Can People Live Without Plants?

     Over the long term, people as well as animals cannot survive without plants.  They provide us with food, re-oxygenate the air, absorb carbon dioxide which helps the Earth’s atmosphere maintain thermal equilibrium—now at risk of imbalance from the excessive release of carbon dioxide--, clean pollutants out of dirty water, and stabilize soil with their roots to prevent erosion.  From the plants’ point of view, animals and humans are parasites.

     Those parasitic humans lucky enough to raise edible gardens in their back yards find September and October to be delicious months.  The pleasure experienced from picking and eating homegrown, vine-ripened tomatoes, cucumbers, zucchini, artichokes, cantaloupes, raspberries, grapes, pears and apples positively affects a profound psychological satisfaction in a human being.  There is a many millennia-old relationship between fertile soil and human gardeners.  That’s why people have harvest festivals, like Oktoberfest, to celebrate that ancient and recurring contentment with good food.

     Contrast this enjoyment of the fruits of the Earth with the situation of the six test subjects in the Mars-500 Experiment at the Moscow-based Institute for Medical and Biological Problems.  They are confined within a “set of windowless steel capsules” and live on canned food while pretending to be en route to and from Mars.  Canned food ought to keep them alive for five hundred plus days, but will they be able to cope psychologically with the deprivation of fresh fruits and vegetables for that long?

     Back in the 1980’s, a research group put together the Biosphere II Project near Tucson, Arizona to see if people could survive sanely in a sealed, artificial structure containing plants and animals.  If it worked, then such an environment would be a good way to live off-planet.  On December 27, 1988, my husband and I traveled to the Sun Space Ranch Conference Center to participate in a Biosphere II educational program.  The Biosphere II structure was still under construction.  We toured the building site, the temporary greenhouses and animal shelters with their collection of flora and fauna for the jungle, savannah, high desert, ocean, and farm biomes to be installed inside the Biosphere II.  These ecosystems would recycle the air, water and food for the human occupants for three years in the same way as they do it globally on the planet.  If the Biosphere II succeeded in Arizona, then space pioneers would want to build such mini-biospheres for themselves on the Moon, Mars and in large space structures at libration points in planetary or solar orbits.

     A few years after our visit to Biosphere II, a group of test subjects entered it and were sealed inside for the three-year experiment.  Unfortunately, a few months later, the group developed health problems when the oxygen level of the sealed structure gradually declined.  The researchers outside the Biosphere II strove valiantly to find the cause the of the oxygen depletion.  Eventually, the situation became dangerous and the experiment was halted as the occupants left the structure.  After months of analysis, the researchers discovered that the concrete in the structure’s floor and lower walls was still curing and absorbing more oxygen out of the sealed atmosphere than the interior plants could replace.  This was a valuable lesson that would not have been learned without running the simulation. 

     What will be the unexpected lessons learned from the Mars-500 Experiment in Moscow?  Can humans remain healthy and sociable for five hundred twenty days without the presence of plants and what they produce?  The people at the Antarctic Science Station near the South Pole cope with the long, harsh winters of bitter cold with only a small greenhouse of edible plants at their facility.  People on the ISS manage for six months with minimal resupplies of fresh food.  Even if the six test subjects in the simulated Mars mission make it to the five hundred and twentieth day, will a space ship without edible plants producing fresh air, clean water and fresh food be the best way to travel across the Solar System? 

Interplanetary ships do not need to be large replicas of a mini-Earth with jungle, savannah, high desert and ocean biomes; but, in my opinion, they do need to have ample edible gardens for human life support.  Where is the experimental project to find out how many and what kind of edible plants it takes to keep a human alive 24/7 and in touch with his or her ancestral and psychological link to fertile soil?  An exclusively artificial environment for humans may lead to madness.  There is a reason that humans seek green surroundings.  When we go to space to stay there, we need to bring plants with us.