Living Off the Land

Biosphere / by Lee Billings /

The same technology that keeps astronauts alive in outer space could foster more sustainable lifestyles right here on Earth.

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To make matters worse, one crop alone can’t be a self-sufficient life-support system—an entire artificial ecology must be constructed and maintained for long periods of time, complete with all its delicate biochemical checks and balances. This is a task so daunting we’ve never quite achieved it even down here on Earth, though not for lack of trying. Space agencies around the world have mounted numerous hermetically sealed ecological experiments over the years, attempting to sustain human life without relying on our planet’s natural ecosystem services. None have been unqualified successes—outside inputs inevitably are needed. Artificial ecosystem research at NASA, which led the field during the 80s and 90s, has now diminished to a trickle. Rather than develop sustainable ways to live on the Moon or Mars, the agency is struggling to simply get there.

Today, the best hope for advanced life-support systems is probably the European Space Agency’s Micro-Ecological Life Support System Alternative (MELiSSA) project. In development for almost two decades, MELiSSA is seeking to “close the loop” between the production and consumption of metabolic nutrients by recycling and reusing solid and liquid organic waste with 100 percent efficiency. That is, the MELiSSA team hopes to create a self-sustaining system that turns urine, feces, and other unsavory byproducts into vegetables, potable water, and fresh air.

To transmute sewage into supper, the project uses a mix of high-tech physicochemical and biological approaches spread across five compartments, which, according to MELiSSA’s top coordinator, Christophe Lasseur, are modeled on the ecosystem of a lake.

A lake bottom covered with anaerobic sludge inspired MELiSSA’s first compartment, where bacteria feed on solid waste and release nutrients. Just above the lake bottom, light filters in but the water is still low in oxygen. Red algae thrives here, breaking down carbon compounds. This portion of the lake is similar to compartment two. Compartment three is akin to the shallows near the lake’s surface, where oxygen is plentiful and nitrifying bacteria convert the ammonia in urine into ammonium, a potent fertilizer. Compartment four is like the surface of the lake, where carbon dioxide, sunlight, and nutrients are plentiful and photosynthetic organisms clean the water and produce oxygen and food. The crew is the final step of the process: They live in compartment five, consuming the oxygen, water, and food to create waste that enters the cycle anew.

In June the project reached a milestone with the inauguration of the MELiSSA Pilot Plant at the Universitat Autònoma de Barcelona in Spain. Over the next several years, the Pilot Plant will test the MELiSSA loop on a “crew” of 40 lab rats, which collectively require roughly the same amount of oxygen as one person. If these early tests are successful, the system will eventually be enlarged for human testing, but that event may be even further in the future than the next Moon landing.

In the meantime, the technology that may one day support human life on the Moon or Mars is being put to good use right now in Earth-bound economies. Research from the University of Guelph has been used extensively in the agricultural industry for many applications, including decreasing chemical run-off and boosting productivity in greenhouses. The water-recycling work at NASA Ames can reduce water requirements for laundering clothes and has inspired emergency-survival products now used by the US military. Offshoots of MELiSSA’s technology are used in Europe to process wastewater and monitor the quality of sparkling wine.

Off-planet, “green” lifestyles aren’t just fashionable, they’re required. Any eventual residents of a lunar base or Martian habitat will almost certainly be vegetarians, and thrift will be crucial for survival. “You must strive to recycle virtually every atom of everything that you’ve brought with you,” Dixon says. “And the technology required to achieve that is exactly what we need here on Earth to reduce our environmental imprint and create more sustainable ecosystems, all so we can manage to survive here a bit longer than we otherwise might.”

If NASA or other space agencies ever develop and deploy sustainable artificial ecosystems elsewhere in our solar system, they will essentially be extending our biosphere beyond the confines of a single planet, an event as profound as when creatures first crawled from the Earth’s primordial seas to gradually colonize the land.

Still, no plant has ever even germinated on any body in the solar system other than Earth. But that soon may change. Two private companies, Odyssey Moon and Paragon Space Development, are planning a robotic mission to land a mini-greenhouse filled with soil and mustard seeds on the Moon by 2014. Bathed in sunlight for the duration of the Moon’s 336-hour day and monitored from Earth via high-definition video, the mustard seeds would have just enough time to sprout from the soil and flower before lunar night falls. It would be a feat extravagant, symbolic, and hauntingly beautiful—just one small step toward a giant leap that may someday come.

Originally published July 20, 2009

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Tags engineering environment space technology

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