A high-performance ground-based prototype of horn-type sequential vegetable production facility for life support system in space

Vegetable cultivation plays a crucial role in dietary supplements and psychosocial benefits of the crew during manned space flight. Here we developed a ground-based prototype of horn-type sequential vegetable production facility, named Horn-type Producer (HTP), which was capable of simulating the microgravity effect and the continuous cultivation of leaf–vegetables on root modules. The growth chamber of the facility had a volume of 0.12 m³, characterized by a three-stage space expansion with plant growth. The planting surface of 0.154 m² was comprised of six ring-shaped root modules with a fibrous ion-exchange resin substrate. Root modules were fastened to a central porous tube supplying water, and moved forward with plant growth. The total illuminated crop area of 0.567 m² was provided by a combination of red and white light emitting diodes on the internal surfaces. In tests with a 24-h photoperiod, the productivity of the HTP at 0.3 kW for lettuce achieved 254.3 g eatable biomass per week. Long-term operation of the HTP did not alter vegetable nutrition composition to any great extent. Furthermore, the efficiency of the HTP, based on the Q-criterion, was 7 × 10⁻⁴ g² m⁻³ J⁻¹. These results show that the HTP exhibited high productivity, stable quality, and good efficiency in the process of planting lettuce, indicative of an interesting design for space vegetable production.     

Development of a CELSS Experimental Facility

A CELSS Experimental Facility was developed two years ago. It contains a volume of about 40.0 m³ and a cultivating area of about 8.4 m²; its interior atmospheric parameters such as temperature, relative humidity, oxygen concentration, carbon dioxide concentration, total pressure, lighting intensity, photoperiod, water content in the growing-matrix, CO₂-added accumulative amount, O₂-released accumulative amount and ethylene concentration are all controlled and logged automatically and effectively; its growing system consists of two rows of racks along its left-and-right sides separately, each side holds two upper-and-lower layers, and the vertical distance of each growing bed can be adjusted automatically and independently; lighting sources consist of both red (95%) and blue (5%) light-emitting diodes (LED), and the average lighting intensity of each lamp bank at 20-cm distance position under it, reaches to 255.0 μmol m⁻² s⁻¹. After that, demonstrating tests were carried out and were finally followed by growing lettuce in the facility. The results showed that all subsystems operated well and all parameters were controlled automatically and efficiently. The lettuce plants in the system could grow much well. Successful development of this system laid a necessary foundation for future larger-scale studies on CELSS integration technique.     

Second generation prototype design and testing for a high altitude Venus balloon

This paper describes the development of a second generation prototype balloon intended for flight in the upper atmosphere of Venus. The design of this new prototype incorporates lessons learned from the construction and testing of the first generation prototype, including finite element analyses of the balloon stresses and deformations, measured leak performance after handling and packaging, permeability and optical property measurements on material samples, and sulfuric acid testing. An improved design for the second generation prototype was formulated based on these results, although the spherical shape and 5.5 m diameter size were retained. The resulting balloon has a volume of 87 m³ and is capable of carrying a 45 kg payload at a 55 km altitude at Venus. The design and fabrication of the new prototype is described, along with test data for inflation and leakage performance.     

Modelling the effects of microgravity on the permeability of air interface respiratory epithelial cell layers

Although it has been suggested that microgravity might affect drug absorption in vivo, drug permeability across epithelial barriers has not yet been investigated in vitro during modelled microgravity. Therefore, a cell culture/diffusion chamber was designed specifically to accommodate epithelial cell layers in a 3D-clinostat and allow epithelial permeability to be measured under microgravity conditions in vitro with minimum alteration to established cell culture techniques. Human respiratory epithelial Calu-3 cell layers were used to model the airway epithelium. Cells grown at an air interface in the diffusion chamber from day 1 or day 5 after seeding on 24-well polyester Transwell cell culture inserts developed a similar transepithelial electrical resistance (TER) to cells cultured in conventional cell culture plates. Confluent Calu-3 layers exposed to modelled microgravity in the 3D-clinostat for up to 48 h maintained their high TER. The permeability of the paracellular marker ¹⁴C-mannitol was unaffected after a 24 h rotation of the cell layers in the 3D-clinostat, but was increased 2-fold after 48 h of modelled microgravity. It was demonstrated that the culture/diffusion chamber developed is suitable for culturing epithelial cell layers and, when subjected to rotation in the 3D-clinostat, will be a valuable in vitro system in which to study the influence of microgravity on epithelial permeability and drug transport.     

