Long before mastering the mechanics of spaceflight, men imagined sending other men into the cosmos. Cicero, de Bergerac, Godwin, Poe, Verne, Wells: the tone of their tales was sometimes satirical, and the transportation methods varied—moon geese, a space cannon—but, generally, the gender of the space travellers did not. One exception is “Somnium” (Latin for “dream”), the astronomer Johannes Kepler’s treatise on the heliocentric universe disguised as a story, published posthumously, in 1634. In it, a teen-ager discovers that his mother has a celestial mentor, a daemon, whom she summons to take them to the moon. The daemon’s criteria for moon trippers are harsh: “We do not admit desk-bound humans into these ranks, nor the fat, nor the foppish,” he explains. But “dried-out old women” can make for good spacefarers, since “they are accustomed to riding goats at night, or pitchforks.” Witches, he means. It’s a joke, one that came back to haunt Kepler when his mother was accused of witchcraft.

Nearly four hundred years later, women are not quite as likely to be burned at the stake, but they still have extremely low odds of getting into space. Of the more than five hundred people who’ve so far made the journey, only sixty-one have been women (of these, forty-seven were American). The dawning era of private spaceflight is not proving to be especially inclusive, either. In February, Elon Musk’s aerospace company, SpaceX, tested its Falcon Heavy rocket, the company’s biggest to date, which is designed to carry massive payloads and have reusable parts. Afterward, in a column for the San Diego Tribune, the astrophysicist Alison Coil wrote about how disheartening it was to look at the cheering crowd of SpaceX employees and notice that it was a “sea of almost entirely white men.” (An Electrek report from 2016 showed that women made up only fourteen per cent of SpaceX’s workforce.) The Falcon Heavy’s payload, on that maiden launch, was a Tesla Roadster belonging to Musk, with a mannequin dubbed Starman in the driver’s seat. Though the mannequin was named for a David Bowie creation, his appearance was more macho than flamboyant: one of his arms was draped over the car door, in a gesture of the one-hand-on-the-wheel steering so beloved of men in convertibles. “Every object humans have launched into the solar system is a statement,” the space archaeologist Alice Gorman wrote, in a piece about SpaceX’s iconography, after the launch. “Each tells the story of our attitudes to space at a particular point in time.” The photograph of Starman in Musk’s midnight-cherry Roadster, Gorman suggested, could qualify as the first “dick pic” taken in space.

For me, the image recalled a scene in Tom Wolfe’s 1979 paean to the Mercury Seven, “The Right Stuff,” in which the military test pilots turned astronauts race Corvettes and Maseratis at Cocoa Beach, in between bouts of carousing with “young juicy girls with stand-up jugs and full-sprung thighs and conformations so taut and silky that the very sight of them practically pulled a man into the delta of priapic delirium.” Only John Glenn refrained, both from the womanizing and the sports-car mania, which made him the butt of the others’ jokes. One morning, when the others reported for duty in the Astronaut Office, they found a cautionary message on the blackboard: “Definition of a sports car: A hedge against the male menopause.” Glenn may have written this, but he wasn’t as enlightened when it came to the question of who should go to space. At a congressional hearing, in 1962, on whether women should be allowed to join the astronaut corps, he testified that they should not. “It is just a fact,” he said. “The men go off and fight the wars and fly the airplanes and come back and help design and build and test them.”

Musk’s Starman followed in the footsteps of earlier test-dummy men: there was Ivan Ivanovich, a life-size mannequin who flew in a Vostok capsule a month before Yuri Gagarin became the first person to venture into space, in 1961; and SuitSat-1, a spacesuit repurposed, in 2006, as a satellite, and nicknamed Mr. Smith; and Mannequin Skywalker, who was sent up, in 2017, in a test of the New Shepard rocket designed by Jeff Bezos’s space company, Blue Origin. The few female avatars who’ve made it into space have done so with breasts exposed. One of the experimental V-2 rockets created for Hitler, in 1942, by S.S. Major Wernher von Braun—who, after the war, was poached by America to jump-start the space program—bore a logo from a popular German science-fiction film, “Frau im Mond”: a naked woman in high-heeled boots, sitting on a crescent moon, straddling a rocket. (When von Braun was asked, in the sixties, about the possibility of female astronauts, he made a sly joke about them being “recreational equipment.”) In 2016, when Richard Branson unveiled Virgin Galactic’s second SpaceShipTwo, its side displayed an eerily similar image: Galactic Girl, a space-age incarnation of the big-chested woman who graces some of Branson’s Virgin Atlantic airplanes. Blond and lily white, Galactic Girl is also supple: she seems to be doing a backbend in a strapless spacesuit, showcasing how perky her bosom is in zero gravity. (She was allegedly designed to resemble Branson’s mother, Evette, when she was young.)

Astronaut culture has always thrived on exclusivity. In the earliest years of the space age, during the Cold War, the high status of astronauts was linked to who was barred from the applicant pool—it would have dented the prestige of spaceflight, for both Soviets and Americans, if it were so simple that a woman could do it. “The exclusion of women and racial minorities from the pioneering astronauts corps of the 1950s and 1960s was a deliberate gesture,” De Witt Douglas Kilgore argues in his book “Astrofuturism: Science, Race, and Visions of Utopia in Space,” from 2003. Musk and his fellow-“astropreneurs” talk about democratizing space travel; Branson has said that his company’s goal is to make space accessible, because “by doing that we can truly bring positive change to life on Earth.” In this view, the fastest way to get more women into space is by backing space-tourism startups, trusting that they will open the cosmos to the masses (once the super-wealthy have had their fun). But it’s not enough to promise women that one day they, too, could become passengers to space. As Ryan Jenkins, a Cal Poly ethicist who writes about emerging technologies, told me, “democratization is not only about access but about input. Who is able to guide and shape these activities?”

In “Space Barons: Elon Musk, Jeff Bezos, and the Quest to Colonize the Cosmos,” Christian Davenport tells the backstories of the billionaires who are vying for control of the emerging NewSpace industry. In addition to Musk and Bezos, Davenport writes about Branson and Paul Allen, the co-founder of Microsoft and an early investor in new spaceflight technologies. The members of the quartet are so similar in type that their biographies, as Davenport relates them, start to blur into one. As boys, they mostly read the same science fiction. (Musk has said that his favorite Robert A. Heinlein novel is “The Moon Is a Harsh Mistress,” which is set on a lunar colony where young girls marry men and women are either homemakers or work at beauty shops or brothels.) The space barons were all outsiders as young men; they’re all obsessed with rockets; they all want, more than anything, to win. Their space ventures are supposedly driven by a common goal of elevating or saving humankind, but they don’t always treat others humanely.