What Will Humans Really Need in Space?

We won’t truly know until we’re there.

Illustration of an astronaut partially adrift in a room filled with tentacle-like leek plants.
Erik Frobom

An architecture professor who studies space settlements responds to “Space Leek” by Chen Quifan.

In 1975 at the NASA Ames Research Center, two groups of experts had a disagreement about the purpose of bringing plants to space. NASA had brought together a team for something that it referred to informally as a “Summer Study.” These short, intense sessions with academics, engineers, and designers were intended to address specific issues in space exploration. One, in 1971, was about the Search for Extra-Terrestrial Intelligence, or SETI. Another, in 1980, was about using self-replicating machines for space manufacturing. The 1975 study was on the design of large-scale space settlements. These would be located, like the Yutu-3 space station in Chen Qiufan’s story, at the Earth-moon Lagrangian points where gravity between these two bodies allows for stable orbits. Unlike the Yutu-3 (or as the characters in the story call it, the Roast Garlic), these were not intended to be purely research stations. They would be home to about 10,000 people engaged in the work of building solar-powered satellites.

The team realized that these people would need to bring, or make, all of the things they needed themselves. Everything about the habitat would have to be planned. The urban planners recognized that these habitats would be as densely populated as cramped cities. So people would need open planted spaces, like parks and plazas, to help relieve the stress. The agriculturalists knew that it was important for these habitats to grow their own food. The planners thought that residents could use the farms as parks, places to unwind and relax. But in order to maximize crop yields, the agricultural scientists wanted their farms to have 24-hour sunlight, constant high heat, and atmospheres overloaded with humidity and CO2. A plant paradise is a human hell, not a relaxing garden. In these designs, there are two different attitudes about the purposes of plants and planted spaces, and they’re not easily reconciled. In space, everything humans bring or make has to have some specific reason to be there, but as Chen’s story shows, sometimes those reasons are more complicated and unknown than we think.

Animals and plants have been in space for longer than humans have. Americans sent seeds to space in the 1940s, to test the effects of radiation exposure. The second successful artificial satellite launch ever, the Soviet-made Sputnik-2, carried an animal passenger, the famous Russian dog Laika. Sadly, her mission was not designed for her to survive more than a few hours, and she became the first earthling to die in space. Since then, other, more careful attempts have been able to launch all kinds of animals and plants, and to bring them home safely. The next set of problems to solve were about reproduction and growth. Several experiments in the early 21st century have shown that it is possible for plants to germinate, sprout, and even flourish in the high radiation, zero-gravity conditions aboard the International Space Station. Russian crews on the ISS have been growing and, to take things to the next step, eating their own crops since 2003, but it wasn’t until 2015 that the Americans tried it too, with a head of space-grown romaine lettuce.

But long-term living in space will depend on more than salad. Beyond the survival and growth of individual plants and animals, living in space would require, as the team that worked on the 1975 summer study knew, whole ecosystems. For purposes of efficiency and variety, some plants in the 1975 scheme would feed agricultural animals, and the waste from these farm animals would, along with human waste, become fertilizer for the next generation of plants. In this plan, humans and their animals would be part of a circle of life that could endlessly recycle CO2, oxygen, nutrients, and water in a self-sustaining way. In 2019, Chinese space scientists landed the Chang’e 4 lander on the moon’s far side. This lander contained an important experiment—one of the first attempts to create a closed ecosystem in space. The Lunar Micro Ecosystem module on the lander contained planted seeds, yeast, and fruit fly eggs. The ecosystem was maintained for nine days, and it only failed when a heating system was unable to keep the interior temperature high during the two-week long lunar night.

Chang’e is the name of the moon goddess that is accompanied by the rabbit Yutu, in the same mythology that gives the space station in Chen’s story its name. And Chang’e 4 also brought along a rover, Yutu-2. At the time of this writing, a real rabbit in the moon is exploring the lunar surface. The 1975 summer study recommended bringing rabbits to outer space as well. They, along with chickens and fish, would be a crucial protein supply in this closed cycle ecosystem for the space settlement’s residents. Altogether, in the plans from the summer study, there would be 37 times as many animals as humans in these habitats. The disagreement between the botanists and the urban designers in the summer study story, and the breakdown in the Chang’e 4 Micro Ecosystem, shows how difficult it can be to make closed artificial environments that are comfortable for different types of organisms.

Chen’s Space Leek, and the resonant mythology that informs it, are an illustration that there will always be other reasons to bring other life to space, whether we know it or not. In the story, the botanist Shengnan has an emotional attachment to her leeks, even though it has been brought to space as a research subject, while the chemist Jing has her eye on the leek for other, more culinary reasons. The true value of the leek crop’s presence turns out to be more than scientific or gastronomical—it has chemical and material properties that can save the station, and their lives. This life-saving potential is only revealed through the sentimental power of the mythology that animates the story. Like Yutu, the rabbit in the moon, Shengnan grinds the leek with a mortar and pestle, and makes it into an elixir of life. The value of the leek, and the value of the myth, had not been measurable or predictable in advance.

In any space settlement scenario, human existence will depend on more than just the number of square meters devoted to park space or farmland, or the mass of protein and carbohydrates available from agriculture. The things we bring and make will have value that’s not immediately quantifiable. People will have houseplants, almost definitely, and even pets. Pets, like rabbits, enrich human life in ways that are other than nutritious. The first rabbit in space was Russian, named Marfusha. She orbited and returned back to Earth two years before Yuri Gagarin’s historic human flight. As the sometime-caretaker of pet rabbits, I would no more want to see them become food than I would one of Laika’s kin. As humans figure out how to live in space and embed themselves in complex sensitive biological systems, the nature of the environments, their contents, and the parameters within them will have to be closely studied and carefully specified. Stories like Chen’s are good reminders that it’s sometimes necessary to remember the myths and the sentiments along with the numbers.

Future Tense is a partnership of Slate, New America, and Arizona State University that examines emerging technologies, public policy, and society.