Life Sciences Space Biology Project Planning

<div class="htmlview paragraph">A successful CELSS (Controlled Ecological Life Support System) design must accommodate the potential mismatch between the crew's relatively constant CO<sub>2</sub> production and the widely varying crop CO<sub>2</sub> consumption over the plant growth cycle. Any additional changes in material flows, processor characteristics or other system characteristics may have deleterious effects which propagate throughout the CELSS. Important transient conditions which the system design and planting regimen must allow for are described, including:</div> <div class="htmlview paragraph"><ul class="list disc"> <li class="list-item"> <div class="htmlview paragraph">Crop startup.</div> </li> <li class="list-item"> <div class="htmlview paragraph">Crop failures.</div> </li> <li class="list-item"> <div class="htmlview paragraph">Changes in number of humans supported.</div> </li> </ul> </div> <div class="htmlview paragraph">A general-purpose life support system simulator was used to evaluate several CELSS design and operation approaches. The simulator was used to investigate CO<sub>2</sub> generation and removal interactions occurring between the CELSS food production subsystem and the rest of the system. These interactions were selected because they are major drivers of the system design and operation.</div>

<div class="htmlview paragraph">This paper presents the basic test data obtained from tests of a cabin air distribution system in a simulated Space Station U.S. Lab-A module.</div> <div class="htmlview paragraph">The cabin air distribution system controls the flow of air in the open space of a Space Station module. In order to meet crew comfort criteria the local velocities for this cabin air are required to be distributed within a specified range with upper and lower limits. Achieving this desired velocity distribution is dependent upon the: (1.) design of the cabin air supply equipment and cabin air return equipment, (2.) total flowrate of air supplied to and subsequently returned from the cabin, and (3.) interactive effects of any other additional air flow streams which enter and exit the cabin.</div> <div class="htmlview paragraph">The basic Space Station design for the cabin air supply and air return equipment was used in this test program. Only directional adjustments to vanes in supply air diffusers were made during the test. This equipment is included in the Temperature and Humidity Control (THC) subsystem for the Space Station. Two other air streams, in addition to what is defined as THC cabin airflow, which were involved in the test program were:</div> <div class="htmlview paragraph"> <ol class="list nostyle"> <li class="list-item"> <span class="li-label">1.</span> <div class="htmlview paragraph">Standoff airflow – Standoffs are described in the paper. Briefly, they are enclosures within the cabin which formerly included ventilation fans. The consequent standoff airflow interacted with THC cabin airflow. The present baseline THC subsystem does not include the standoff fans.</div></li> <li class="list-item"> <span class="li-label">2.</span> <div class="htmlview paragraph">Intermodule Ventilation (IMV) Airflow – IMV assemblies are used to interchange airflow between Space Station modules. These modules include the U.S. Lab-A module, the nodes, and, later in the Space Station program, the international modules.</div></li></ol></div> <div class="htmlview paragraph">Test results from eight (8) of the test runs which demonstrate the ability for the air distribution system to meet its objectives are presented. These test run results are compared with each other with respect to their standing relative to meeting the test objectives.</div> <div class="htmlview paragraph">The test program investigated the effects of the variables noted above in meeting the test objectives. The basic variable in these test runs was the THC airflow. This airflow varied from 300 cfm to 500 cfm in the 8 test runs presented here. Some changes were made in supply air diffuser vane directional settings. Standoff airflow was used in one test run (number 4) and IMV airflow was used in test runs 5, 6, 7, and 8. Based on the test results, the desired velocity range and an engineering evaluation of the test results, a THC airflow rate for U.S. Lab-A is recommended.</div>

<div class="htmlview paragraph">This paper describes the results of a project involving an anaerobic digestion system used in treating the human and vegetative wastes from a Controlled Ecological Life Support System (CELSS). The anaerobic digester biologically breaks down the organic matter in the wastes into a mixture of methane gas and carbon dioxide, while significantly reducing the BOD(biological oxygen demand ) of the wastewater. A standard waste was formulated consisting of a mixture of swine waste (the surrogate for human feces and urine), green wastes (primarilly lettuce), and paper wastes. The equipment used for this project was a 2.7 cubic meter digester tank filled with plastic media and heated to an average temperature of 35°C. The digester was run over period of 200 days and loaded on the average of five days per week. The results over this test period showed a 94% reduction in BOD and a 98% reduction in suspended solids in the wastewater. Biogas production was approximately 1 cubic meter of biogas per kg of BOD added to the digester per day. This biogas contained an average of 62% methane. Tests were carried out at Lockheed in Sunnyvale to determine the effectiveness of the digester effluent as a growth medium for vegetables in a hydroponic growing system.</div>