Effects of lighting and air movement on temperatures in reproductive organs of plants in a closed plant growth facility

Temperature increases in plant reproductive organs such as anthers and stigmas could cause fertility impediments and thus produce sterile seeds under artificial lighting conditions without adequately controlled environments in closed plant growth facilities. There is a possibility such a situation could occur in Bioregenerative Life Support Systems under microgravity conditions in space because there will be little natural convective or thermal mixing. This study was conducted to determine the temperature of the plant reproductive organs as affected by illumination and air movement under normal gravitational forces on the earth and to make an estimation of the temperature increase in reproductive organs in closed plant growth facilities under microgravity in space. Thermal images of reproductive organs of rice and strawberry were captured using infrared thermography at air temperatures of 10–11 °C. Compared to the air temperature, temperatures of petals, stigmas and anthers of strawberry increased by 24, 22 and 14 °C, respectively, after 5 min of lighting at an irradiance of 160 W m⁻² from incandescent lamps. Temperatures of reproductive organs and leaves of strawberry were significantly higher than those of rice. The temperatures of petals, stigmas, anthers and leaves of strawberry decreased by 13, 12, 13 and 14 °C, respectively, when the air velocity was increased from 0.1 to 1.0 ms⁻¹. These results show that air movement is necessary to reduce the temperatures of plant reproductive organs in plant growth facilities.     

Development of a plant growth unit for growing plants over a long-term life cycle under microgravity conditions.

To study the effect of the space environment on plant growth including the reproductive growth and genetic aberration for a long-term plant life cycle, we have initiated development of a new type of facility for growing plants under microgravity conditions. The facility is constructed with subsystems for controlling environmental elements. In this paper, the concept of the facility design is outlined. Subsystems controlling air temperature, humidity, CO2 concentration, light and air circulation around plants and delivering recycled water and nutrients to roots are the major concerns. Plant experiments for developing the facility and future plant experiments with the completed facility are also overviewed. We intend to install this facility in the Japan Experiment Facility (JEM) boarded on the International Space Station.     

Vegetable production facility as a part of a closed life support system in a Russian Martian space flight scenario

A Manned Mars Mission scenario had been developed in frame of the Project 1172 supported International Science & Technology Center in Moscow. The Mars transit vehicle (MTV) supposed to have a crew of 4–6 with Pilot Laboratory compartment volume of 185 m³ and with inner diameter of 4.1 m. A vegetable production facility with power consumption up to 10 kW is being considered as a component of the life support system to supply crew members by fresh vegetables during the mission. Proposed design of conveyor-type plant growth facility (PGF) comprised of 4-modules. Each module has a cylindrical planting surface and spiral cylindrical LED assembly to provide a high specific productivity relative to utilized onboard resources. Each module has a growth chamber that will be from 0.7 m to 1.5 m in length, and a crop illuminated area from 1.7 m² to 4.0 m². Leafy crops (cabbage, lettuce, spinach, chard, etc.) have been selected for module 1, primarily because of the highest specific productivity per consumed resources. Dietitians have recommended also carrot crop for module 2, pepper for module 3 and tomato for module 4. The maximal total PGF light energy estimated as 1.16 kW and total power consumption as about 7 kW. The module 1 characteristics have been calculated using own experimental data, information from the best on ground plant growth experiments with artificial light were used to predict crop productivity and biomass composition in the another modules. 4-module PGF could produce nearly 0.32 kg per crew member per day of fresh edible biomass, which would be about 50% of recommended daily vegetable supplement. An average crop harvest index is estimated as 0.75. The MTV food system could be entirely closed in terms of vitamins C and A with help of the PGF. In addition the system could provide 10–25% of essential minerals and vitamins of group B, and about 20% of food fibers. The present state of plant growth technology allows formulating of requirements specification for the flight-qualified modules.     

