FEMME: a precursor experiment for the evaluation of bioregenerative life support systems

<div class="htmlview paragraph">Study of bio-regenerative life support system is a critical issue for long term manned spaceflight applications. An engineering approach of such systems, consists in experimental stoichiometry and growth kinetics determination and building up structured and predictive mathematical models, in order to test simplified biological processes. Up to now, the main results obtained by such an aproach are in good agreement with ground-based data.</div> <div class="htmlview paragraph">Despite several scientific experiments performed in space, results on microbial kinetics study remains rare, and the real influence of space environment (micro-gravity, radiation, light spectrum, ..) on micro-organisms growth is still not quantified. Precursor space missions are therefore justified to expand current knowledge and check for the changes affecting such biological processes.</div> <div class="htmlview paragraph">In the framework of ESA Bioregenerative Life Support Systems research program, the FEMME experiment (First Extraterrestrial Man Made Ecosystem) is proposed to study scientific and technical parameters within space environment. In this paper, a description of the preliminary concept will be given. FEMME is an autonomous experiment. It consists of photoautotrophic and heterotrophic species cultures in separated compartments within a gas closed system. It should provide data on microbial revitalisation and growth kinetics in space environment, i.e. how these parameters are affected by radiation and gravity. Furthermore, the use of direct sun light, thermal control and radiation shielding allows to study new technological concepts.</div>

Chapter 6 - Biochemical Reaction Engineering

The conceptual design of a hybrid life support system based on the evaluation and comparison of terrestrial testbeds

<div class="htmlview paragraph">This paper describes an evolutionary method of technology integration for the development of a Lunar base life support system. The baseline is a partially-closed Regenerative Life Support System (RLSS) based upon Space Station Freedom physicochemical technology. The paper describes the stepwise evolution of this baseline system into a closed-loop, Lunar base Controlled Ecological Life Support System (LCELSS), a hybrid design which incorporates both physicochemical and bioregenerative technologies. The steps taken in the evolutionary process are derived from a rationale which addresses: 1) the incorporation of specific bioregenerative functions into the life support system, 2) the supplementation of specific physicochemical functions with bioregenerative systems, 3) the replacement of initial physicochemical technologies with more advanced technologies, and 4) the addition of new physicochemical technologies. The rationale for location of the stages in the evolutionary development sequence is based upon considerations of mass requirements for human life support, on crew nutritional requirements, and on functional characteristics of the life support technologies.</div>

The NASA Advanced Exploration Systems (AES) Life Support Systems (LSS) project strives to develop reliable, energy-efficient, and low-mass spacecraft systems to provide environmental control and life support systems (ECLSS) critical to enabling long duration human missions beyond low Earth orbit (LEO). Highly reliable, closed-loop life support systems are among the capabilities required for the longer duration human space exploration missions assessed by NASA's Habitability Architecture Team (HAT). The LSS project is focused on four areas: architecture and systems engineering for life support systems, environmental monitoring, air revitalization, and wastewater processing and water management. Starting with the international space station (ISS) LSS systems as a point of departure (where applicable), the mission of the LSS project is three-fold: 1. Address discrete LSS technology gaps 2. Improve the reliability of LSS systems 3. Advance LSS systems towards integrated testing on the ISS. This paper summarized the work being done in the four areas listed above to meet these objectives. Details will be given on the following focus areas: Systems Engineering and Architecture- With so many complex systems comprising life support in space, it is important to understand the overall system requirements to define life support system architectures for different space mission classes, ensure that all the components integrate well together and verify that testing is as representative of destination environments as possible. Environmental Monitoring- In an enclosed spacecraft that is constantly operating complex machinery for its own basic functionality as well as science experiments and technology demonstrations, it's possible for the environment to become compromised. While current environmental monitors aboard the ISS will alert crew members and mission control if there is an emergency, long-duration environmental monitoring cannot be done in-orbit as current methodologies rely largely on sending environmental samples back to Earth. The LSS project is developing onboard analysis capabilities that will replace the need to return air and water samples from space for ground analysis. Air Revitalization- The air revitalization task is comprised of work in carbon dioxide removal, oxygen generation and recovery and trace contamination and particulate control. The CO2 Removal and associated air drying development efforts under the LSS project are focused both on improving the current SOA technology on the ISS and assessing and examining the viability of other sorbents and technologies available in academia and industry. The Oxygen Generation and Recovery technology development area encompasses several sub-tasks in an effort to supply O2 to the crew at the required conditions, to recover O2 from metabolic CO2, and to recycle recovered O2 back to the cabin environment. Current state-of-the-art oxygen generation systems aboard space station are capable of generating or recovering approximately 40% of required oxygen; for exploration missions this percentage needs to be greatly increased. A spacecraft cabin trace contaminant and particulate control system serves to keep the environment below the spacecraft maximum allowable concentration (SMAC) for chemicals and particulates. Both passive (filters) and active (scrubbers) methods contribute to the overall TC & PC design. Work in the area of trace contamination and particulate control under the LSS project is focused on making improvements to the SOA TC & PC systems on ISS to improve performance and reduce consumables. Wastewater Processing and Water Management- A major goal of the LSS project is the development of water recovery systems to support long duration human exploration beyond LEO. Current space station wastewater processing and water management systems distill urine and wastewater to recover water from urine and humidity condensate in the spacecraft at a approximately 74% recovery rate. For longer, farther missions into deep space, that recovery rate must be greatly increased so that astronauts can journey for months without resupply cargo ships from Earth.

