The astronauts aboard the ISS (or, as the jargon has it, "on station") will eat food grown in space today. Despite the 50 year history of crewed space flight, the consumption of space lettuce represents the first time this has ever happened. This is now all over the science press, and the image used to accompany the story links is usually the one above. This Whole Foods in space has nothing to do with the ISS experiment, it was a rendering commissioned by NASA to illustrate possible concepts for growing food on Mars. The real garden on the ISS is barely bigger than a kitchen cabinet, and looks very different. Plants do not use the green parts of the sunlight spectrum, so if they are grown with artificial light, it saves energy to leave that piece of the spectrum out, making for an eerie purple light that looks strange to human eyes, the lettuce loves it. The difference between these two images reveals a lot about our preconceptions and the need for familiar things we take with us when we think about leaving the Earth and making new worlds.
In the 1970s, NASA brought together artists, planners, architects, ecologists, and other specialists to think about this on a scale that's hardly been approached before or since. The Summer Study team's mandate was to design self sustaining colonies (NASA preferred to call them "settlements") for 10,000 people and up, the largest were several miles long. Especially at the low end of these dramatically large scale objects, the question of human population density and carrying capacity is key when every bit of available open space must be manufactured from scratch. What are the social, material, nutritional, and psychological needs of a large human population, and how much room does all of the stuff that supports those needs take up.
For example, how much park land is necessary to keep people sane and healthy? If they can't ever really leave the habitat without a mobile life support system, then in one sense, they are always indoors. In cities, parks have historically been a way to mitigate the stress of being completely surrounded by a hardscaped built environment all of the time. In the report, entitled Space Settlement, and published by NASA in 1976, the planners on the team examined large cities from around the world and came up with a healthy minimum of park square foot per person, and then they cut that number in half. The residents of these structures, they reasoned, won't need as much park land because there will also be other planted areas, devoted explicitly to agriculture, that they can also have access to. This is a rendering of one of those agricultural zones, painted by artist Rick Guidice.
In, one likes to picture, another conference room across the hall at the Summer Study, the agriculture experts were running their own numbers, and these ended up in the NASA report, too. The studied the maximum yield on record for various staple crops from around the world per square foot of farm, then they took that figure and doubled it. In the controlled environment of the habitat, they decided, conditions could be made ideal for growing crops year round. CO2 levels could be raised to twice what they are on Earth, and temperature and humidity levels could be kept at a maximum, so that the plants could flourish in abundant, nonstop sunshine. If pests or disease started to look like a problem in one area, then that area could be opened to vacuum and sterilized before any infection could spread. So the area that the urban designers were relying on for supplemental parkland would be, if the ecologists had their way, a carbon dioxide choked sweltering sunlit hell for humans, but a paradise for plants. The habitats in the NASA report appear to have been designed to these parameters, without resolving this contradiction.
This is not a story about the failure of design team members from different disciplines to crosscheck their assumptions … okay, it kind of is, but it's also a story about our own human-centric assumptions about what qualities a world should have. As anthropologist Michael Oman-Reagan has written, the interesting problem in thinking about space colonization is that right away we come hard up against this question of "what constitutes a world in the first place?" But also, we find that a related question asks "a world for who?" If we make a plant utopia, it's unlikely it will be a popular site for stir crazy humans to take weekend strolls. There's also another implication in this story, if plants don't see the color green, and the love to breathe the CO2 that's poison to us and changes the climate in ways we find dangerous - then have plants and humans ever even occupied the same world in the first place? Instead of the popular conception that we somehow share our world with other species, what the situation is more unstable than that? Instead of a clearly bounded sphere, we have something more like a shifting multidimensional Venn diagram, where some conditions are agreeable to all parties involved, but not by much, and not for long.