Human Population Growth and Excess Consumption: Understanding Limits of Stable Functioning and Algorithms of Control Utilizing CELSS Technologies and Developments (Integrated Applied Modeling)

In order to pursue space colonization, long duration spaceflight, and human missions to Mars, we will need closed ecological life support systems which provide sustainable use of limited resources. While such systems are in various stages of development, we lack knowledge regarding the functional stability of closed ecological life support systems (CES) for long-duration space missions. Our global Earth Biosphere CES functioning is based upon statistical regulations, which are provided by planetary buffers. All current deviations caused by human activity are currently absorbed by these ‘planetary buffers’. Man-made Closed Ecosystems function at the limits of their natural stability due to insufficient buffer capacities and thus needs to be replaced or supplemented by other more appropriate control approaches. Previous research has indicated that purposeful control from human can increase stability levels if specific algorithms compatible to natural mechanisms are applied. Theoretical analysis is being done on data obtained in different Closed Ecosystems and has been shown that certain limits of functional stability exist for each specific system in terms of average material cycle rate and range of fluctuations. These limits are determined by: the system’s buffer capacities, the slowest (basic) material cycle in the system, natural structure of the circulating chemical elements cycles and Human Factors material load. Numerical estimates are provided for carbon cycles and it has been shown that stability of cycles in man-made ecosystems are more than a thousand times less than for global planetary cycles. Human Control could increase this low level of stability tremendously, but requires a certain level of understanding for closed material cycles development inside each specific system. This presentation will primarily discuss interactions between smallscale human crews and the available limited resources required for a CES functioning. Since there are limited resources in a CES, instead of continuously increasing consumption as would be possible in an unlimited environment, self-sustainable behaviors/activities must be practiced. This paper will address the limitations for human adaptation in a space environment and how to optimize human and environment interaction in a CES. Applications to manned space exploration will be considered in the context of understanding human motivation.

The effects of light intensity on three sweetpotato cultivars [Ipomoea batatas (L.) Lam] were evaluated in growth chambers, as part of NASA's Closed Ecological Life Support Systems (CELSS) program for long duration space missions. Vine cuttings of `TI-155', `GA Jet', and TUJ1 were grown using nutrient film technique (NFT) in a modified half Hoagland's solution with a 1:2.4 N:K ratio in channels (0.15×0.15×1.2 m). Plants were exposed to irradiance levels of 360 or 720 umols m-2s-1 with an 18/6 photoperiod in a randomized complete block design with two replications. Temperature was set at 28:22 lightdark and RH was 70%. Differences in plant response to were more related to cultivars than the effect of light intensity. Storage root number (8) fresh, (786 g/plant) and dry weights (139 g/plant) were highest for `TI-155' while foliage fresh and dry weights were highest for `TUJ1' when averaged across light levels. TI-155' (921 g/plant) and `GA Jet' (538 g/plant) produced greater yields at higher irradiance. `TUJ1' produced a higher yield (438 g/plant at the lower intensity compared to 219 (g/plant) at the higher intensity, suggesting this cultivar could produce storage roots in similar conditions in a CELSS.

Albumin Regeneration for Extracorporeal Liver Support Using Prometheus: A Step in the Right Direction

Selecting the appropriate atmosphere for a spacecraft and mission is a complicated problem. NASA has previously used atmospheres from Earth normal composition and pressure to pure oxygen at low pressures. Future exploration missions will likely strike a compromise somewhere between the two, trying to balance operation impacts on EVA, safety concerns for flammability and health risks, life science and physiology questions, and other issues. Life support systems and internal thermal control systems are areas that will have to respond to changes in the atmospheric composition and pressure away from the Earthlike conditions currently used on the International Space Station. This paper examines life support and internal thermal control technologies currently in use or in development to find what impacts in design, efficiency and performance, or feasibility might be expected. Understanding these changes should be helpful in producing better results during future trade studies or mission analyses.

<div class="htmlview paragraph">This paper considers the design of a life support system for transit to Mars and return to Earth. Because of the extremely high cost of launching mass to Mars, the Mars transit life support system must minimize the amount of oxygen, water, and food transported. The three basic ways to provide life support are to directly supply all oxygen and water, or to recycle them using physicochemical equipment, or to produce them incidentally while growing food using crop plants. Comparing the costs of these three approaches shows that physicochemical recycling of oxygen and water is least costly for a Mars transit mission. The long mission duration also requires that the Mars transit life support system have high reliability and maintainability. Mars transit life support cannot make use of planetary resources or gravity. It should be tested in space on the International Space Station (ISS). The oxygen and water recycling systems developed for the ISS are adequate for Mars transit but all have not yet been used on ISS and none were designed for the much higher mass launch costs and reliability requirements of Mars transit. Significant time and development effort, including long duration testing on ISS will be needed to provide the high quality oxygen and water recycling system that is needed for Mars transit.</div>

