Interaction of physical-chemical and biological regeneration processes in ecological Life Support Systems.

Catalytic combustion of inedible biomass of plants in ecological Life Support Systems (LSS) gives rise to gaseous oxides (CO2, NO2, SO2, etc.). Some of them are toxic for plants suppressing their photosynthesis and productivity. Experiments with "Bios-3" experimental LSS demonstrate that a decrease of photosynthetic productivity in a system with straw incineration can jeopardize its steady operation. Analysis of the situation by a mathematical model taking into account absorption parameters of the system in terms of toxic elements makes it possible to formulate requirements for the structure and operation of LSS to provide for its stability. Avenues for further investigation of the problem of toxic stability of LSS are proposed.

Long-term experiments on man's stay in biological life-support system.

We describe the experimental system having maximal possible closure of material recycling in an ecosystem, including people and plants, which was carried out in a hermetically sealed experimental complex "BIOS-3", 315 m2 in volume. The system included 2 experimentators and 3 phytotrons with plants (total sowing area of 63 m2). Plants were grown with round-the-clock lamp irradiation with 130 Wm-2 PAR intensity. The plants production was food for people. Water exchange of ecosystem, as wall as gas exchange, was fully closed excluding liquids and gas samples taken for chemical analysis outside the system. The total closure of material turnover constituted 91%. Health state of the crew was estimated before, during and after the experiment. A 5-months period did not affect their health. The experiments carried out prove that the closed ecosystem of "man-plants" is a prototype of a life-support system for long-term space expeditions.

[Dynamics of the accumulation and retention of volatile organic substances released by bacteria]. / Dinamika nakopleniia i sokhraneniia letuchikh organicheskikh veshchestv, vydeliaemykh bakteriiami.

The object of this work was to study the production of volatile biologically active compounds by microorganisms and their accumulation in the medium in the course of several days. The inhibiting action of the accumulated volatile metabolites was found to depend on the time within which the culture was incubated and on the sensitivity of the test organism. The activity of the accumulated metabolites was shown to decrease with the time of storage. Several volatile compounds were found among the metabolites.

[Composition of a nutrient medium for the continuous cultivation of Thiobacillus ferrooxidans]. / Sostav pitatel'noi sredy dlia nepreryvnogo kul'tivirovaniia Thiobacillus ferrooxidans.

Thiobacillus ferrooxidans was found to require the following biogenous elements for constructing its biomass: phosphorus, 14 +/- 2; magnesium, 2 +/- 0.5; potassium, 5 +/- 1; nitrogen, 100 +/- 10 (milligrams per gram of dry biomass). It was shown that the concentrations of biogenous elements in the growth medium, which did not limit the biosynthesis, did not exceed 5 divided by 10 mg per litre for all of the studied elements. The medium 9K that is commonly used for growing Thiobacillus ferrooxidans has been found to differ significantly from the calculated one with the balanced ratio of biogenous elements.

[Express method of studying microorganism interaction on solid media]. / Ekspress-metod izucheniia vzaimodeistviia mikroorganizmov na tverdykh sredakh.

To study interaction of microogranisms on solid media, a method of agar plates with the use of replicators was elaborated and compared with that of perpendicular streaks and agar blocks. Apart from being a rapid one, the new method provides quantitative determination of the interaction of level of the microbes. The results of the method are reliable and easily reproduced. Out of the 3 procedures considered the method of agar plates is most sensitive and precise.

[Dependence of the rate of ferrous oxide oxidation by a Thiobacillus ferrooxidans culture on its concentration]. / Zavisimost' skorosti okisleniia zakisnogo zheleza kul'turoi Thiobacillus ferrooxidans ot ego kontsentratsii.

The effect of the concentration of ferrous iron on the rate of its oxidation was studied with Thiobacillus ferrooxidans. The specific rate of oxidation of ferrous iron was found to increase with its concentration and to decrease with a rise of the total iron content. Cultivation of bacteria with electrochemical reduction of Fe3+ produced high cell concentrations at a low content of total iron (4--6 g/litre), e. g. upto 4.5 g/litre (dry biomass weight).

[Dependence of the species makeup of a mixed culture of microscopic algae on the illumination and on the rate of nutritional element intake]. / Zavisimost' vidovogo sostava smeshannoi kul'tury mikrovodoroslei ot osveshchennosti i skorostei postupleniia élementov pitaniia

The existence of microalgal polycultures in a continuous culture is discussed. This depends on both physiological characteristics of algae and the rate with which nutrient elements are supplied. The routes of control of the species structure of the polyculture are discussed.