Development of a ground-based space micro-algae photo-bioreactor

The purpose of the research is to develop a photo-bioreactor which may produce algae protein and oxygen for future astronauts in comparatively long-term exploration, and remove carbon dioxide in a controlled ecological life support system. Based on technical parameters and performance requirements, the project planning, design drafting, and manufacture were conducted. Finally, a demonstration test for producing algae was done. Its productivity for micro-algae and performance of the photo-bioreactor were evaluated. The facility has nine subsystems, including the reactor, the illuminating unit, the carbon dioxide (CO₂) production unit and oxygen (O₂) generation unit, etc. The demonstration results showed that the facility worked well, and the parameters, such as energy consumption, volume, and productivity for algae, met with the design requirement. The density of algae in the photo-bioreactor increased from 0.174 g (dry weight) L⁻¹ to 4.064 g (dry weight) L⁻¹ after 7 days growth. The principle of providing CO₂ in the photo-bioreactor for algae and removing O₂ from the culture medium was suitable for the demand of space conditions. The facility has reasonable technical indices, and smooth and dependable performances.     

Developing strategies for automated remote plant production systems: Environmental control and monitoring of the Arthur Clarke Mars Greenhouse in the Canadian High Arctic

The Arthur Clarke Mars Greenhouse is a unique research facility dedicated to the study of greenhouse engineering and autonomous functionality under extreme operational conditions, in preparation for extraterrestrial biologically-based life support systems. The Arthur Clarke Mars Greenhouse is located at the Haughton Mars Project Research Station on Devon Island in the Canadian High Arctic. The greenhouse has been operational since 2002. Over recent years the greenhouse has served as a controlled environment facility for conducting scientific and operationally relevant plant growth investigations in an extreme environment. Since 2005 the greenhouse has seen the deployment of a refined nutrient control system, an improved imaging system capable of remote assessment of basic plant health parameters, more robust communication and power systems as well as the implementation of a distributed data acquisition system. Though several other Arctic greenhouses exist, the Arthur Clarke Mars Greenhouse is distinct in that the focus is on autonomous operation as opposed to strictly plant production. Remote control and autonomous operational experience has applications both terrestrially in production greenhouses and extraterrestrially where future long duration Moon/Mars missions will utilize biological life support systems to close the air, food and water loops. Minimizing crew time is an important goal for any space-based system. The experience gained through the remote operation of the Arthur Clarke Mars Greenhouse is providing the experience necessary to optimize future plant production systems and minimize crew time requirements. Internal greenhouse environmental data shows that the fall growth season (July–September) provides an average photosynthetic photon flux of 161.09 μmol m⁻² s⁻¹ (August) and 76.76 μmol m⁻² s⁻¹ (September) with approximately a 24 h photoperiod. The spring growth season provides an average of 327.51 μmol m⁻² s⁻¹ (May) and 339.32 μmol m⁻² s⁻¹ (June) demonstrating that even at high latitudes adequate light is available for crop growth during 4–5 months of the year. The Canadian Space Agency Development Greenhouse [now operational] serves as a test-bed for evaluating new systems prior to deployment in the Arthur Clarke Mars Greenhouse. This greenhouse is also used as a venue for public outreach relating to biological life support research and its corresponding terrestrial spin-offs.     