<div class="htmlview paragraph">This paper describes the major lunar resources that would be tapped in developing a Controlled Ecological Life Support System (CELSS) greenhouse for a manned lunar base. The use of the moon's gravitational field, natural sunlight, and mineral resources from the lunar surface are discussed. Lunar soil processing technologies with CELSS relevance, and their contributions to greenhouse development are presented.</div>

<div class="htmlview paragraph">An interdisciplinary team of Texas A&M University scientists and engineers is developing concepts for controlled ecological life support systems (CELSS) employing combinations of biological, physical, and chemical components. The team includes members of several departments from the Colleges of Engineering, Science, and Agriculture. Their complementary skills are being combined to address efficient supply and recycling of food, atmosphere, water and waste products, whether for reuse in the same form, or for making materials, providing energy, or other products needed in space.</div> <div class="htmlview paragraph">Team activities produced concepts being studied in detail and technical issues being addressed by experiments in a laboratory environment. An Integrated Waste and Water Management System built by General Electric provides basic capabilities for preprocessing waste products, and for making baseline comparisons with proven physical and chemical systems. Methods being used by the team to integrate concepts and to undertake critical experiments are discussed.</div>

<div class="htmlview paragraph">Crew Health Care Systems (CHeCS) aboard Space Station Freedom will provide unprecedented on orbit capabilities targeting a wide range of nominal and contingency health concerns, from regularly scheduled exercise countermeasures and environmental monitoring, to advanced medical life support and medical transport.</div> <div class="htmlview paragraph">CHeCS design addresses unique requirements in functional performance and equipment/user interaction within the framework of physical and operational constraints imposed by the Space Station and related space vehicles.</div> <div class="htmlview paragraph">This paper presents an overview of the design and development of CHeCS for Space Station Freedom (SSF) with an emphasis on physical installation and flight crew suitability. Particular emphasis is directed at unique aspects of the system which are driven by environmental peculiarities such as limited volume and resources (electrical power, heat rejection, crew time, launch constraints), location remoteness, isolation and microgravity, while minimizing detriment to other non-related Space Station operations. Design implications resulting from phased Space Station build-up are also described. General and specific topics involve selected component and installations designs, development testing and simulation activities, and system design integration into Space Station elements. Implications introduced by CHeCS relationships to the Space Transportation System are also presented.</div>

<div class="htmlview paragraph">The Space Station Projects Office (SSPO) at NASA's Ames Research Center (ARC) is responsible for operational plans for plant and animal research in the Life Sciences Research Facility (LSRF) aboard the Space Station. As a planning database, the SSPO uses scientists' descriptions of experiment operations, configured into scenarios for typical 90-day missions. Both research tasks and tasks involving specimen care and housekeeping are included. Four of these scenarios were used to test a computer program named <i>OpSim</i>, developed by the ARC Space Human Factors Office specifically to simulate Space Station operations. The tasks for each scenario were set up for inputting to <i>OpSim</i>, simulations were executed and program output was analyzed. Some scenarios were simulated more than once, at different levels of crew time availability and of laboratory automation. The test showed that <i>OpSim</i> gives an informative picture of mission operations, and that it responds appropriately to changes in variables such as crew availability and automation. <i>OpSim</i> should become widely used to model Space Station operations and develop realistic plans.</div>

<div class="htmlview paragraph">The major goal of Space Human Factors program is to provide the technology which will enable safe and productive human performance throughout and after long duration space flights and planetary/lunar missions. The Human Factors element has three major sub-goals:</div> <div class="htmlview paragraph"> <ol class="list nostyle"> <li class="list-item"> <span class="li-label">1.</span> <div class="htmlview paragraph">Human Performance Models, Data and Tools - provide the basic understanding of human's activities in the physical, mental, and perceptual domains and to identify important lessons learned about human activities from prior space and lunar missions. To this end, Johnson Space Center is using a laser-based human body mapping system to measure different anthropometric sizes and shapes for incorporation into a large database. This database is employed, along with a spatial computer image graphics system, to analyze human motion in zero gravity conditions as the hypothetical, human bodysized figure performs a variety of new procedures in Space Station Freedom or in the Shuttle orbiter. At Ames Research Center, human performance models for computer-aided engineering, a program initially developed for aeronautical applications, are being modified for space applications. The value of the dynamic human performance models lies in the versatility in which various management decisions can be evaluated as to their impact on mission effectiveness, personnel skill and knowledge allocation, workload, workstation and cockpit design, and overall system design.</div> </li> <li class="list-item"> <span class="li-label">2.</span> <div class="htmlview paragraph">Crew Support and Enhancement - address the development of technology and its applications for the evaluation of the crew's living and working activities in the spacecraft and planetary/lunar habitat and on planetary/lunar surfaces. During the year, a number of projects were completed. At Johnson Space Center, new computer graphics were developed, particularly new methods for portraying procedures which reduce human error. Also, advances in information management methods for application to Shuttle maintenance operations were developed at Ames Research Center. Data from Kennedy Space Center operations is being used as a testbed for managing the information processing in maintenance.</div> </li> <li class="list-item"> <span class="li-label">3.</span> <div class="htmlview paragraph">Human-Automation-Robotic Systems - determine the means by which humans and automated or semi-autonomous systems can effectively work together. A major project at Ames Research Center is the development of the Virtual Workstation as a user interface device for exploring lunar or planetary surfaces. The effort this year has been to obtain a Mar-like data base and begin to employ it in simulated missions. At Johnson Space Center, effort was directed toward identifying the best location of visual sensors for teleoperations.</div> </li> </ol> </div>

