Press Release

Purdue to Help NASA Create Life-Supporting Ecosystem in Space

By SpaceRef Editor
March 12, 2002
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WEST LAFAYETTE, Ind. The National Aeronautics and Space Administration
announced today (Tuesday, 3/12) that Purdue University will head a center to
develop “advanced life support” technologies for sustaining human colonies
on Mars and elsewhere in space.

Purdue received a $10 million, five-year grant to lead the NASA Specialized
Center of Research and Training for Advanced Life Support. The center will
include 24 researchers from Purdue and two historically black universities,
Alabama A&M in Normal, Ala., and Howard in Washington, D.C.

The center’s director, Cary Mitchell, said Purdue will help design a
self-sustaining environment for future space colonies. Residents will grow
their own crops and live inside fully enclosed habitats in which all wastes
are constantly being recycled and purified. Plants will provide foods and
oxygen for humans, microbes will be used to break down wastes, and other
technologies will be needed to remove impurities from the air and water.

“There will be a closed-loop synergy, meaning the wastes of one system are
taken in, used and processed by another system,” said Mitchell, a professor
of horticulture at Purdue.

The habitats will be largely “bioregenerative,” meaning biological organisms
will help to sustain a life-supporting environment. But engineered systems
also will be critical in maintaining that environment. Various devices will
be needed to recycle air and human wastes and to purify dirty water from
bathing, dish washing and other sources.

“It’s exactly duplicating what happens on earth,” Mitchell said. “But to
make sure that things cycle fast enough, you need some physical and chemical
processes to help along the biological systems.”

Perhaps people will be living in such “biospheres” on Mars or the moon
within only a few decades, Mitchell added.

“Because Purdue is so strong in engineering and agricultural research, it is
the ideal institution to lead this kind of center,” said Purdue President
Martin C. Jischke. “Besides the exciting goals associated with human space
exploration, this effort also is very valuable for its potential social
impacts gained through educational outreach and developing partnerships with
minority universities.”

U.S. Sen. Richard Lugar, R-Ind., said this research is important for the
nation’s space program.

“This federal research grant for Purdue demonstrates the university’s
valuable role in ensuring that the United States continues to lead the world
in space-related research,” Lugar said. “I commend Purdue officials for
their hard work to secure funds for this worthwhile initiative and wish them
success in this endeavor.”

The NASA advanced life support center is the only one of its kind in the
nation. Purdue had led the center for five years beginning in 1990, when
Mitchell also was its director. Rutgers University has led research efforts
for the past five years. Purdue will again head the center as of Oct. 1, the
start of the next federal fiscal year.

“Although there have been differences in emphasis among the three centers,
they are all working toward the same goal: that of enabling self-sustaining
human colonization of planetary surfaces beginning during the late second or
early third decades of the 21st century,” Mitchell said.

Universities competing for the NASA center were encouraged to include a
minority university with expertise in the appropriate technical fields in
agriculture and engineering. Purdue selected not one, but two minority
universities as partners –one with exceptional engineering researchers and
the other with world-class agricultural scientists, Mitchell said.

“Purdue conducted a nationwide search for minority partners,” Mitchell said.
“We found the best engineers at Howard, and we found the best food
scientists and agriculturists at Alabama A&M.”

Research teams will integrate scientists and engineers from all three

Half of the center’s funding and efforts will be directed toward research in
waste management in space. Twenty percent will go toward systems analysis,
and another 20 percent is earmarked for food technology and biomass
production, which includes food crops. Ten percent will provide educational

The center’s associate directors, Purdue civil engineering professors James
Alleman and Kathy Banks, will oversee the solid waste management and
outreach projects, respectively. Banks also will lead research to develop an
air-and-water treatment system. Joseph Pekny, a professor of chemical
engineering at Purdue, will be in charge of the systems analysis portion of
the research.

Alleman said a key strength in the Purdue proposal to NASA was an emphasis
on interdisciplinary “team spirit.”

His research will focus on systems that break down human solid and liquid
wastes. Alleman is developing a “solids thermophilic aerobic reactor,” or
STAR, which will use bacteria inside a “reactor” to break down solid human
wastes. The bacteria will generate so much heat as they break down wastes
that the inside of the reactor will approach 90 degrees Celsius, or more
than 190 degrees Fahrenheit. Because the bacteria thrive in a hot
environment, they are said to be thermophilic, and because air will be
circulated through the reactor, the process is aerobic.

Alleman also is developing a system that freezes liquid wastes to remove the
salt and leave behind pure water crystals, enabling the salt to be strained
out. The technique consumes far less energy than other NASA attempts to
purify liquid wastes by boiling.

“It’s hugely more cost-effective from an energy point of view,” Alleman

Banks will lead the water and air treatment research team and is working to
design a single system called BREATHe, for bio-regenerative exhaust air
treatment for health. The system will purify both water and air by using

“This combined approach to air and water treatment has never been done
before,” Banks said.

The system uses microbes in “biofilms” to treat the air and so-called “gray
water,” or water that has been soiled from bathing, washing dishes and
similar uses.

“If you walk across a stream and you slip on a slimy rock, you just stepped
on a biofilm,” Banks said. “A biofilm is a gelatinous matrix, where the
microbes actually grow. Microbes excrete an extracellular polymer, and grow
in that slimy matrix. The matrix allows them to attach to surfaces.”