Cowpeas and pinto beans: Performance and yields of candidate space crops in the laboratory biosphere closed ecological system

An experiment utilizing cowpeas (Vigna unguiculata L.), pinto beans (Phaseolus vulgaris L.) and Apogee ultra-dwarf wheat (Triticum sativa L.) was conducted in the soil-based closed ecological facility, Laboratory Biosphere, from February to May 2005. The lighting regime was 13 h light/11 h dark at a light intensity of 960 μmol m⁻² s⁻¹, 45 mol m⁻² day⁻¹ supplied by high-pressure sodium lamps. The pinto beans and cowpeas were grown at two different planting densities. Pinto bean production was 341.5 g dry seed m⁻² (5.42 g m⁻² day⁻¹) and 579.5 dry seed m⁻² (9.20 g m⁻² day⁻¹) at planted densities of 32.5 plants m⁻² and 37.5 plants m⁻², respectively. Cowpea yielded 187.9 g dry seed m⁻² (2.21 g m⁻² day⁻¹) and 348.8 dry seed m⁻² (4.10 g m⁻² day⁻¹) at planted densities of 20.8 plants m⁻² and 27.7 plants m⁻², respectively. The crop was grown at elevated atmospheric carbon dioxide levels, with levels ranging from 300–3000 ppm daily during the majority of the crop cycle. During early stages (first 10 days) of the crop, CO₂ was allowed to rise to 7860 ppm while soil respiration dominated, and then was brought down by plant photosynthesis. CO₂ was injected 27 times during days 29–71 to replenish CO₂ used by the crop during photosynthesis. Temperature regime was 24–28 °C day/deg 20–24 °C night. Pinto bean matured and was harvested 20 days earlier than is typical for this variety, while the cowpea, which had trouble establishing, took 25 days more for harvest than typical for this variety. Productivity and atmospheric dynamic results of these studies contribute toward the design of an envisioned ground-based test bed prototype Mars base.     

Seed-to-seed growth of Arabidopsis thaliana on the International Space Station.

The assembly of the International Space Station (ISS) as a permanent experimental outpost has provided the opportunity for quality plant research in space. To take advantage of this orbital laboratory, engineers and scientists at the Wisconsin Center for Space Automation and Robotics (WCSAR), University of Wisconsin-Madison, developed a plant growth facility capable of supporting plant growth in the microgravity environment. Utilizing this Advanced Astroculture (ADVASC) plant growth facility, an experiment was conducted with the objective to grow Arabidopsis thaliana plants from seed-to-seed on the ISS. Dry Arabidopsis seeds were anchored in the root tray of the ADVASC growth chamber. These seeds were successfully germinated from May 10 until the end of June 2001. Arabidopsis plants grew and completed a full life cycle in microgravity. This experiment demonstrated that ADVASC is capable of providing environment conditions suitable for plant growth and development in microgravity. The normal progression through the life cycle, as well as the postflight morphometric analyses, demonstrate that Arabidopsis thaliana does not require the presence of gravity for growth and development.     

Prototype design and testing of a Venus long duration,high altitude balloon

This paper describes the design, fabrication and testing of a full scale prototype balloon intended for long duration flight in the upper atmosphere of Venus. The balloon is 5.5 m in diameter and is designed to carry a 45 kg payload at an altitude of 55 km. The balloon material is a 180 g/m² multi-component laminate comprised of the following layers bonded together from outside to inside: aluminized Teflon film, aluminized Mylar film, Vectran fabric and a polyurethane coating. This construction provides the required balloon functional characteristics of low gas permeability, sulfuric acid resistance and high strength for superpressure operation. The design burst superpressure is 39,200 Pa which is predicted to be 3.3 times the worst case value expected during flight at the highest solar irradiance in the mission profile. The prototype is constructed from 16 gores with bi-taped seams employing a sulfuric acid resistant adhesive on the outside. Material coupon tests were performed to evaluate the optical and mechanical characteristics of the laminate. These were followed by full prototype tests for inflation, leakage and sulfuric acid tolerance. The results confirmed the suitability of this balloon design for use at Venus in a long duration mission. The various data are presented and the implications for mission design and operation are discussed.     

