§ 6.7 NASA CELSS Work

There are many projects funded by NASA on CELSS, "Advanced Life Support", and life sciences in space.

NASA BioHome

In 1989, NASA completed a small facility called BioHome, which integrated "biogenerative" components for recycling air, water and nutrients from human wastes -- into a single, integrated habitat. Maximum air closure was achieved, and experiments were begun, which continue to date.

A little larger than a mobile home, the facility put living quarters in a compartment beside the crops and waste processing facilities, circulating air and water between them. Drinkable water was taken from air condensate.

The facility initially focussed on wastewater treatment. Aquatic and semi-aquatic plants known for their ability to process sewage were studied. These were not edible plants, but were instead aquatic and semi-aquatic plants chosen for their history in making excellent compost material for food plants, after they grow based on the sewage. After growing to a certain size, they are harvested, cleaned and composted. This compost has been used as a complete growth media for tomatoes, sorghum, corn, potatoes, cucumbers and squash. The facility grew edible plants, though that information was not available on the web at the time of this writing.

PVC pipes slowly moved sewage downstream. The pipes had holes cut in them in which the plants were emplaced. Experiments measured the effectiveness of several plants, each of which can utilize raw human sewage as a complete growth media.

Samples of the water were taken at different points in the flow and studied.

In the end, the effluent water flowed through an ultraviolet unit to assure complete kill of all microorganisms, especially those pathogenic to humans. This water was then suitable for use in toilets and watering plants.

Drinking water came from condensate from the air (e.g., dehumidifier and air conditioner condensate), which was also disinfected by ultraviolet equipment. The plant leaves emitted quite ample supplies of water vapors.

It was also found that the plants purified the air of many manmade substances such as formaldehyde, benzene, toluene and other undesirable organics. Foliage plants were placed throughout the living quarters for absorbing the gases from the newly constructed and furnished facility.

"When sewage is slowly filtered through an aquatic plant root filter system, complex biological processes take place during wastewater treatment and purification. The symbiotic relationship that is normally established betweeen the plant roots and microorganisms living on and around these roots is very complex and important in the wastewater treatment process... This process not only removes organic chemicals, but is also thought to contribute to the reduction of other polluting substances including pathogenic bacteria and viruses. It has been shown that roots of aquatic plants such as bulrush, reed, soft rush and water iris excrete substances that can either partially or completely kill pathogenic bacteria while not harming beneficial bacterial The aerobic zone around the aquatic root system can also support, in addition to bacteria, the growth of large numbers of protozoa which feed on bacteria, viruses and particular organic matter."

(paper reference: Wolverton et al.)

NASA CELSS Breadboard Project

The most aggressive CELSS project to date is the NASA CELSS Breadboard Project, initiated in 1986 and continuing beyond today.

This project is very well covered on the internet, with leads given below. However, before one jumps to that site and its contractors sites, it may be good for the layman to read our overview so that you don't lose sight of how things fit into the big picture. Some subprojects of the Breadboard Project are covered much better than others due to the different levels of effort of the various contractors as regards reporting on the web, which leaves the overall picture a little out of balance on the web as a whole.

The CELSS Breadboard Project has concentrated most of its research on growing crops in environmentally controlled chambers to optimize food productivity. Its initial goal was to demonstrate the feasibility of constructing and successfully operating on the ground a CELSS capable of meeting the life support requirements of one person. Most of the initial research and development focussed on existing experience and technology, with little attention to innovative or new technology. Indeed, much of the initial work was verifying that previous small laboratory studies could be scaled up.

The core of the initial phase was construction of a "Biomass Production Chamber (BPC)", a sealable large steel chamber approximately 3.5 meters in diameter and 7.5 meters high, with two floors, each floor having multiple racks and lamp banks, duct work for air flow, and various equipment for controlling temperature and humidity. Total chamber plant growing area is 20 square meters.

Wheat, soybeans, potatoes, sweetpotatoes, strawberries, rice, peanuts, radishes and other foods were grown in the facility.

Adjacent laboratories were used for converting wastes into plant nutrients, plant fertilizer, carbon dioxide and water. Some of the inedible biomass was converted into alternate food products, e.g., conversion of cellulose to sugar using enzymatic conversion.

At every stage, careful and detailed measurements of many kinds were made in order to understand the processes in depth.

Part of the CELSS Breadboard Project is funded through the John F. Kennedy Space Center, at http://atlas.ksc.nasa.gov/celss/celss.html

Part is also funded through the Johnson Space Center, at http://pet.jsc.nasa.gov/alssee/demo-dir/ihome.html

Links to subcontractors are well covered in the two NASA sites.

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