Eric Lafforgue / Art in All of Us / Corbis via Getty

Recently, NASA released colorful, dreamy illustrations depicting an imagined future in which human beings have made it to other worlds. A curly-haired astronaut floats inside a lunar space station, with the crater-pocked moon behind her. A lunar explorer steadies a camera on a tripod to photograph Earth in the distance. And an astronaut stands on the dunes of Mars with her hands in the pockets of her spacesuit, a dog at her side.

Wait, a dog?

NASA

To be clear, NASA’s ambitious plans for missions to the moon and Mars do not include dogs. (At least, none that the public knows about. If you’re a member of a top-secret program to groom doggonauts, please contact me.) The agency does want to send humans there, sometime in the 2030s.

But dogs have been to space. In the 1950s and 1960s, the Soviet Union strapped dogs into capsules and launched them into the sky. The canines were not trusty space sidekicks, but research subjects, strays collected from city streets to test launch systems before humans themselves did. (The United States conducted similar tests, with several species of monkeys.)

Engineers “trained” the dogs; they dressed them in spacesuits, kept them in small boxes for days, and put them through rocket-launch simulators. But any pup would do, really. In the fall of 1951, days before his scheduled flight, Bolik the dog somehow managed to run away. Russian engineers, facing a strict deadline, went outside, found a stray, and strapped him in. They named him ZIB, a Russian acronym that stood for “substitute for the vanished Bolik.” He completed the mission and returned to Earth safely.

That was a sub-orbital flight, though, which stops short of looping around the Earth. The first dog to truly go to space was Laika, a three-year-old perky-eared mutt, in 1957. Her capsule successfully made it to orbit and remained there for about five months, circling the globe, before plunging back into Earth’s atmosphere. But Laika didn’t survive. A safe return was never part of the plan. The capsule was designed to run out of oxygen within a week. According to sensors embedded beneath her skin, Laika’s heartbeat was triple the normal rate during launch, and her breathing frantic. She died not long after, likely because of the extreme temperatures in the overheated capsule.

Over time, other dogs orbited the Earth and returned alive. Eventually, so did people. Dogs were left on the ground, safe from the threat of being shot into the sky.

But the NASA poster suggests that, unlike the Soviet dogs, a canine on Mars would not be a lab animal, but a valued companion on the journey to a distant land. Even still—imagine life for a dog on Mars. It probably would be miserable.

The journey would begin with a bone-chattering rocket launch. Passengers would feel as much as four times the force of Earth’s gravity pressing down on them. The experience is stressful—even some of the best-trained astronauts take off with skyrocketing heart rates. It would be far worse for a passenger who couldn’t comprehend what was going on, says Clive Wynne, a psychology professor at Arizona State University who studies canine behavior, and the author of the forthcoming book Dog Is Love: Why and How Your Dog Loves You.

Wynne considered his own dog, Xephos, an eight-year-old mutt named for Xenophon, an ancient Greek scholar who wrote about dogs. “I’m pretty certain Xephos doesn’t want to go to Mars,” he says. “If we were to try this out by putting her in a confined space and subjecting her to loud noises and sudden movements, I think she would convince us that this wasn’t something she wanted to do.”

Xephos enjoys some turbulence, like riding in a car with the windows down. “If the option existed for a dog to stick its snout out the window during the ride to Mars, then maybe,” Wynne says. But “the little I know about space travel—there are not going to be windows.”

No, there won’t. And the technology to build a palatial spaceship like the USS Enterprise is many years away. The first ships to travel to Mars will likely be small and cramped, packed with little more than the essentials, like life-support systems. There won’t be much room for astronauts to move around, much less play catch with their canine companion.

The ride would be hard on the bodies of the passengers, human and dog alike, especially if their spacecraft can’t produce artificial gravity that keeps their feet and paws on the floor. Without gravity, fluids in the body would float to their heads and congest them. Bones and muscles would thin out. Eyeballs would squish, blurring vision—a medical mystery scientists are still trying to figure out. And without the protection of Earth’s magnetic field, the passengers would be exposed to radiation, the high-energy rays that permeate the cosmos, which can increase the risk of cancer.

