Pictured here is the rocky and red surface of Mars.
While shielding crews from radiation is a primary concern of engineers, providing people with life supplies in flight is an area for biomedical specialists. In Russia specialists of the Institute of Biomedical problems (IBMP) have developed a concept for a closed-loop life-support system (LSS) for interplanetary voyages.
"There are three basic ways to provide a person with air during long-term spaceflight," said Vladimir Sychev, a Chief of IBMP Biological Life Support Systems Laboratory, in his exclusive interview with SPACE.com.
The first is to put a an oxygen tank and a CO2 absorber inside the spacecraft. The second is to disintegrate water through hydrolysis in order to get oxygen -- carbon dioxide will still have to be removed from the spacecraft by a physical-chemical CO2 absorber. The third way is to grow plants, which will generate O2 and absorb CO2.
"The latter, which is basically taking a piece of
biosphere into space, seems to be the most promising for long interplanetary flights," stressed Sychev.IBMP started working in this direction in the early 1960s. In 1961, the first experiment in a closed volume -- 176.5 cubic feet (5 cubic meters) -- was conducted when a man was put into a barrel with vegetation and lived there for a day.
From the mid 1960s through early 1980s, IBMP conducted six more experiments where a person lived for one or two months inside a closed volume, with life-support provided by single-cell alga and superior plants. The test subjects were provided with air, water and partly food.
"IBMP specialists have determined that 450 grams (16 ounces) of dry chrorella need to be photosynthesized to provide a person with a daily portion of oxygen and regenerated water," said Sychev. "If we talk about high plants, it will require15 to 30 square meters (161 to 323 square feet) to provide a person with a daily portion of life supplies. 15 meters will be enough to provide just oxygen. 30 meters if you also provide him or her with food."
The space greenhouse
A flight to Mars, which will take from one to two years, will require more from LSS than just oxygen generation and CO2 absorption.
"Crews during [a] journey that long cannot rely on periodical supplies of vitamin rich food from Earth," said Sychev. "A person should get raw vitamins with vegetables. Vitamin pills [are] not a solution. Nobody knows what will happen to them during long-term exposure to weightlessness and space radiation."
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For this reason IBMP started experiments with plants and vegetables in space in the early 1990s. "We came across a significant degree of skepticism on the side of our colleagues who did not believe in the success of such activities," said Sychev. "Since water feeding of the plants depends on the gravity, very few researchers believed that it would be possible to create a greenhouse in space."
Pictured above, the Lada greenhouse which will be installed in Zvezda module.
In 1990, Russian and Bulgarian specialists developed and built the Svet greenhouse for experiments with vegetation in outer space. Svet is a unique automatic laboratory designed to cultivate plants in weightlessness.
Svet was installed in the
Mir space station's Kristall module. The first experiment with lettuce and radishes lasted 54 days. Both vegetables grew much slower in space than on Earth and did not reach their regular size.Weightlessness or ethylene?
In 1995, a number of technological innovations principally developed by Russian and American specialists, were incorporated into Svet greenhouse. Thanks to these innovations an experiment with dwarf wheat conducted in 1997, turned out to be much more successful. Both the size and weight of plants were within their regular range, although none of the 300 ears contained a single grain.
Based on the analysis of the results of experiments, IBMP specialists suggested that the plants were affected by ethylene, which was present in the Mirs atmosphere. Both IBMP specialists and their U.S. colleagues from Utah State University then chose Apogee wheat, which turned out to be the least sensitive to ethylene.
In-orbit experiments with Apogee wheat were conducted by cosmonauts Gennady Padalka in 1998 and Sergey Avdeev the following year. All of the shoots produced grain and offspring. This is how IBMP researchers proved that the absence of gravity is no obstacle to normal plant development and growth.
Experiments with vegetation in space will be continued by IBMP in the newly developed greenhouse, which is to be installed in the
Zvezda module on the International Space Station. The traditional LSS wont be totally decommissioned
While a biological LSS seems to be the most adequate for a flight to Mars, Sychev believes that for the near future a biologically based life-support system should be combined with a traditional physical-chemical LSS. "It would make sense to create a hybrid system which would generate 70 percent of the oxygen through [a] physical-chemical LSS and 30 percent through [a] biological one. The latter will also regenerate 100 percent of [the] water. Thus, if one system starts losing its efficiency, another will compensate for this loss," said Sychev.
Other than providing crews with oxygen, water and fresh vitamins, a biological LSS could also remove micro-particles from the stations atmosphere. There are about 400 types of micro-particles in Mirs cabin air and ISS will probably have as many," said Sychev.
The future is close
Overall, according to Sychev, IBMP solved all conceptual problems of the creation of a closed-loop biological LSS as far back as in the 1980s, and is ready to develop this type of LSS for a concrete mission to Mars.
"If IBMP starts working in this direction today and it will also be provided with an adequate financing of about $500 million, the institute will create such system in five to seven years," said Sychev.
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