Banks’ research team will grow specialized biofilms on plastic devices, such
as spherical structures, through which air and water pass.

“The microbes will eat, actually degrade, the organic contaminants in the
water and the air,” Banks said.

Another Purdue researcher is designing a system that will use ultraviolet
light to further cleanse the air and water before it is used by the crew.

Other technologies will be needed to recycle plant wastes.

“The human inhabitants are going to be eating mainly a vegetarian diet,”
Mitchell said. “They are going to have a lot of crop waste — roots, stems,
leaves, things you don’t eat. Microbes will digest these wastes with natural

The plant wastes, which are inedible to humans, might be ground up and fed
to Tilapia fish.

“Thus, the mostly vegetarian diet will be supplemented by small but
important amounts of fish protein, which also will have important
psychological value for humans living for long periods of time in
confinement in space,” Mitchell said.

Scientists at Alabama A&M are studying the ability of fungi to degrade crop
waste that is inedible by humans, producing shitake, oyster and other exotic
mushrooms in the process.

Space diets might be more varied than some people would expect, said
Mitchell, who in addition to directing the center will be in charge of
research dealing with food production.

People living in space will grow a variety of crops, including legumes such
as cowpeas, peanuts and soybeans, and cereal crops such as wheat and rice.

“An important consideration in vegetarianism is to have a mixture of a
legume and a cereal,” Mitchell said. “Legumes and cereals are deficient of
certain amino acids, but if you put the two together, then you end up with a
protein that’s pretty good.”

Space faring farmers also will likely grow other foods, including herbs for
seasoning, potatoes and salad crops, such as tomatoes and lettuce.

“We will investigate energy-saving ways to light food crops in space using
vertical strips of colored, light-emitting diodes,” Mitchell said. “Light
strips will hang right in the crop stand with plants growing all around
them. These lights are cool enough that plants can even touch them. The
colors will match the absorbance of the photosynthetic pigments in the
plants. This is a modification of the commercial ‘pathlights’ you see in
movie theaters and in airline exit rows.”

Researchers are studying about 15 crops for possible use in the advanced
life support system. The work will address a range of issues.

“How are we going to store foods in space so they don’t degrade microbially
or get spoiled?” Mitchell asked. “How can we grow crops hydroponically,
because we are not going to be bringing soil with us? How are we going to
grow crops in a reduced gravity environment?”

The moon’s gravity is only one-sixth that of Earth’s, while Mars’ gravity is
slightly more than one-third as strong as Earth’s.

Sophisticated analytical models will be needed to properly design and
maintain the space habitats.

“For example, how much food-crop area do you need to grow to sustain a crew
of six people on Mars?” Mitchell said. “Since the crops will be putting out
oxygen that people need to breathe, you can’t have all the crops maturing at
once. When wheat turns brown it stops photosynthesizing and making oxygen.
So you’ve got to have everything staggered. You have to have growth curves,
models for each crop, and to stagger them so that there is a continuous
minimum amount of oxygen and then to provide a balanced diet.”

Pekny’s systems analysis component will develop mathematical models critical
to helping develop the best possible designs. Using models helps to reduce
the amount of experimentation needed by predicting how specific designs will
function before they are built.

“One function of the systems analysis group is to develop models of each of
the components of the advanced life support system and to hook them together
to make sure the system functions overall,” Pekny said.

Banks’ outreach component will strive to educate schoolchildren and the
general public about NASA research and the center’s work.

She will combine her outreach efforts with the Indiana Space Grant
Consortium, based at Purdue and directed by Barrett Caldwell, an associate
professor of industrial engineering. Space Grant is a group of universities
and institutions that works with schoolchildren, teachers, college students,
industry and museums to increase the public’s knowledge about science and
space exploration.

The outreach effort will include developing materials and programs for
lessons in the public schools.

Writer: Emil Venere, (765) 494-4709,

Sources: Cary Mitchell, (765) 494-1347,

Kathy Banks, (765) 496-3424,

James Alleman, (765) 494-7705,

Joseph Pekny, (765) 494-7901,


Tiny light strips, such as ones Cary Mitchell displays in his Purdue
University lab, may one day provide the growth source for plants grown and
consumed by astronauts during extended space missions. Mitchell, a professor
of horticulture at Purdue, is director of the NASA Specialized Center of
Research and Training for Advanced Life Support. (Agricultural
Communications photo by Tom Campbell)

A publication-quality photograph is available at


Kathy Banks, a professor of civil engineering at Purdue University, views a
“bio-trickle system” that is part of her work with NASA to develop advanced
life support technologies for self-sustaining space colonies. Banks is
designing a single system to treat both air and water, which has never been
done before. Her system is called BREATHe, for bio-regenerative exhaust air
treatment for health. The system will purify both water and air by using
microbes. (Purdue News Service Photo by David Umberger)

A publication-quality photograph is available at

Jeanne Norberg, director

Purdue University News Service

1132 Engineering Admin. Bldg.

West Lafayette, IN 47907-1132

Office: (765) 494-2096; Fax: (765) 494-0401

Pager: (765) 423-8662; Cell: (765) 491-1460

Home: (765) 449-4986

SpaceRef staff editor.