The next question is evident: How big a bottle closed to outside
flows, filled with what kind of living organisms, would you need to
support a human inside?
When human daredevils ventured beyond the soft bottle of the Earth's
atmosphere, this once academic question took on practical meaning. Could
you keep a person alive in space -- like shrimp in an Ecosphere -- by keeping
plants alive? Could you seal a man up in a sunlit bottle with enough
living things so that their mutual exhalations would balance? It was a
question worth doing something about.
Every school child knows animals consume the oxygen and food that plants
generate, while plants consume the carbon dioxide and nutrients that
animals generate. It's a lovely mirror, one side producing what the
other needs, just as the shrimp and algae serve each other. Perhaps the
right mix of plants and mammals in their symmetrical demands could
support each other. Perhaps a human could find its proper doppelganger
of organisms in a closed bottle.
The first person crazy enough to experimentally try this was a Russian
researcher at the Moscow Institute for Biomedical Problems. In 1961,
during the heady early years of space research, Evgenii Shepelev welded
together a steel casket big enough to hold himself and eight gallons of
green algae. Shepelev's careful calculations showed that eight gallons
of chlorella algae under sodium lights should supply enough oxygen for
one man, and one man should generate enough carbon dioxide for eight
gallons of chlorella algae. The two sides of the equation should cancel
each other out into unity. In theory it should work. On paper it
balanced. On the blackboard it made perfect sense.
Inside the airtight iron capsule, it was a different story. You can't
breathe theories. If the algae faltered, the brilliant Shepelev would
follow; or, if he succumbed, the algae would do likewise. In the box the
two species would become nearly symbiotic allies entirely dependent on
each other, and no longer dependent upon the vast planetary web of
support outside -- the oceans, air, and creatures large and small. Man and
algae sealed in the capsule divorced themselves from the wide net woven
by the rest of life. They would be a separate, closed system. It was by
an act of faith in his science that a trim Shepelev crawled into the
chamber and sealed the door.
Algae and man lasted a whole day. For about 24 hours, man breathed into
algae and algae breathed into man. Then the staleness of the air drove
Shepelev out. The oxygen content initially produced by the algae
plummeted rapidly by the close of the first day. In the final hour when
Shepelev cracked open the sealed door to clamber out, his colleagues
were bowled over by the revolting stench in his cabin. Carbon dioxide
and oxygen had traded harmoniously, but other gases, such as methane,
hydrogen sulfide, and ammonia, given off by algae and Shepelev himself,
had gradually fouled the air. Like the mythological happy frog in slowly
boiling water, Shepelev had not noticed the stink.
Shepelev's adventuresome work was taken up in seriousness by other
Soviet researchers at a remote and secret lab in northern Siberia.
Shepelev's own group was able to keep dogs and rats alive within the
algae system for up to seven days. Unbeknownst to them, about the same
time the United States Air Force School of Aviation Medicine linked a
monkey to an algae-produced atmosphere for 50 hours. Later, by parking
the tiny eight-gallon tub of chlorella in a larger sealed room, and
tweaking the algae nutrients as well as the intensity of lights,
Shepelev's lab found that a human could live in this airtight room for
30 days! At this extreme duration the researchers noticed that the
respirations of man and algae were not exactly matched. To keep a
balance of atmosphere, excess carbon dioxide needed to be removed by
chemical filters. But the scientists were encouraged that stinky methane
stabilized after 12 days.
By 1972, more than a decade later, the Soviet team, directed by Josepf
Gitelson, constructed the third version of a small biologically based
habitat that could support humans. The Russians called it Bios-3. It
housed up to three men. The habitat was crowded inside. Four small
airtight rooms enclosed tubs of hydroponically (soil-less) grown plants
anchored under xenon lights. The men-in-a-box planted and harvested the
kind of crops you might expect in Russia -- potatoes, wheat, beets,
carrots, kale, radishes, onions and dill. From the harvest they prepared
about half of their own food, including bread from the grain. In this
cramped, stuffy, sealed greenhouse, the men and plants lived on each
other for as long as six months.
The box was not perfectly closed. While its atmosphere was sealed to air
exchanges, the setup recycled only 95 percent of its water. The Soviet
scientists stored half of their food (meat and proteins) beforehand. In
addition, the Bios-3 system did not recycle human fecal wastes or
kitchen scraps; the Bios-dwellers ejected these from the container,
thereby ejecting some trace elements and carbon.
In order not to lose all carbon from the cycle, the inhabitants burned a
portion of the inedible dead plant matter rendering it into carbon
dioxide and ash. Over weeks the rooms accumulated trace gases generated
by a number of sources: the plants, the materials of the room, and the
men themselves. Some of these vapors were toxic, and methods to recycle
them unknown then, so the men burned off the gases by simply "burning"
the air inside with a catalytic furnace.
NASA, of course, was interested in feeding and housing humans in space.
In 1977 they launched the still-going CELSS program (Controlled
Ecological Life Support Systems). NASA took the reductionist approach:
find the simplest units of life that can produce the required oxygen,
protein, and vitamins for human consumption. It was in messing around
with elemental systems that NASA's Joe Hanson stumbled on the
interesting, but to NASA's eyes, not very useful shrimp/algae combo.
In 1986 NASA initiated the Breadboard Project. The program's agenda was
to take what was known from tabletop experiments and implement them at a
larger scale. Breadboard managers found an abandoned cylinder left over
from the Mercury space shots. This giant tubular container had been
built to serve as pressure-testing chamber for the tiny astronaut
capsule that would spearhead the Mercury rocket. NASA retrofitted the
two-story cylinder with outside ductwork and plumbing, transforming the
interior into a bottled home with racks of lights, plants, and
Just as the Soviet Bios-3 experiments did, Breadboard used higher plants
to balance the atmosphere and provide food. But a human can only choke
down so much algae each day. Even if algae was all one ate, chlorella
only provides 10 percent of the daily nutrients a person needs. For this
reason, NASA researchers drifted away from algae-based systems, and
migrated toward plants that provided not only clean air but also
Ultra-intensive gardening seemed be what everyone was coming up with.
Gardening could produce really edible stuff, like wheat. Among the most
workable setups were various hydroponic contraptions that delivered
aqueous nutrients to plants as a mist, a foam, or a thin film dripping
through plastic holding racks matted with lettuce or other greens. This
highly engineered plumbing produced concentrated plant growth in cramped
spaces. Frank Salisbury of Utah State University discovered ways to
plant spring wheat at 100 times its normal density by precisely
controlling the wheat's optimal environment of light, humidity,
temperature, carbon dioxide, and nutrients. Extrapolating from his field
results, Salisbury calculated the amount of calories one could extract
from a square meter of ultradensely planted wheat sown, say, on enclosed
lunar base. He concluded that "a moon farm about the size of an American
football field would support 100 inhabitants of Lunar City."
One hundred people living off a football field-size truck farm! The
vision was Jeffersonian! One could envision a nearby planet colonized by
a network of Superdome villages, each producing its own food, water,
air, people, and culture.
But NASA's approach to inventing a living in a closed system struck many
as being overly cautious, strangulatingly slow, and intolerably
reductionistic. The operative word for NASA's Controlled Ecological Life
Support Systems was "Controlled."
What was needed was a little "out-of-control."