Evaluation of upper body muscle activity during cardiopulmonary resuscitation performance in simulated microgravity

Performance of efficient single-person cardiopulmonary resuscitation (CPR) is vital to maintain cardiac and cerebral perfusion during the 2–4 min it takes for deployment of advanced life support during a space mission. The aim of the present study was to investigate potential differences in upper body muscle activity during CPR performance at terrestrial gravity (+1Gz) and in simulated microgravity (μG). Muscle activity of the triceps brachii, erector spinae, rectus abdominis and pectoralis major was measured via superficial electromyography in 20 healthy male volunteers. Four sets of 30 external chest compressions (ECCs) were performed on a mannequin. Microgravity was simulated using a body suspension device and harness; the Evetts–Russomano (ER) method was adopted for CPR performance in simulated microgravity. Heart rate and perceived exertion via Borg scores were also measured. While a significantly lower depth of ECCs was observed in simulated microgravity, compared with +1Gz, it was still within the target range of 40–50 mm. There was a 7.7% decrease of the mean (±SEM) ECC depth from 48 ± 0.3 mm at +1Gz, to 44.3 ± 0.5 mm during microgravity simulation (p < 0.001). No significant difference in number or rate of compressions was found between the two conditions. Heart rate displayed a significantly larger increase during CPR in simulated microgravity than at +1Gz, the former presenting a mean (±SEM) of 23.6 ± 2.91 bpm and the latter, 76.6 ± 3.8 bpm (p < 0.001). Borg scores were 70% higher post-microgravity compressions (17 ± 1) than post +1Gz compressions (10 ± 1) (p < 0.001). Intermuscular comparisons showed the triceps brachii to have significantly lower muscle activity than each of the other three tested muscles, in both +1Gz and microgravity. As shown by greater Borg scores and heart rate increases, CPR performance in simulated microgravity is more fatiguing than at +1Gz. Nevertheless, no significant difference in muscle activity between conditions was found, a result that is favourable for astronauts, given the inevitable muscular and cardiovascular deconditioning that occurs during space travel.     

Crop productivities and radiation use efficiencies for bioregenerative life support

NASA’s Biomass Production Chamber (BPC) at Kennedy Space Center was decommissioned in 1998, but several crop tests were conducted that have not been reported in the open literature. These include several monoculture studies with wheat, soybean, potato, lettuce, and tomato. For all of these studies, either 10 or 20 m² of plants were grown in an atmospherically closed chamber (113 m³ vol.) using a hydroponic nutrient film technique along with elevated CO₂ (1000 or 1200 μmol mol⁻¹). Canopy light (PAR) levels ranged from 17 to 85 mol m⁻² d⁻¹ depending on the species and photoperiod. Total biomass (DM) productivities reached 39.6 g m⁻² d⁻¹ for wheat, 27.2 g m⁻² d⁻¹ for potato, 19.6 g m⁻² d⁻¹ for tomato, 15.7 g m⁻² d⁻¹ for soybean, and 7.7 g m⁻² d⁻¹ for lettuce. Edible biomass (DM) productivities reached 18.4 g m⁻² d⁻¹ for potato, 11.3 g m⁻² d⁻¹ for wheat, 9.8 g m⁻² d⁻¹ for tomato, 7.1 g m⁻² d⁻¹ for lettuce, and 6.0 g m⁻² d⁻¹ for soybean. The corresponding radiation (light) use efficiencies for total biomass were 0.64 g mol⁻¹ PAR for potato, 0.59 g DM mol⁻¹ for wheat, 0.51 g mol⁻¹ for tomato, 0.46 g mol⁻¹ for lettuce, and 0.43 g mol⁻¹ for soybean. Radiation use efficiencies for edible biomass were 0.44 g mol⁻¹ for potato, 0.42 g mol⁻¹ for lettuce, 0.25 g mol⁻¹ for tomato, 0.17 g DM mol⁻¹ for wheat, and 0.16 g mol⁻¹ for soybean. By initially growing seedlings at a dense spacing and then transplanting them to the final production area could have saved about 12 d in each production cycle, and hence improved edible biomass productivities and radiation use efficiencies by 66% for lettuce (to 11.8 g m⁻² d⁻¹ and 0.70 g mol⁻¹), 16% for tomato (to 11.4 g m⁻² d⁻¹and 0.29 g mol⁻¹), 13% for soybean (to 6.9 g m⁻² d⁻¹ and 0.19 g mol⁻¹), and 13% for potato (to 20.8 g m⁻² d⁻¹ and 0.50 g mol⁻¹). Since wheat was grown at higher densities, transplanting seedlings would not have improved yields. Tests with wheat resulted in a relatively low harvest index of 29%, which may have been caused by ethylene or other organic volatile compounds (VOCs) accumulating in the chamber. Assuming a higher harvest index of 40% could be achieved by scrubbing VOCs, productivity of wheat seed could have been improved nearly 40% to 15.8 g m⁻² d⁻¹ and edible biomass radiation use efficiency to 0.30 g mol⁻¹.     