<div class="section abstract"><div class="htmlview paragraph">The inclusion of bioregenerative life support elements (i.e., plant growth systems and bioreactors) will significantly increase the total abundance of microorganisms in extraterrestrial facilities. If the microbial communities associated with these systems (e.g., biofilms attached to plant roots or hardware surfaces) serve as reservoirs for potentially pathogenic human-associated bacteria, then bioregenerative systems may represent a human health risk. Research at the Kennedy Space Center during the past several years has attempted to quantify this risk by assessing the capacity of different human-associated bacteria to survive in prototype ALS systems. Preliminary, short-term studies indicated that many potentially pathogenic human-associated bacterial species identified from past space missions (<i>Pseudomonas aerugi-nosa</i>, <i>Pseudomonas cepacia</i>, <i>Escherichia coli</i>, <i>Staphylococcus aureus</i>, and <i>Streptococcus pyogenes</i>) have the capacity to grow on the roots of plants, one of the largest potential sites of microbial activity in bioregen-erative life support systems. However, only <i>P. aeruginosa</i> could persist at detectable levels when competition from typical root-associated bacteria was present. Subsequent long-term plant growth experiments have confirmed the greater capacity of <i>P. aeruginosa</i> to persist in plant growth systems, although no human-associated bacteria tested to date have proliferated in the systems. Rather, relative success is measured by the rate at which bacterial numbers decrease following introduction. Recent and current studies have focused on the influence of community richness (i.e., the number of microbial species) on the ability of introduced human-associated bacteria to persist within prototype systems. Richness may be manipulated in a bioregenerative system; a stringent decontamination approach could lead to very low richness, but specific inoculation with either defined bacterial isolates or undefined mixtures of microbial communities would increase richness.</div></div>

A base on the Moon surface or a mission to Mars are potential destinations for human spaceflight, according to current space agencies’ plans. These scenarios pose several new challenges, since the environmental and operational conditions of the mission will strongly differ than those on the International Space Station (ISS). One critical parameter will be the increased mission duration and further distance from Earth, requiring a Life Support System (LSS) as independent as possible from Earth’s resources. Current LSS physico-chemical technologies at the ISS can recycle 90% of water and regain 42% of O2 from the astronaut’s exhaled CO2, but they are not able to produce food, which can currently only be achieved using biology. A future LSS will most likely include some of these technologies currently in use, but will also need to include biological components. A potential biological candidate are microalgae, which compared to higher plants, offer a higher harvest index, higher biomass productivity and require less water. Several algal species have already been investigated for space applications in the last decades, being Chlorella vulgaris a promising and widely researched species. C. vulgaris is a spherical single cell organism, with a mean diameter of 6 µm. It can grow in a wide range of pH and temperature levels and CO2 concentrations and it shows a high resistance to cross contamination and to mechanical shear stress, making it an ideal organism for long-term LSS. In order to continuously and efficiently produce the oxygen and food required for the LSS, the microalgae need to grow in a well-controlled and stable environment. Therefore, besides the biological aspects, the design of the cultivation system, the Photobioreactor (PBR), is also crucial. Even if research both on C. vulgaris and in general about PBRs has been carried out for decades, several challenges both in the biological and technological aspects need to be solved, before a PBR can be used as part of the LSS in a Moon base. Those include: radiation effects on algae, operation under partial gravity, selection of the required hardware for cultivation and food processing, system automation and long-term performance and stability.

SinterHab

Life Support and Habitation Systems (LSHS) is one of 10 Foundational Domains as part of the National Aeronautics and Space Administration s proposed Enabling Technology Development and Demonstration (ETDD) Program. LSHS will develop and mature technologies to sustain life on long duration human missions beyond Low Earth Orbit that are reliable, have minimal logistics supply and increase self-sufficiency. For long duration exploration missions, further closure of life support systems is paramount, including focus on key technologies for atmosphere revitalization, water recovery, waste management, thermal control and crew accommodation that recover additional consumable mass, reduce requirements for power, volume, heat rejection, crew involvement, and which have increased reliability and capability. Other areas of focus include technologies for radiation protection, environmental monitoring and fire protection. Beyond LEO, return to Earth will be constrained. The potability of recycled water and purity of regenerated air must be measured and certified aboard the spacecraft. Missions must be able to recover from fire events through early detection, use of non-toxic suppression agents, and operation of recovery systems that protect on-board Environmental Control and Life Support (ECLS) hardware. Without the protection of the Earth s geomagnetic field, missions beyond LEO must have improved radiation shielding and dosimetry, as well as warning systems to protect the crew against solar particle events. This paper will describe plans for the new LSHS Foundational Domain and mission factors that will shape its technology development portfolio.

