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A modular and scalable Dense Medium Plasma Water Purification Reactor was developed, which uses atmospheric-pressure electrical discharges under water to generate highly reactive species to break down organic contaminants and microorganisms. Key benefits of this novel technology include: (i) extremely high efficiency in both decontamination and disinfection; (ii) operating continuously at ambient temperature and pressure; (iii) reducing demands on the containment vessel; and (iv) requiring no consumables. This plasma based technology was developed to replace the catalytic reactor being used in the planned International Space Station Water Processor Assembly.

A prototype packed bed convective dryer has been studied for use in an energy-efficient closed air-loop heat-pump drying system for astronaut cabin waste. This paper presents a transient continuum model for the heat and mass transfer between the air and wet ersatz trash in the cylindrical drying vessel. The model is based on conservation equations for energy and moisture applied to the air and solid phases and its formulation includes the unique waste characteristic of having both dry and wet solids. It incorporates heat and mass transfer coefficients for the system measured on an ersatz trash in the dryer vessel, and experimentally determined moisture sorption equilibrium relationship for the wet material. The resulting system of differential equations is solved by the finite-volume method as implemented by the commercial software COMSOL. The validated model will be used in the optimization of the entire closed-loop system consisting of dryer, condenser, and heat-recovery modules.

A Plasma Air Decontamination System (PADS) is being developed by ORBITEC for trace contaminant control in spacecraft cabin air, based on non-thermal, atmospheric pressure plasma discharges that generate various highly reactive species that can react with and break down trace air contaminants. It uses a simple and modular design, and may be scaled up or down to meet the requirements of different applications. The prototype PADS reactor has successfully demonstrated removal of ammonia and other selected volatile organic carbons from air, including acetone, ethylbenzene, methane, and methylene chloride. It has the potential to replace the existing high-temperature catalytic oxidizers.

The Biomass Production System (BPS) was flown on the ISS for 73 days as part of the Increment 4 mission. To obtain maximum benefit from the long mission duration, numerous manual crew procedures were incorporated into the BPS experiments. These procedures included gas sampling, root module priming, harvesting, pollination, filter cleaning, water refill, and water sampling. On-orbit crew assessments were filled out for each of these procedures to evaluate the ability of BPS to accommodate them. The assessment asked questions about each phase of an activity and solicited recommendations for improvements. Further analysis of most procedures was provided by detailed video made on-orbit and multiple post-flight crew debriefs. Most assessments indicated no need for improvements, but a number of crew suggestions will be incorporated into hardware and procedure updates.

The Biomass Production System, recently flown on the ISS for 73 days, demonstrated significant advancements in functional performance over previous systems for conducting plant science in microgravity. The Biomass Production System (BPS) was the first flight of a system with multiple, independently controlled, plant growth chambers. Each of four chambers was controlled separately with respect to temperature, humidity, light level, nutrient level, and CO2, and all were housed in a double Middeck locker-sized payload. During the mission, each of the subsystems performed within specification. This paper focuses on how the performance of the BPS hardware allowed successful completion of the preflight objectives.

Based upon the development experience and flight heritage of the Biomass Production System, the Plant Research Unit embodies the next generation in the evolution of on-orbit plant research systems. The design focuses on providing the finest scientific instrument possible, as well as providing a sound platform to support future capabilities and enhancements. Performance advancements, modularity and robustness characterize the design. This new system will provide a field ready, highly reliable research tool.

As space hardware continues to grow in complexity, the demands on crews expected to be able to operate and maintain this equipment continue to grow. In terms of the International Space Station, the demands on the crew have been further increased by the reduction in crew capacity from the originally planned seven members down to three. This situation has prompted the need to find new ways of training that can meet these demands. In particular, just-in-time training techniques promise to enable crew members to correctly execute procedures that they have never performed before on equipment that they are only marginally familiar with or perhaps have never even seen before. To enable crews to work with unfamiliar procedures or equipment, we believe that it is necessary to employ a highly visual approach to convey the complex spatial information that is often involved.