空间站微重力流体实验设备需求分析

对国际空间站和中国科学实验卫星及载人飞行器上开展的微重力流体实验情况进行论述和分析,重点分析了国际空间站（ISS）微重力流体科学实验设备情况.根据中国空间微重力流体物理科学发展需求,结合国际空间站微重力流体科学实验对设备的需求,提出了未来在中国空间站开展微重力流体实验时空间实验设备需要重点考虑和解决的问题,同时提出相关设计建议.      

Simulated microgravity inhibits the proliferation of K562 erythroleukemia cells but does not result in apoptosis

Astronauts and experimental animals in space develop the anemia of space flight, but the underlying mechanisms are still unclear. In this study, the impact of simulated microgravity on proliferation, cell death, cell cycle progress and cytoskeleton of erythroid progenitor-like K562 leukemia cells was observed. K562 cells were cultured in NASA Rotary Cell Culture System (RCCS) that was used to simulate microgravity (at 15 rpm). After culture for 24 h, 48 h, 72 h, and 96 h, the cell densities cultured in RCCS were only 55.5%, 54.3%, 67.2% and 66.4% of the flask-cultured control cells, respectively. The percentages of trypan blue-stained dead cells and the percentages of apoptotic cells demonstrated no difference between RCCS-cultured cells and flask-cultured cells at every time points (from 12 h to 96 h). Compared with flask-cultured cells, RCCS culture induced an accumulation of cell number at S phase concomitant with a decrease at G0/G1 and G2/M phases at 12 h. But 12 h later (from 24 h to 60 h), the distribution of cell cycle phases in RCCS-cultured cells became no difference compared to flask-cultured cells. Consistent with the changes of cell cycle distribution, the levels of intercellular cyclins in RCCS-cultured cells changed at 12 h, including a decrease in cyclin A, and the increasing in cyclin B, D1 and E, and then (from 24 h to 36 h) began to restore to control levels. After RCCS culture for 12–36 h, the microfilaments showed uneven and clustered distribution, and the microtubules were highly disorganized. These results indicated that RCCS-simulated microgravity could induce a transient inhibition of proliferation, but not result in apoptosis, which could involve in the development of space flight anemia. K562 cells could be a useful model to research the effects of microgravity on differentiation and proliferation of hematopoietic cells.     

