving Orbit,” she traveled to the Kennedy Space Center in Cape Canaveral, Fla., to witness the last three shuttle launches. She describes her experiences in superb prose that is perhaps the next best thing to being there. Astronauts freshly returned to Earth readjusting to gravity wear “an expression of a child shaken from a happy dream,” and shuttles are seen launching from afar in “silent-film majesty.” Buzz Aldrin, the second man to walk on the moon, makes a marvelous extended cameo. Dean even manages to squeeze in a pocket history of spaceflight that links the launches at Cape Canaveral with the 19th-century writings of Jules Verne and the 16th-century explorations of Ponce de León.

Throughout the book, however, her main focus isn’t really on the scenery, or the spacecraft, or “the unutterable awe of American heroes stabbing into the heavens on columns of fire,” but rather on “the people who knew the shuttles best,” the rank-and-file workers at Kennedy whom she interviews and occasionally befriends. The small details in the stories Dean tells about these individuals as they shepherd the shuttles through their last launches and landings are often enlightening and sometimes heartbreaking, like the time she encounters a wall in the launch control center lined with plaques for each and every shuttle mission, save for the two that never came home. The wall is in a restricted area far from public access, yet the two empty spaces are still discolored from the countless reverent touches of passing NASA employees. These are people, the story suggests, who love and live for spaceflight with all their hearts and souls.

And, despite rejecting the book’s central premise, I often found myself agreeing with the deep truths Dean elegantly conveys about America’s space program. Why is it that the shuttle program is ending? In part, Dean notes, it’s because large numbers of Americans mistakenly believe NASA consumes huge fractions of the federal budget, when in fact its allotment is about 0.4 percent. The Wall Street bailouts of 2008 consumed more funds than NASA has during its entire existence. “Uneasiness about the cost of spaceflight has always been paired with widespread positive feelings about spaceflight,” she writes. “Spaceflight is an achievement we take great pride in, paid for with our own money, over our objections.”