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Several small life sciences research modules were designed to accommodate both scientific research and K-12 educational objectives on the same spaceflight mission. The K-12 educational objectives are accomplished by participating students around the globe and complimented by ground experiments conducted in their own classrooms. The spaceflight research is analyzed by students through image analysis of downlinked video and still images. The science objectives of the mission often require sample return for more detailed sample analysis on ground. Integration of new modules as part of a CGBA Science Insert (CSI) into the CGBA incubator is facilitated through standardized interfaces. Engineering challenges, trades and system architecture designs are presented for the CGBA Incubator and the CSI life sciences habitats currently on board of ISS.

Environmentally sealed or isolated life sciences experiments such as plant growth chambers or animal habitats often require active temperature and humidity control. The interaction between the temperature and humidity control system, and performance limitations are shown based on experimental data using a small spaceflight plant growth chamber. Limited availability of electric power, and the chosen control system implementation constrain the obtainable temperature and humidity setpoint combinations.

Small spaceflight life science experiments, such as plant growth chambers and animal habitats, operate in unique environments. The experiments are often sealed systems that control atmospheric constituents, temperature, and humidity. Chemical scrubbers can be an efficient and reliable way to actively remove carbon dioxide for shorter experiment durations because they do not require power or complex technologies to operate. Several commercially available scrubbers were tested in both low and high humidity environments, and at low concentration levels of carbon dioxide similar to those found in plant chamber applications, to find a scrubber that was both effective and efficient for use in small life sciences experiments.

The present suite of advanced space plant cultivation facilities require a significant level of resources to launch and maintain in flight. The facilities are designed to accommodate a broad size range of plant species and are, therefore, not configured to support the specific growth requirements of small plant species such as Arabidopsis thaliana at maximum efficiency with respect to mass and power. The facilities are equally not configured to support automated plant harvesting or tissue processing procedures, but rely on crew intervention and time. The recent reorganization of both spaceflight opportunities and allocation of limited in-flight resources demand that experiments be conducted with optimal efficiency. The emergence of A. thaliana as a dominant space flight model organism utilized in research on vegetative and reproductive phase biology provides strong justification for the establishment of a dedicated cultivation system for this species.

Long distance/duration human space missions demand economical, regenerative life support systems. With naturally available light and low atmospheric pressures, missions to the surface of Mars might employ higher plants in a bioregenerative life support systems housed within a transparent inflatable greenhouse. The primary advantages of an inflatable structure are low mass, derived from pressure stabilization of the structure, the ability to collapse into a small storage volume for transit and ease of construction. Many high performance engineering polymer films exist today that are either highly or mostly transparent. Selection of one of these materials for an inflatable greenhouse to operate in the Mars surface environment poses a number of challenges. First, materials must be strong enough to resist the differential pressure loading between the inside plant environment and the near vacuum of thin Martian atmosphere.

Plant growth chambers, whether designed for Earth or space applications, should provide the basic means for supporting healthy plant growth of almost any species. These chambers typically satisfy species- and age-specific light, atmosphere composition, water and nutrient requirements. Engineering solutions to satisfy these basic requirements in different plant chambers may vary widely, and each species or each experimental protocol may need individual testing and adaptation of the supporting hardware and science protocols. This paper will summarize the design trades, tests and evaluation experiments conducted to ensure proper hardware functionality and proper hardware / lifeware compatibility for the desired experimental protocols in space.

BioServe Space Technologies has developed and flown a series of miniature habitats to house several different biological specimens and one biochemical experiment. This effort was in support of an educational program, Space Technology and Research Students (STARS), developed by SPACEHAB Inc. The STARS program gives students from around the world a chance to design and conduct their own spaceflight experiments. STARS-Bootes, the payload flown on STS-107, housed a Japanese Medaka fish experiment; a Chinese silkworm experiment; an American Harvester ant experiment; a Carpenter bee experiment from Liechtenstein, an Australian Orb Weaver spider experiment; and a biochemical crystal growth experiment from Israel. Each habitat was custom designed to suit each specimen's individual needs. The habitats provided passive humidity control, lighting, feeding areas, and containment as well as an artificial environment for the specimens to be observed in.

PGBA, a 0.08m2 / 27 liter spaceflight plant chamber payload employs two temperature-controlled liquid coolant loops to control the temperature and humidity of the sealed plant chamber independently. Cabin-air cooled thermoelectric heat pumps control the temperature of the water-alcohol coolant fluid in each loop, which is circulated by small, low-power, magnetically-coupled positive displacement gear pumps, designed to meet NASA safety requirements. Pulse-width-modulated DC current control circuits, controlled by two PI software controllers, maintain temperature and humidity accurately. The coolant loops feature bellows-based expansion vessels to accommodate thermal expansion and pressure fluctuations. Pressure sensors monitor the proper function and performance of the system. Pressure decay tests and unique fill procedures should ensure leak and air bubble-free operation.

Porous plate dehumidifiers (PPD) and porous tube nutrient delivery systems (PTNDS) are designed to provide a means for accurate environmental control, and also allow for two-phase flow separation in microgravity through surface tension. The technological challenges associated with these systems arise from the requirement to accurately measure and control the very small pressures that typically occur within and across the porous media. On-orbit automated priming or filling of the system in the absence of gravity may be necessary. Several porous plate dehumidifiers and porous tube nutrient delivery systems have been tested and evaluated, and experimental results for engineering design are presented.