The Plant Research Unit (PRU) is the Space Station Biological Research Program plant growth facility being developed for the International Space Station. The plant habitat is designed for experiments in near-zero gravity or it can be rotated by the ISS Centrifuge for experiments at any gravity level from microgravity to twice Earth's gravity. Plant experimentation will be possible in multiple Plant Research Units at one time, isolating the effect of gravity on the biological specimens. The PRU will provide and control all aspects of a plant's needs in a nearly closed system. In other words, the shoot and root environments will not be open to the astronaut's environment except for experiment maintenance such as planting, harvesting and plant sampling. This also means that all lighting, temperature and humidity control, nutrient delivery, and air filtering and cleaning must be done in a very small volume, with very little mass and power usage and with minimal crew time.

The Advanced Animal Habitat (AAH) represents the next generation of Space Station based animal research facilities. Building upon previously developed flight hardware and experience, the AAH offers greatly enhanced system capabilities and performance. The design focuses upon the creation of a robust and flexible platform capable of supporting present and future experimental needs. A modular packaging and distributed control architecture leads to increased system adaptability and expandability. The baseline configuration includes group housing capability for up to six rats with automated food and water delivery as well as waste collection. Animals are continuously monitored with three cameras during both day and night cycles. The animals can be accessed while on-orbit through the Life Sciences Glovebox to perform a wide variety of experimental protocols.

The Advanced Animal Habitat (AAH) and Plant Research Unit (PRU) are two major components of the Space Station Biological Research Project (SSBRP). These two habitats are currently under development by Orbital Technologies Corporation (ORBITEC). Science Evaluation Units (SEUs) have been developed for each of these habitats to allow investigators to plan and test flight experiments on the ground using hardware that is functionally similar to the flight versions of the AAH and PRU. The SEUs also contain key functionality that makes them excellent science tools for general laboratory experiments that are not related to flight experiments.

The VEGGIE unit is a deployable, low-resource plant growth system that can provide a source of fresh food and crew recreation on long duration space missions. VEGGIE can be stowed in 10% of its deployed volume; a single middeck locker equivalent can stow 1.0m2 of growing area. To reduce complexity, VEGGIE utilizes the ambient environment for temperature control and as a source of CO2. The lighting subsystem uses LEDs that provide a minimum light level of 300 µmol m−2s−1, spectral quality control, and a long operating life in a low profile package. The root zone is a compressible fabric mat. Each VEGGIE module has 0.17 m2 of growing area and can be varied in height from 5 to 45 cm. The mass, including the lighting subsystem and root mat, is 4.7 kg. On the ISS, VEGGIE can mount in the aisle, or in an EXPRESS rack.

The ECLSS (Environmentally Controlled Life Support System) project goals are to identify key requirements and guidelines for a Life Support System (LSS) for surface missions based on the Exploration Spirals, to review the various technology options and candidates to fulfill the life support functionality, and to conduct initial trades and assessments at a high level. With the completion of the first six month phase of the project, ORBITEC has generated and shown that for each Exploration Spiral, different LSS architectures are optimal, but when an entire mission model is considered, hybrid systems become more attractive. Also, we can easily show that future spiral requirements should and will influence the technologies and level of closure for earlier spiral developments to reduce overall development and implementation costs, and to increase commonality across the Constellation systems.

The Advanced Animal Habitat (AAH) represents the next generation of Space Station based animal research facilities. Care has been taken to protect the ISS crew from exposure to the hazardous biological materials contained within the AAH. These materials include rat feces, urine, dander, and odor. The approach to containing biological materials relies on collecting the solid and liquid waste, providing physical barriers between the waste and the crew environment, maintaining negative pressure within the specimen environment with respect to the crew environment, and providing odor filtration of air exchanged between the specimen and crew environments. These protections will be in place during all modes of AAH operation.

