Closed Life Support Systems Research Articles

Reproduction in the Space Environment

Mankind's exploration and colonization of the frontier of space will ultimately depend on men's and women's ability to live, work, and reproduce in the space environment. This paper reviews animal studies, from microorganisms to mammals, done in space or under space-simulated conditions, which identify some of the key areas which might interfere with human reproductive physiology and/or embryonic development. Those space environmental factors which impacted almost all species included: microgravity, artificial gravity, radiation, and closed life support systems. These factors may act independently and in combination to produce their effects. To date, there have been no studies which have looked at the entire process of reproduction in any animal species. This type of investigation will be critical in understanding and preventing the problems which will affect human reproduction. Part II will discuss these problems directly as they relate to human physiology.

Reproduction in the Space Environment

Mankind's exploration and colonization of the frontier of space will ultimately depend on men's and women's ability to live, work, and reproduce in the space environment. This paper reviews animal studies, from microorganisms to mammals, done in space or under space-simulated conditions, which identify some of the key areas which might interfere with human reproductive physiology and/or embryonic development. Those space environmental factors which impacted almost all species included: microgravity, artificial gravity, radiation, and closed life support systems. These factors may act independently and in combination to produce their effects. To date, there have been no studies which have looked at the entire process of reproduction in any animal species. This type of investigation will be critical in understanding and preventing the problems which will affect human reproduction. Part I1 will discuss these problems directly as they relate to human physiology.

Analysis of an algae-based cellss: Part 1: Model development

A steady state chemical model and computer program have been developed for a life support system and applied to trade-off studies. The model is based on human demand for food and oxygen determined from crew metabolic needs. The model includes modules for water recycle, waste treatment, CO 2 removal and treatment, and food production. The computer program calculates rates of use and material balance for food, O 2, the recycle of human waste and trash, H 2O, N 2, and food production/supply. A simple non-iterative solution for the model has been developed using the steady state rate equations for the chemical reactions. The model and program have been used in system sizing and subsystem trade-off studies of a partially closed life support system.

Analysis of an algae-based celss: Part 2: Options and weight analysis

Life support components are evaluated for application to an idealized closed life support system which includes an algal reactor for food production. Weight-based trade studies are reported as “breakeven” time for replacing food stores with a regenerative bioreactor. It is concluded that closure of the life support gases (oxygen recovery) depends on the carbon dioxide reduction chemistry and that an algae-based food production can provide an attractive alternative to re-supply for longer duration missions.

Air revitalization compounds: A literature survey

Chemical processes for air revitalization are attractive alternatives for some closed life support systems in the applications of space and marine explorations. A review of the literature is given for the purpose of evaluating potential candidates as air revitalizing chemicals based upon a set of criteria including toxicity in use, removal of airborne contaminants and bacteria, theoretical oxygen yields, chemical reactivity to breathing atmospheres, and commercial availability. The preliminary evaluation shows potassium and sodium Superoxides as prime candidates for further evaluation against the practical considerations of actual use. Upon closer scrutiny, potassium Superoxide is the desired chemical for air revitalization in closed life support systems according to the present technology. Kinetic reaction rates for the simple hydration of KO2 were reported to increase for increasing pressures to 12 atm making it a promising air revitalization chemical at the hyperbaric conditions encountered in deep diving.

Dynamic considerations for control of closed life support systems

Reliability of closed life support systems will depend on their ability to continue supplying the crew's needs in the face of perturbations and equipment failures. These dynamic considerations interact with the basic static (equilibrium) design through the sizing of storages, the specification of excess capacities in processors, and the choice of system initial state (total mass in the system). This paper uses a very simple system flow model to examine the possibilities for system failures even when there is sufficient storage to buffer the immediate effects of the perturbation. Two control schemes are shown which have different dynamic consequences in response to component failures.

Balanced Aquatic Microcosms: Their Implications for Space Travel

Data are summarized showing that the course of diurnal metabolism in several different types of balanced aquatic microcosms tends to follow the same pattern. Both net photosynthesis and nighttime respiration are maximal in the first half of the light or dark periods. This phenomenon also occurs in natural balanced aquatic communities. The importance of this metabolic pattern to closed life support systems of an ecological nature is pointed out, and ways of avoiding adverse effects to astronauts are suggested.

Open Sequence Components of a Closed Ecology

Among the items necessary for life support in a closed ecological system designed for space travel one may list oxygen, water, food, and energy. The production of oxygen for breathing has apparently been claimed by photosynthologists, and the production of drinking water by a variety of engineers. Acceptable food for the space man, while it should be within the province of food technology, has been almost totally neglected by this and other groups. Considerations of energy in closed ecosystems have been made to some extent by everyone. Both speculations and calculations outlining the character and placement of the probable members of closed life support systems have been made repeatedly. Myers (1960), Bowman (1953), Konecci (1959), Brockman et al., (1958), and Tischer (1960) are examples. More recently attention has turned to a consideration of methods suitable for the modification and degradation of human wastes for use by subsequent members of the system. Chapman (1960) has employed an activated sludge process to reduce the COD of human wastes by as much as 90% in 24 hours of treatment. Others have used more or less conventional waste treatment methods employing bacteria and algae while Tischer (1962) has used thermophilic bacteria, hypochlorite digestion, and electrochemical degradation. Research in this laboratory has provided information on several microorganisms and methods which might find use in the ultimate closed ecology. It is the purpose of this discussion to describe some of these and to comment on their utility.