<div class="htmlview paragraph">Developed as part of the suite of Space Station Biological Research Project (SSBRP) hardware to support research aboard the International Space Station (ISS), the Incubator is a temperature-controlled chamber for conducting life science research with small animal, plant and microbial specimens. The Incubator is designed for use only on the ISS and is transported to/from the ISS, unpowered and without specimens, in the Multi-Purpose Logistics Module (MPLM). The Incubator interfaces with the three SSBRP Host Systems; the Habitat Holding Racks (HHR), the Life Sciences Glovebox (LSG) and the 2.5 m Centrifuge Rotor (CR), providing investigators with the ability to conduct research in microgravity and at variable gravity levels of up to 2-g.</div> <div class="htmlview paragraph">The temperature within the Specimen Chamber can be controlled between 4° and 45<sup>o</sup>C. Cabin air is recirculated within the Specimen Chamber and can be exchanged with the ISS cabin at a rate of ≈ 50 cc/min. The humidity of the Specimen Chamber is monitored. The Specimen Chamber has a usable volume of ≈ 19 liters and contains two (2) connectors at 28v dc (60W) for science equipment; 5 dedicated thermometers for science; ports to support analog and digital signals from experiment unique sensors or other equipment; an Ethernet port; and a video port. It is currently manifested for UF-3 and will be integrated within the first SSBRP Habitat Holding Rack for launch.</div>

<div class="htmlview paragraph">The Closed Ecology Experiment Facilities (CEEF) have been under construction in northern Japan since 1994. These facilities contain the Closed Plant Experiment Facility (CPEF), as well as other facilities, in all of which, Controlled Ecological Life Support Systems (CELSS) research and development can be conducted. The CPEF includes two Plant Cultivation Modules (PCMs), which contain a PCM consists of three 30m<sup>2</sup> closed cultivation rooms illuminated solely by lamps and a 165.1m<sup>3</sup> preparation room, and a PCM consists of a 60m<sup>2</sup> closed cultivation room illuminated by natural light and supplemental lamps and a 88.8m<sup>3</sup> preparation room, and a Material Circulation System (MCS). Measured rate of air exchange between a 30m<sup>2</sup> cultivation room and the preparation room was 0.48% hour<sup>-1</sup>, and that for a 60m<sup>2</sup> cultivation room was about 0.11% hour<sup>-1</sup>. Air leak rate of the PCM as a whole was less than 0.01% hour<sup>-1</sup> under isothermal and equal pressure condition. Ethylene and isoprene concentrations in a 30m<sup>2</sup> cultivation room increased from 5nmol mol<sup>-1</sup> to 32nmol mol<sup>-1</sup> and 13nmol mol<sup>-1</sup> to 50nmol mol<sup>-1</sup> during 35 days closed rice cultivation. Accumulation of methane, NO, NO<sub>2</sub>, SO<sub>2</sub> and ammonia during the closure could not be detected and could not arouse any problem. Changes in photosynthetic CO<sub>2</sub> uptake rates of rice and soybean stands in each 30m<sup>2</sup> cultivation room with PPFD change in tiers could be monitored satisfactory using [CO<sub>2</sub>] decline rate after each intermittent CO<sub>2</sub> supply. Changes in transpiration rates of them could be monitored satisfactory using dew point difference before and after the room and air circulation rate. PPFD in 30m<sup>2</sup> cultivation rooms at the height 1.2m above cultivation beds was ca. 1.93m mol m<sup>-2</sup>s<sup>-1</sup>, when all lamps were turned on. Standard setting range of air temperature in cultivation rooms during light phase is 18 - 30 °C, but actual temperature raised from the setting point by ca. 3.4 °C, when temperature was set at 25 °C, 75% of lamps were turned on and rice (leaf area was about 3 times of the cultivation area) was planted.</div>