The water cycle in closed ecological systems: Perspectives from the Biosphere 2 and Laboratory Biosphere systems

To achieve sustainable, healthy closed ecological systems requires solutions to challenges of closing the water cycle – recycling wastewater/irrigation water/soil medium leachate and evaporated water and supplying water of required quality as needed for different needs within the facility. Engineering Biosphere 2, the first multi-biome closed ecological system within a total airtight footprint of 12,700 m² with a combined volume of 200,000 m³ with a total water capacity of some 6 × 10⁶ L of water was especially challenging because it included human inhabitants, their agricultural and technical systems, as well as five analogue ecosystems ranging from rainforest to desert, freshwater ecologies to saltwater systems like mangrove and mini-ocean coral reef ecosystems. By contrast, the Laboratory Biosphere – a small (40 m³ volume) soil-based plant growth facility with a footprint of 15 m² – is a very simplified system, but with similar challenges re salinity management and provision of water quality suitable for plant growth. In Biosphere 2, water needs included supplying potable water for people and domestic animals, irrigation water for a wide variety of food crops, and recycling and recovering soil nutrients from wastewater. In the wilderness biomes, providing adequately low salinity freshwater terrestrial ecosystems and maintaining appropriate salinity and pH in aquatic/marine ecosystems were challenges. The largest reservoirs in Biosphere 2 were the ocean/marsh with some 4 × 10⁶ L, soil with 1 to 2 × 10⁶ l, primary storage tank with 0 to 8 × 10⁵ L and storage tanks for condensate and soil leachate collection and mixing tanks with a capacity of 1.6 × 10⁵ L to supply irrigation for farm and wilderness ecosystems. Other reservoirs were far smaller – humidity in the atmosphere (2 × 10³ L), streams in the rainforest and savannah, and seasonal pools in the desert were orders of magnitude smaller (8 × 10⁴ L). Key technologies included condensation from humidity in the air handlers and from the glass space frame to produce high quality freshwater, wastewater treatment with constructed wetlands and desalination through reverse osmosis and flash evaporation were key to recycling water with appropriate quality throughout the Biosphere 2 facility. Wastewater from all human uses and the domestic animals in Biosphere 2 was treated and recycled through a series of constructed wetlands, which had hydraulic loading of 0.9–1.1 m³ day⁻¹ (240–290 gal d⁻¹). Plant production in the wetland treatment system produced 1210 kg dry weight of emergent and floating aquatic plant wetland which was used as fodder for the domestic animals while remaining nutrients/water was reused as part of the agricultural irrigation supply. There were pools of water with recycling times of days to weeks and others with far longer cycling times within Biosphere 2. By contrast, the Laboratory Biosphere with a total water reservoir of less than 500 L has far quicker cycling rapidity: for example, atmospheric residence time for water vapor was 5–20 min in the Laboratory Biosphere vs. 1–4 h in Biosphere 2, as compared with 9 days in the Earth’s biosphere. Just as in Biosphere 2, humidity in the Laboratory Biosphere amounts to a very small reservoir of water. The amount of water passing through the air in the course of a 12-h operational day is two orders of magnitude greater than the amount stored in the air. Thus, evaporation and condensation collection are vital parts of the recycle system just as in Biosphere 2. The water cycle and sustainable water recycling in closed ecological systems presents problems requiring further research – such as how to control buildup of salinity in materially closed ecosystems and effective ways to retain nutrients in optimal quantity and useable form for plant growth. These issues are common to all closed ecological systems of whatever size, including planet Earth’s biosphere and are relevant to a global environment facing increasing water shortages while maintaining water quality for human and ecosystem health. Modular biospheres offer a test bed where technical methods of resolving these problems can be tested for feasibility.     