Spacecraft human life support systems can achieve ultra reliability by providing sufficient spares to replace all failed components. The additional mass of spares for ultra reliability is approximately equal to the original system mass, provided that the original system reliability is not too low. Acceptable reliability can be achieved for the Space Shuttle and Space Station by preventive maintenance and by replacing failed units. However, on-demand maintenance and repair requires a logistics supply chain in place to provide the needed spares. In contrast, a Mars or other long space mission must take along all the needed spares, since resupply is not possible. Long missions must achieve ultra reliability, a very low failure rate per hour, since they will take years rather than weeks and cannot be cut short if a failure occurs. Also, distant missions have a much higher mass launch cost per kilogram than near-Earth missions. Achieving ultra reliable spacecraft life support systems with acceptable mass will require a well-planned and extensive development effort. Analysis must determine the reliability requirement and allocate it to subsystems and components. Ultra reliability requires reducing the intrinsic failure causes, providing spares to replace failed components and having graceful failure modes. Technologies, components, and materials must be selected and designed for high reliability. Long duration testing is needed to confirm very low failure rates. Systems design should segregate the failure causes in the smallest, most easily replaceable parts. The system must be designed, developed, integrated, and tested with system reliability in mind. Maintenance and reparability of failed units must not add to the probability of failure. The overall system must be tested sufficiently to identify any design errors. A program to develop ultra reliable space life support systems with acceptable mass should start soon since it must be a long term effort.

<div class="htmlview paragraph">This paper addresses the effect of waste processing on advanced life support (ALS) system design. Waste processing is a critical component of an advanced life support system. It must take all life support system wastes and either convert them into useful products or into a form in which they can be discarded. Waste can be treated as soon as it is produced, stored as is, or processed into an intermediate form for further treatment. The decisions made will affect the cost-effectiveness of the system. Strategies must be developed to meet waste processing requirements for specific mission scenarios.</div>

<div class="htmlview paragraph">The purpose of dynamic modeling and simulation of Advanced Life Support (ALS) systems is to help design them. Static steady state systems analysis provides basic information and is necessary to guide dynamic modeling, but static analysis is not sufficient to design and compare systems. ALS systems must respond to external input variations and internal off-nominal behavior. Buffer sizing, resupply scheduling, failure response, and control system design are aspects of dynamic system design. We develop two dynamic mass flow models and use them in simulations to evaluate systems issues, optimize designs, and make system design trades. One model is of nitrogen leakage in the space station, the other is of a waste processor failure in a regenerative life support system.</div> <div class="htmlview paragraph">Most systems analyses are concerned with optimizing the cost/benefit of a system at its nominal steady-state operating point. ALS analysis must go beyond the static steady state to include dynamic system design. All life support systems exhibit behavior that varies over time. ALS systems must respond to equipment operating cycles, repair schedules, and occasional off-nominal behavior or malfunctions. Biological components, such as bioreactors, composters, and food plant growth chambers, usually have operating cycles or other complex time behavior. Buffer sizes, material stocks, and resupply rates determine dynamic system behavior and directly affect system mass and cost. Dynamic simulation is needed to avoid the extremes of costly over-design of buffers and material reserves or system failure due to insufficient buffers and lack of stored material.</div>

This report describes a flexible, reliable, deep space life support system design approach that uses either storage or recycling or both together. The design goal is to provide the needed life support performance with the required ultra reliability for the minimum Equivalent System Mass (ESM). Recycling life support systems used with multiple redundancy can have sufficient reliability for deep space missions but they usually do not save mass compared to mixed storage and recycling systems. The best deep space life support system design uses water recycling with sufficient water storage to prevent loss of crew if recycling fails. Since the amount of water needed for crew survival is a small part of the total water requirement, the required amount of stored water is significantly less than the total to be consumed. Water recycling with water, oxygen, and carbon dioxide removal material storage can achieve the high reliability of full storage systems with only half the mass of full storage and with less mass than the highly redundant recycling systems needed to achieve acceptable reliability. Improved recycling systems with lower mass and higher reliability could perform better than systems using storage.

Estimating CO2 gas exchange in mixed age vegetable plant communities grown on soil-like substrates for life support systems

Short- and long-term reliability of language fMRI

Design considerations of local controller for ITER coil power supply with high availability and reliability

<div class="htmlview paragraph">Successful operation of life support systems for human exploration of space will depend largely on in situ sensors and integration of these sensors to an autonomous control architecture. The complexity of a life support system demands that these sensors be uniquely qualified for a number of specific applications. Such applications may require multifunctional monitoring of the sensor environment and intelligent interaction with other sensors and control elements. In situ sensors found in the chemical processing industry are largely not multifunctional and not necessarily selected for minimal weight, volume and power demand. Therefore, the state-of-the-art for in situ sensors found in the chemical processing industries is not directly transferrable to life support applications. Highly autonomous life support systems require reliable chemical, physical and biosensors requiring little maintenance and which are highly fault-tolerant. These sensors will operate in a hierarchical network involving distributed databases, prediction models, rule-based reasoning modules for hypothesis generation and verification, controllers and final control elements. This paper discusses the limitations of the state-of-the-art for in situ sensors and argues in favor of a program of adaptation and enhancement of off-the-shelf sensor technologies and of research and innovation to develop more appropriate sensor technologies for life support systems. This paper also discusses briefly the desirable characteristics of smart sensors for life support applications and presents some preliminary concepts for hierarchical integration of in situ sensors and control elements.</div>

CELSS transportation analysis

BLSS: A contribution to future life support