BioServe Space Technologies is developing a set of habitats which will support various biological specimens and one biochemical experiment. The habitats are being developed to support a spaceflight educational payload called Space Technology and Research Students (STARS). The STARS program entrusts high school students with the development and design of their own spaceflight experiments. Experiments are solicited from various countries and primarily focus on the life sciences. Once selected, all experiments must be accommodated within one middeck locker sized payload, the Commercial Generic Bioprocessing Apparatus.

The increased demand in the area of space life sciences necessitates the need for more experimentation hardware with increased capabilities. Due to the high cost of hardware development for space based research, new hardware should be modular in design and suited to handle a variety of different experiments. The fluid handling systems found in experimentation hardware will often share many of the same requirements for different experiments. A design process that can be used for biological fluid handling systems that cover a wide range of experimentation requirements is proposed. Important parameters to be considered when making a trade study for selection of system components will be discussed. This paper will address topics of current research in space life sciences and describe state of the art hardware that is available or under development for use.

During the past three decades, both the Russian and American space programs have demonstrated that human presence in space can be sustained for either short or long durations as long as essential life support expendables are regularly resupplied from Earth. In the last decade, increasing attention has been placed on the development of bioregenerative life support systems which minimize resupply requirements in order to sustain long-duration human exploration of the Moon or Mars and eventually human settlement beyond Earth. Bio-regenerative life support systems, however, remain among the most challenging of all the critical elements required for long duration human space missions. In the near term, the in-space cultivation of salad-type vegetables for crew consumption has been proposed as critical first step towards using bioregenerative technologies to effectively reduce the total reliance by crewmembers on the resupply of food.

Accurate root zone moisture control in microgravity plant growth systems is problematic. With gravity, excess water drains along a vertical gradient, and water recovery is easily accomplished. In microgravity, the distribution of water is less predictable and can easily lead to flooding, as well as anoxia. Microgravity water delivery systems range from solidified agar, water-saturated foams, soils and hydroponics soil surrogates including matrix-free porous tube delivery systems. Surface tension and wetting along the root substrate provides the means for adequate and uniform water distribution. Reliable active soil moisture sensors for an automated microgravity water delivery system currently do not exist. Surrogate parameters such as water delivery pressure have been less successful.

Engineers and scientists from BioServe Space Technologies and Kennedy Space Center (KSC) are developing a flight-rated payload for the evaluation of two space-based plant nutrient delivery systems (NDS's). The hardware is comprised of BioServe's Plant Generic Bioprocessing Apparatus (PGBA) and KSC's Porous Tube Insert Module (PTIM). The PGBA, a double-middeck locker, will serve as the host carrier for the PTIM and will provide computer control of temperature, relative humidity, and carbon dioxide levels. The PTIM will insert into the PGBA's growth chamber and will facilitate the side-by-side comparison of the two NDS's: 1) the porous tube NDS, consisting of six porous tubes with seeds mounted in close proximity to the tubes, and 2) a substrate-based NDS, with three compartments each containing a porous tube embedded in a particulate substrate.

Improvements in plant illumination, irrigation, and thermal control systems have led to significant progress in the cultivation capability of space flight plant growth facilities. An area that has received little attention, however, is the on-orbit ability to sow and initiate the germination of seed within these facilities. In addition to the need for adequate levels of water and gas exchange, seeds must be maintained in a specific physical orientation due to the absence of a gravity vector to ensure that emerging root and shoot material is directed in an appropriate orientation. An approach involving the immobilization of seed in a matrix material is being evaluated as a means of not only providing appropriate germination conditions but also the efficient physical manipulation of seed. The design of a mechanized sowing system, based on the manipulation of matrix immobilized seed is presented in this paper.

Spaceflight plant growth chambers require an atmosphere control system to maintain adequate levels of carbon dioxide and oxygen, as well as to limit trace gas components, for optimum or reproducible scientific performance. Recent atmosphere control anomalies of a spaceflight plant chamber, resulting in unstable CO2 control, have been analyzed. An activated carbon filter, designed to absorb trace gas contaminants, has proven detrimental to the atmosphere control system due to its large buffer capacity for CO2. The latest plant chamber redesign addresses the control anomalies and introduces a new approach to atmosphere control (low leakage rate chamber, regenerative control of CO2, O2, and ethylene).

A microgravity dehumidification system for plant growth experiments requires the generation of no free-liquid condensate and the recovery of water for reuse. In membrane dehumidification, the membrane is a barrier between the humid air phase and a liquid coolant water. The coolant water temperature combined with a trans-membrane pressure differential establishes a water flux from the humid air into the coolant water. Building on the work of others, we directly compared hydrophilic and hydrophobic membranes for humidity control. Hydrophobic membranes did not meet the required operational parameters. In a direct comparison of the hydrophilic membranes, cellulose ester membranes were superior to metal and ceramic membranes in the categories of condensation flux per surface area, ease of start-up and stability. However, cellulose ester membranes were inferior to metal membranes in one significant category, longevity/durability.