In-situ resource utilization (ISRU) is an important part of current mission architectures for both a return to the Moon and the eventual human exploration of Mars. ORBITEC has developed and demonstrated an innovative direct energy processing approach for carbon-reduction of lunar and Martian regolith that can operate in a nearly closed-loop manner. Carbon-reduction of regolith produces oxygen and a variety of other useful products, including silicon, iron and glass ceramic materials. In addition, various ISRU propulsion technologies that utilize lunar and Martian resources have been developed and demonstrated. Work is also being conducted with the USDA on techniques to use biomass and waste materials to manufacture items such as shelters, furniture, filters and paper. Atmospheric carbon dioxide on Mars would be used to support the production of biomass in excess of life support needs to be used as the raw material to manufacture useful products on-site.

The CANDS (Circulating, Aeration, and Nutrient Delivery System) Phase II SBIR is currently developing and testing methods and procedures to control moisture, oxygen, and temperature in the root zone of a particulate based micro-gravity nutrient delivery system. The completion of the first year and a half of the CANDS Phase II SBIR has shown significant engineering developments towards environmental control of the root zone. These developments include the measurement of root zone oxygen content, characterization of forced and flood-ebb aeration rates, successful control of root zone moisture using miniature heat-pulse moisture sensors, and successful control of root zone temperature via an insulating/temperature controlling water jacket. At the conclusion of the CANDS Phase II SBIR an integrated root zone environmental control system will be constructed for integration into plant growth systems to eliminate the uncertainties that exist in current plant growth data.

A common question for students to ask educators is “When am I ever going to use this?” An excellent way to answer that question is to demonstrate how interrelated many subjects are. At ORBITEC in Madison, WI, we are developing systems to help teachers demonstrate the exciting interrelationships of science, math and technology using activities related to growing plants in space. We are developing two portable plant growth systems that integrate multiple disciplines, enriching students’ classroom experiences. Each portable growth unit is based on similar principles. The Space Garden and Biomass Production Education System (BPES) are growth units for indoor use that utilize a bellows technology to create a greenhouse-like environment. The Space Garden is a personal growth unit that a student can use individually while the BPES will be 0.25 m2, allowing larger-scale experimentation. The Space Garden will be best used in classrooms of grades four through seven.

Unique challenges arise during the design of temperature and humidity control systems (THCS) for use in microgravity. The design of the Plant Research Unit’s (PRU) THCS builds on the experience gained during the Biomass Production System (BPS) project and extends the understanding of the critical design variables and necessary technical advancements to allow for longer on-orbit operation. Previous systems have been limited by loss of prime, clogging in the porous plates and component reliability. Design of THCSs for long-duration space flight experiments requires the mitigation of these issues as well as a complete understanding of the relevant design variables. In addition to the normal design variables (e.g. mass, power, volume), a complex and interdependent relationship exists between the THCS variables including operational temperature range, operational humidity range, required humidity condensation rate and system air flow.

The objective of the BPS Technology Validation Test (TVT) flown on the ISS as part of Increment 4 was to verify the functionality of environmental control subsystems and to measure the ability of the BPS to support plant growth and development in microgravity. Additional TVT objectives included validation of information acquisition systems, operations and support systems, and component performance. All TVT objectives were successfully addressed. Most evaluation criteria stipulated pre-flight were met. When there were deviations from pre-mission requirements, root causes were identified and subsystem configurations modified to eliminate these problems. Results from the TVT have been applied to the Plant Research Unit development to reduce technical risks and increase reliability. INTRODUCTION

The design of reliable systems is especially important when they are intended for use on the International Space Station (ISS). Limits on crew time and the sensitive nature of experiments being performed require that the systems used to support those experiments have a very low probability of failure. The Plant Research Unit (PRU) has very strict reliability requirements and thus provides a good example of how the challenge of designing reliable systems can be met.

High reliability and system flexibility are driving factors in the Plant Research Unit development. Proper selection of the unit electrical and software control architecture is fundamental to achieving these goals. Key features of the PRU control design include the use of a real time operating system for main process control, dynamic power management, a distributed control architecture and subsystem modularity. The chosen approach will allow future modifications and improvements to be incorporated at the subsystem level with minimal impact to the unit overall. Hardware fault tolerance and redundancy enhance system reliability.