Gas exchange rates of potato stands for bioregenerative life support

Plants can provide a means for removing carbon dioxide (CO₂) while generating oxygen (O₂) and clean water for life support systems in space. To study this, 20 m² stands of potato (Solanum tuberosum L.) plants were grown in a large (113 m³ vol.), atmospherically closed chamber. Photosynthetic uptake of CO₂ by the stands was detected about 10 DAP (days after planting), after which photosynthetic rates rose rapidly as stand ground cover and total light interception increased. Photosynthetic rates peaked ca. 50 DAP near 45 μmol CO₂ m⁻² s⁻¹ under 865 μmol m⁻² s⁻¹ PPF (average photosynthetic photon flux), and near 35 μmol CO₂ m⁻² s⁻¹ under 655 μmol m⁻² s⁻¹ PPF. Short term changes in PPF caused a linear response in stand photosynthetic rates up to 1100 μmol m⁻² s⁻¹ PPF, with a light compensation point of 185 μmol m⁻² s⁻¹ PPF. Comparisons of stand photosynthetic rates at different CO₂ concentrations showed a classic C₃ response, with saturation occurring near 1200 μmol mol⁻¹ CO₂ and compensation near 100 μmol mol⁻¹ CO₂. In one study, the photoperiod was changed from 12 h light/12 h dark to continuous light at 58 DAP. This caused a decrease in net photosynthetic rates within 48 h and eventual damage (scorching) of upper canopy leaves, suggesting the abrupt change stressed the plants and/or caused feedback effects on photosynthesis. Dark period (night) respiration rates increased during early growth as standing biomass increased and peaked near 9 μmol CO₂ m⁻² s⁻¹ ca. 50 DAP, after which rates declined gradually with age. Stand transpiration showed a rapid rise with canopy ground cover and peaked ca. 50 DAP near 8.9 L m⁻² d⁻¹ under 860 μmol m⁻² s⁻¹ PPF and near 6.3 L m⁻² d⁻¹ under 650 μmol m⁻² s⁻¹ PPF. Based on the best photosynthetic rates from these studies, approximately 25 m² of potato plants under continuous cultivation would be required to support the CO₂ removal and O₂ requirements for one person.     

空间毛细管式蛋白质结晶室样品加载技术研究

采用X-elax射线衍射技术研究蛋白质分子结构与功能的必要前提是获得高质量的蛋白质晶体.空间微重力环境是生长优质蛋白质晶体的理想场所.蛋白质样品的加载工艺对于空间蛋白质结晶实验的成效具有重要影响.针对为神舟八号飞船空间实验新研制的毛细管式空间蛋白质结晶室,结合样品加载基本流程,对加载工艺和伴随的气泡缺陷问题进行了系统和深入分析,确定了针头形状、毛细管封口质量和硅化效果、样品加载工具以及毛细管夹持方式等影响因素,并获得了实验测试验证.在此基础上,通过改进毛细管烧制工艺和样品加载工具,研制和使用专用毛细管夹具等措施,简化了蛋白质样品加载工艺,消除了气泡缺陷,提高了加载效率.新工艺的实施保证了空间实验任务的顺利完成.      

Comparison of hindlimb unloading and partial weight suspension models for spaceflight-type condition induced effects on white blood cells

Animal models are frequently used to assist in the determination of the long- and short-term effects of space flight. The space environment, including microgravity, can impact many physiological and immunological system parameters. It has been found that ground based models of microgravity produce changes in white blood cell counts, which negatively affects immunologic function. As part of the Center of Acute Radiation Research (CARR), we compared the acute effects on white blood cell parameters induced by the more traditionally used animal model of hindlimb unloading (HU) with a recently developed reduced weightbearing analog known as partial weight suspension (PWS). Female ICR mice were either hindlimb unloaded or placed in the PWS system at 16% quadrupedal weightbearing for 4 h, 1, 2, 7 or 10 days, at which point complete blood counts were obtained. Control animals (jacketed and non-jacketed) were exposed to identical conditions without reduced weightbearing. Results indicate that significant changes in total white blood cell (WBC), neutrophil, lymphocyte, monocyte and eosinophil counts were observed within the first 2 days of exposure to each system. These differences in blood cell counts normalized by day 7 in both systems. The results of these studies indicate that there are some statistically significant changes observed in the blood cell counts for animals exposed to both the PWS and HU simulated microgravity systems.