The newscaster said, "Eugene Cernan, the last man to walk on the moon …" and I understood from the elegiac tone that the next phrase would be "… has died." He was 82, and no one has been to the moon since 1972. Isaac Asimov, Robert Heinlein, Ray Bradbury and other giants of classic science fiction are spinning in their graves. The moon? Are you kidding me? NASA once planned to land a human on Mars by 1986. Bradbury had us there in '99. I felt the same spike of sadness and nostalgia I experienced when Sally Ride, the first American woman in space, died in 2012.

I had no personal connection to Ride, but word of her death cast a pall. We were almost precise contemporaries. I arrived on the planet 15 days before she did in 1951, and when she made her historic voyage on the space shuttle Challenger in 1983, I was envious.

She was a Renaissance woman — a brilliant student at Stanford who earned degrees in English and physics, before receiving a doctorate in the latter; a tennis player of sufficient quality and grit that Billie Jean King assured her a professional career was within her grasp; a risk-taker who took a flier in responding to a recruitment ad for the astronaut corps that 8,000 others also answered. She was one of 35 chosen.

As with Gene Cernan, my funk was triggered by the death of a symbol — in her case, the youngest person to enter Earth orbit, even while lacking the elite military credential of jockeying jet fighters. She fulfilled the promise of the sometimes prescient science-fiction writers of our youth, the prophets of the Space Age who painted the future in exuberant primary colors, vibrant with possibility. She represented the generation bound for the stars. In an interview, Ride once said of space travel: "It's who we are." Or at least, perhaps, who we aspired to be.

In the early 1960s, as Russian and American pioneers launched the first daring expeditions beyond our atmosphere, ramping up the stakes in steep bursts of technological prowess and gambles, I remember speculating — inspired by Heinlein — that surely a Space Academy would be established by the time I graduated from high school in 1969, and I intended to matriculate.

Alas: no, not, never. But I did receive a draft card courtesy of the Selective Service System, offering a potential opportunity to explore the wild inner spaces of Vietnam and Cambodia, and sadly, that card was not necessarily an anomaly for a "space cadet." NASA, after all, was the epitome of the "military-industrial complex" that President Dwight Eisenhower had warned us about in his farewell address of Jan. 17, 1961. "The potential," said Ike, "for the disastrous rise of misplaced power exists and will persist." The rockets that blasted Sally Ride toward heaven were originally invented to satisfy Dr. Strangelove, intercontinental mass death and the shareholders of aerospace giants. Actualizing Ray Bradbury's "Martian Chronicles" was, at best, spinoff. After beating the Soviet Union to the moon, we drifted away, refocusing on spacefaring machines.

Sally Ride was a California girl, and when she died I thought of another Californian, Eric Hoffer. He was a migrant farm laborer, dishwasher, gold prospector and longshoreman who evolved into a writer and thinker. His seminal book, "The True Believer," was published the year Sally and I were born. It's a historical page-turner created by a self-educated seeker. He was almost a celebrity in the 1960s, his arrival signaled by being parodied in MAD Magazine. Some nabobs of the intelligentsia snubbed him as "that primitive philosopher," but "Believer," dissecting the traits of mass movements, still resonates — just substitute some of the "isms" and names of particular demagogues. It remains as fresh as Donald Trump.

Hoffer was skeptical of the baby boomers — not of our dreams of space and our devotion to Capt. Kirk and the Starship Enterprise, but to our communal rejection (for a time) of what made possible the achievement of Sally Ride. Hoffer's vision of humanity was one of complete dominion, the hostile Earth transformed into cities, farmland and parks, where nature was a strictly indentured servant. The so-called counterculture activated by the Vietnam War caused him to note: "Many of the young … have been made aware of the possibility of a nuclear holocaust from the day they were born. They see the poisonous mushroom cloud as nature's retaliation against the violators who stole her secrets. The [current] ecological fervor is probably the manifestation of an urge to propitiate nature … the young's attitude toward nature should fill us with foreboding. On this savage continent, anyone who sides with nature against man — as many of the wilderness boys do — ought to have his head examined."

Hoffer spent most of his working life outdoors — wet, cold, hungry, underpaid, struggling against the adversarial elements. Born around 1900, his appreciation for the "web of life" was underdeveloped until old age, and comments before his death (in the year Ride went into space) display a gentler view of "the wilderness boys," but he understood the conflict: the military-industrial-rocket-complex of the Space Age vs. Mother Earth, the "Monkey Wrench Gang" and the Age of Aquarius.

Three years after Ride's first trip, the Challenger exploded, killing seven of Sally's colleagues, and she was appointed to the presidential investigation commission. It boiled down to human inattention and arrogance revolving around an O-ring gasket, but the program survived, even to a bit beyond the fiery demise of Columbia in 2003. Today, the formerly second-place Russians are the only link for human travel to the International Space Station, an artifact that appears to be the final outpost of people in space for the foreseeable future.

"The Martian Chronicles," a collection of short stories by Ray Bradbury, was first published in 1950, seven years before the Sputnik launch. In one tale, the fourth human expedition to Mars, set in June 2001, safely lands. The previous three have vanished. The astronauts discover that Mars had supported a sentient humanoid race that built a magnificent civilization thousands of years old, but they were all dead, killed by chickenpox, thus proving that at least one of previous human expeditions had survived long enough to transmit the disease. The archaeologist of the crew becomes enthralled by the Martians. He deciphers their books, admires their art, plays their music. He "goes native" and begins killing his colleagues, hoping to prevent or delay the eventual destruction of Mars and its legacy.

The rest of the crew fights back and corners him. Under a white flag, the captain approaches the archaeologist and urges surrender. In response, the rebel offers him a glimpse of Martian history and philosophy. He says, "They stopped where we should've stopped a hundred years ago … . They knew how to live with nature and get along with nature. They didn't try too hard to be all men and no animal." In a word, they didn't attempt to dominate Mars, and they built no spaceships.

It is well, perhaps, that we planet remodelers haven't returned to the moon or plowed on to Mars. The dreams of the 1960s are dead. The passing of Sally Ride and now Gene Cernan may serve as coda to that particular music of the spheres. But we do require a new dream. Our future might devolve to simple survival of the species — a popular dystopian science fiction theme — and while that may be motivational, it's hardly inspiring. In the frontispiece of "The Martian Chronicles," Bradbury wrote: " 'It is good to renew one's wonder,' said the philosopher. 'Space travel has again made children of us all.' "

It did indeed, at least for many of my generation, but what will we wonder at now? I won't presume to dictate a collective dream, but mine encompasses "the fierce green fire" that Aldo Leopold saw in the eyes of a wolf; "the clearest way into the universe" that John Muir recognized in undisturbed forest; "the singing wilderness" that Sigurd Olson heard along the waters of the North; "the ever flowing stream of time, the beginning and the end" that Rachel Carson perceived in the oceans. And I can even heed that consummate practical earthling Eric Hoffer, who mused on the pages of his diary in 1974: "Why should not the Occident stop for awhile — stop growing, working, consuming, wasting … . A dramatic end of the fossil fuel age could be the opening act in the renewal and rebirth of the Occident. The balance of the century should be devoted to the search for cheaper and cleaner fuels … and use its manpower in a concerted effort to cleanse air and water of pollution, replenish the soil, reforest the hills, and clean up the cities."

It's a start. Mars can wait. Our machines are already there, and can hold our place. Or take it. They are suited to space travel and do not require an ecosystem. You can imagine the computer-generated voice: "Humankind, an ascendant species since the end of the Pleistocene … ."

Peter M. Leschak, of Side Lake, Minn., is the author of "Ghosts of the Fireground" and other books.