Human beings can volunteer for this perilous experience, but their dogs can’t. “I think it would be inhumane to take a dog on a spaceship,” Wynne says.

The challenges would continue on Mars, if humans and their dogs even make it there. The air in the thin atmosphere is unbreathable and the soil toxic. The gravity, about one-third that of Earth, would wreak still more havoc on their bodies. The dog would probably live in a small habitat along with the humans, only venturing outside in a spacesuit.

Designing a spacesuit for a dog wouldn’t be the hard part (leaving aside the debate over how a dog would wear pants back on Earth). NASA has decades’ worth of experience in manufacturing spacesuits, which are like little spacecraft of their own, equipped with the systems necessary to keep their wearers healthy and alive. Presumably, the dog would communicate with a human companion the same way two astronauts chat during spacewalks: radio. The pup would wear a fabric hat featuring a microphone at the ear, to receive commands and who’s-a-good-dog reassurances, and another microphone at the mouth, so that the human companion could hear it bark. (NASA’s name for these hats—Snoopy caps—is quite appropriate.)

The problem is the dog’s experience inside that spacesuit, which would circulate the same air over and over. Dogs have 300 million olfactory receptors in their noses, compared with just 6 million for humans. They love to sniff just about everything in sight. They can even tell when their humans feel sick. The enclosed environment of a spacesuit would be stifling.

“The dog is never going to sniff the roses,” Wynne said. “There’s not going to be any weather. The dog is never going to smell the fresh rain and splashing puddles, and never going to sniff a lamppost and realize there’s a new dog in town.”

With their sense of smell limited, dogs wouldn’t be as useful, since working dogs are trained by scent. Perhaps they could be taught to sniff out certain minerals in the soil, but the investigation would have to be done with samples brought indoors, far from the Martian breeze, where machines could probably do it anyway.

There’s also the question of the dog relieving itself. Astronauts wear adult diapers during spacewalks; Mars explorers would have to train their canine companions to become comfortable with a similar arrangement. “I don’t know how anyone’s going to scoop the poop,” Wynne says.

Future generations of Martian dogs, born and raised on the barren planet, would probably be fine. Like children born on Mars, they wouldn’t miss the roses or the rain. But if it’s going to be this bad for the first canines, why send dogs to Mars at all?

“I’d assume we’d take our dogs and chickens and all sorts of animals with us, don’t you?” says Valeri Farmer-Dougan, a psychology professor at Illinois State University, where she runs the Canine Behavior and Cognition Laboratory. “When we traveled to other places over the course of human history, we took things with us.”

For owners who consider their pets family, it would no doubt be difficult to leave a loved one behind on Earth. “I wouldn’t want to go anywhere without my dogs,” says Farmer-Dougan, who has five: a golden retriever—her service dog—a poodle, and three special-needs Australian shepherds, two of which are deaf and blind. Sending people to an entirely new planet, decision makers would have to weigh the benefits of companionship and emotional attachment against ethical concerns about animal welfare.

Some Mars evangelists suggest that the rosy future pictured in NASA’s posters would emerge right after arrival. In a recent Popular Mechanics interview, for instance, Elon Musk was asked for his ideas for producing food, water, and fuel. “Once you get there, that stuff is relatively straightforward,” he said.

That’s quite optimistic. The first Mars missions will likely be perilous and painful. It would be tremendously difficult to keep the humans alive, let alone the dogs that come along. Astronauts would be better off bringing small machines, the common companions of space travels in science fiction. Research has shown that robots can prompt feelings of empathy and bonding in humans, especially when they look like WALL-E. They can roam the Martian landscape for hours, unencumbered by memories of an earthly past.

Wynne has another suggestion.

“I wonder if maybe it would be a better plan to take a cat,” he says.

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