<div class="htmlview paragraph">Active research at the John F. Kennedy Space Center is ongoing to demonstrate the feasibility of utilizing a higher plant based engineering paradigm for advanced life support in a Controlled Ecological Life Support System (CELSS). Such a higher plant based system would ideally utilize the plants for a direct food source, for gas exchange, water reclamation and the plant residuals in a complex biological resource recovery scheme. The Kennedy system has been designed the CELSS Breadboard Project. Such an engineering paradigm utilizes a “breadboard” approach of developing independent systems that are evaluated autonomously and are later interconnected - hence the use of the “breadboard” terminology. Such a scheme will enable evaluation of an advanced life support system methodology that may have uses in a life support system for habitats as outposts on the Moon or Mars.</div>

<div class="htmlview paragraph">A Breadboard-Scale Aerobic Bioreactor (B-SAB) has been designed and integrated with the Kennedy Space Center's Biomass Production Chamber (BPC). The bioreactor utilizes a mixed microbial community to biodegrade inedible plant residues, a component of a Controlled Ecological Life Support System (CELSS) waste-stream. The continuously stirred tank reactor (120 L working volume) supports nutrient recycling and secondary food production experiments, and can process an influent with a solids loading as high as 50 g L<sup>-1</sup>. The volumetric oxygen mass transfer coefficient, k<sub>L</sub>a, is 0.013 s<sup>-1</sup>. Nutrient solution for BPC lettuce and wheat crops has been produced. Currently, B-SAB is supplying 80% of the nutrients for 10 m<sup>2</sup> of potato plants in a continuous production experiment.</div>

International audience

<div class="htmlview paragraph">Long-duration missions in space will require regenerative air revitalization processes. Human testing of these regenerative processes is necessary to provide focus to the system development process and to provide realistic metabolic and hygiene inputs. To this end, the Lyndon B. Johnson Space Center (JSC), under the sponsorship of NASA Headquarters Office of Life and Microgravity Sciences and Applications, is implementing an Early Human Testing (EHT) Project. As part of this project, an integrated physicochemical Air Revitalization System (ARS) is being developed and tested in JSC's Life Support Systems Integration Facility (LSSIF).</div> <div class="htmlview paragraph">The components of the ARS include a Four-Bed Molecular Sieve (4BMS) Subsystem for carbon dioxide (CO<sub>2</sub>) removal, a Sabatier CO<sub>2</sub> Reduction Subsystem (CRS), and a Solid Polymer Electrolyte (SPE)™ Oxygen Generation Subsystem (OGS). A Trace Contaminant Control Subsystem (TCCS) will be incorporated at a later date. Control and data acquisition for the integrated ARS is performed by a commercially available supervisory control and data acquisition system manufactured by GE Fanuc Automation North America, Inc.</div> <div class="htmlview paragraph">This paper describes the unmanned, integrated system-level ARS test that was conducted at JSC in September 1994. Descriptions of the ARS test article, the test facility, the test objectives, the test procedures, and performance results are included.</div>

<div class="htmlview paragraph">This paper contains a review of the requirements and design of the Environmental Control and Life Support System (ECLSS) for Space Station Freedom; a review of an ECLSS computer program model developed at Boeing for the complete configuration of pressurized elements or volumes; and some significant computed results from this model showing transient performance for subsystems responsible for Temperature and Humidity Control, Atmosphere Control and Supply, Air Revitalization, and Water Recovery and Management.</div> <div class="htmlview paragraph">The model referred to is a comprehensive ECLSS Model which has been developed using the G189A Environmental Control System simulation tool.(<span class="xref">1</span>)<span class="xref">*</span>. The development and potential application of the Model was presented at the 1989 ICES Conference (<span class="xref">2</span>). The Model has since been slightly revised and extensively operated, to obtain information regarding nominal and off-nominal ECLSS conditions onboard Space Station Freedom. Detailed results are presented, which include the following: 1) ECLSS conditions under nominal operation; 2)atmospheric effects of varying the crew member locations throughout Freedom; and 3)overall effects upon ECLSS of an Orbiter docking event, accompanied by changeout of the crew members.</div> <div class="htmlview paragraph">The computed results presented here are important in assessing the capabilities of the ECLSS equipment in maintaining acceptable levels of temperature, humidity, O<sub>2</sub>, N<sub>2</sub>, and CO<sub>2</sub> in the occupied volumes during crew changeout events. These events involve up to six extra crewmen from the Orbiter being located temporarily in the Space Station modules in addition to the normal contingent of eight crew members. These additional crew members impose additional demands on the ECLSS equipment, in order to control the levels of the above quantities. Satisfactory control of all off these quantities was achieved with the possible exception of the partial pressure of CO<sub>2</sub>. The maximum computed ppCO<sub>2</sub> was 4.69 mm Hg during the 107 hour long crew transfer period. This level is higher than the 3.00 mm Hg upper limit for normal conditions, but below the 7.6 mm Hg upper limit for degraded conditions. The ability of the water recovery equipment to cope with additional waste water generated and additional hygiene water used by the extra crewmen was also assessed, and was found to be satisfactory.</div>