Life support system with autonomous control employing plant photosynthesis.

This research was aimed at obtaining a closed control system. This was achieved by placing all the technological processes providing for human vital activities within the hermetically sealed space, and by transferring the entire control and guidance of these processes to people inhabiting the system. In contrast to existing biological life support systems, man has been included not only as a participant of metabolism, but as an operator who is the central figure in collecting information, making decisions and controlling all technological processes. To tackle this problem, the "BIOS-3" experimental complex was created for performing long-term experiments using different structures of biological life-support system. The experiment lasted six months and consisted of three stages. During the first stage the system was comprised of two equivalent phytotrons with the culture of wheat and an assortment of vegetable plants, and the living compartment. At the second stage, one of the phytotrons was removed while a compartment of chlorella cultivators was introduced. The third stage differed from the second, the former using wheat phytotron and the latter employing phytotron with an assortment of vegetable cultures. Three men inhabited the system simultaneously. The experiment demonstrated that a biological life support system controlled autonomously from the inside is feasible within a small confined space. However, immunological and microbiological research shows, that the medium created by the system is not fully adequate for man. In conclusion, some prospects have been outlined for further studies of biological life support systems.

Theoretical and experimental decisions in the creation of an artificial ecosystem for human life support in space.

All of man's former space flights were not real ventures into space in the biological sense, as his life was supported with unregenerated earth supplies. The coming stage of space exploration requires man's long existence in the cosmos and on the other planets. This stage of man's activity outside the earth become possible only by creating small man-made ecosystems, permitting the support of his metabolism by the recycling of substances of the terrestrial biosphere. Creation of such systems is a new scientific and technical task. Man-made ecosystems are a new product of man's activity, which have no complete analogy, either in nature, or in technology. Stochastic mechanisms, which stabilize biogeocenosis, cannot be effective in small ecosystems. A technique of parametric control over biosynthesis made it possible to calculate, and put to practice, an ecosystem for man with a cyclic regeneration of the atmosphere, water and, partially, food. The specific bio-technological properties of small man-made ecosystems are being analysed. The possibility of their application for man's excursions into space and for the settlement of other planets is being considered.

Experimental biological life support system. II. Gas exchange between man and microalgae culture in a 30-day experiment.

The experiments of a prolonged stay by man in a closed atmosphere regenerated by a biological method have been examined. In the course of the experiment, a study of isolated and compatible links of a gas-closed system of "man-microalga" was carried out. The main emphasis was placed on the study of the biological compatibility of the links of the system and primarily of the effect of gaseous metabolites built up in the system of man. The dynamics of a number of physiological parameters of the man under experiment were studied. The regular functional tests of the respiratory and cardiovascular system were carried out. An electrocardiogram was made and respiratory rate and pulse were registered. Oxyhemogram investigations and laboratory clinical examinations were also performed, as well as some psychological tests. It was possible to equalize the respiratory gas ratio by the composition of the cultural environment for algae and by the nutrition ration of man. This eliminates time limit for the life maintenance system, especially on microalga photosynthesis. The results of the experiments permit drawing a conclusion on the biological compatibility of man and microalgae in their prolonged direct gas contact. Thus the possibility of obtaining a balanced atmosphere regeneration system on the basis of counterbalanced gas exchange between man and controlled photosynthesis of algae has been proven experimentally.

Experimental biological life support system. I. Continuous cultivation of algae as a link of a closed ecosystem.

According to the opinion of many researchers, a culture of microalgae may serve as a regenerator of atmosphere in the cabin of a spaceship. To use microalgae for these objectives, it was necessary to have an automatic unit possessing a high productivity of the cultivation process. This unit, containing a minimum of equipment, enables carrying on for an unlimited time the cultivation of algae without a drop in their productivity. The unit meeting these requirements (the cultivator) was developed by the authors and will be described in the presentation. The stability of the microalga photosynthetic system is characterized by the fact that after 70% biosynthesis repression by the ultraviolet radiation, a full regeneration of the productivity level takes place within 24 hours. In our experiments the system was functioning with the stable estimated productivity for many days (up to two months without interruption). During the process, no biological inhibitions to permanent performance and further prolongation of its life were found. As to the productivity, stability and control, the described biotechnological method may appear to be useful as a link of the closed ecosystem.