BNCT is a new method in nuclear technology. The aim of BNCT application is to reduce human risk which used to kills cell targeting characteristic. The impact of using this technology should be considered before it is applied, among the effects of radiation on workers and the surrounding environment BNCT pilot plant. A research on modeling of BNCT pilot plant used a collimator for a 30 MeV cyclotron neutron sources which had been designed from the past research. Radiation shielding modeling for treatment room used MCNPX software. The radiation shielding was concrete baryte on each side that includes coated borated polyethylene 2 cm thick and it is featured with a sliding door with dimensions 220 × 87 × 200 cm coated with stainless steels 2 cm thick. Results obtained value equivalent dose rate of neutron and gamma of each 41.5 µSv.h<sup>-1</sup> and 2.05 µSv.h<sup>-1</sup>. Effects of radiation received by workers in the form of deterministic effects did not have a significant are impact.

Canadian advanced life support capacities and future directions

Techniques in Applied Microbiology

<div class="htmlview paragraph">MELISSA (Micro Ecological Life Support System Alternative) is a research project for the development of advanced life support systems, conducted by the European Space Agency. Its basic design is based on a loop of bioreactors with the main objective of the regeneration of the wastes generated by a crew into an edible material, with concomitant regeneration of the atmosphere for human respiration.</div> <div class="htmlview paragraph">The MELISSA Pilot Plant is a European facility to study and validate advanced life support systems. It has as main objectives the ground demonstration and characterization of a closed loop concept. This includes the development of the associated technology for its successful continuous operation such as water treatment, pathogen detection, food preparation, and other related items. At present time, the main research project developed in the Pilot plant is the MELISSA project.</div> <div class="htmlview paragraph">A key point in its development is the collection of experimental data under real operating conditions in order to perform mathematical modeling. This is a key issue in the approximation followed, both for the control and simulation of the individual bioreactors and the complete loop. The state of the art of the pilot plant is discussed, and particular emphasis is made in the description of the continuous operation of the interconnected bioreactors. Also the necessary associated research, required for its successful operation, such as the development of an advanced control system or the analysis of the effect of the malfunction of one compartment, on the subsequent ones are reviewed.</div>

As we make the transition from space visitor to space inhabitant, with an anticipated opening up of Earth orbit to space tourism, and in the lead up to a return to the Moon and a manned mission to Mars, the many unanswered questions surrounding sustaining human life in space prompts the question of how we plan for the success of these endeavors. Earth based simulations do not truly represent the intricate factors of isolation in space. BASE is proposed as a ‘workshop’ or ‘hangar’, devised to accumulate data in-situ in-orbit, in its mission to develop and test ideas for new orbital habitats (research and recreational configurations), and capsule ‘mock-up’ habitats for interplanetary travel. An on-board centrifuge would replicate the gravity fields of the Moon and Mars to give a crew prolonged exposure to conditions at destination arrival. The next question is how to achieve a large pressurized enclosure for this multi-purpose application? It seems reasonable that one of the next evolutionary steps in space architecture will utilize inflatable technology. The cylindrical modules of the ISS have reached natural limitations in size, flexibility and the quality of space utilized by the astronauts. NASA’s Transhab module provided a promising alternative in the form of an inflatable enclosure deployed about a central service core. The inflatable has to perform to design parameters imposed by the extreme environment of space, including pressurization, radiation shielding, micrometeorite shielding and thermal control. The resultant heavy multi-layered enclosure imposed limitations on the geometry and volume achievable. BASE asks the question; given the current technologies available, what are the possibilities when exploring a hybrid approach, combining inflatable and shell enclosures? In this way the primary function of the inflatable skin is pressurization, protected by ‘armadillo’ shell segments providing radiation & micrometeorite shielding, in addition to thermal control. BASE explores interior planning and comments on what configuration might lead to the best utilization of the space by astronauts. As we move towards sustaining a long term human presence in space, it is essential that new ways are found to interact and stimulate the senses within encapsulated spaces. BASE explores the concept of transforming the inside of the enclosure into a media skin providing sensory input. In assessing the quality of the interior living spaces, this paper investigates the link between a sensory rich environment and notions of ephemeral design. Since the space shuttle is scheduled for decommission within the next decade, BASE also looks towards alternative vehicles for delivery to orbit. The author has been involved in the development and realization of pod architecture across a number of projects. As a terrestrial spin-up, the author comments on the quality of these spaces as possible references for space habitats.

The MELISSA pilot plant facility as an integration test-bed for advanced life support systems