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Technologies for the recycling of water are a primary goal of NASA’s advanced life support programs. Biological processes have been identified as an attractive method for wastewater processing. A fundamental new bioreactor based on a traditional activated sludge process is demonstrated that treats hygiene wastewater using magnetic iron oxide particles agglomerated with microbial cells. In this bioreactor, microbes are suspended in magnetic flocs in a wastewater medium. Instead of a traditional gravity separator used in activated sludge operations, a magnetic separator removes the microbial flocs from the outlet stream. The reactor separation operates continuously, independent of gravitational influences. The reactor has been able to simultaneously remove 98% of high levels of both nitrogenous and organic carbon impurities from the wastewater as well as achieve acceptably low levels of total suspended solids.

A CELSS has been defined based on current or near-term technology. The CELSS was sized to support the metabolic load of four people on the Moon for ten years. A metabolic load of 14 MJ/person/day is assumed, including an average of 2.6 hr of EVA/person/day. Close to 100% closure of water, and oxygen, and 85% closure of the food loop is assumed. With 15% of the calories supplied from Earth, this should provide adequate dietary variety for the crew along with vitamin and mineral requirements. Other supply and waste removal requirements are addressed. The basic shell used is a Space Station Freedom 7.3 m (24 ft) module. This is assumed to be buried in regolith to provide protection from radiation, meteoroids, and thermal extremes. A solar dynamic power system is assumed, with a design life of 10 years delivering power at 368 kWh/kg. Initial estimates of size are that 73 m2 of plant growth area are required, giving a plant growth volume of about 73 m3.

This project investigates methods to capture an astronaut's exhaled carbon dioxide (CO2) before it becomes diluted with the high volumetric oxygen flow present within a space suit. Typical expired breath contains CO2 partial pressures (pCO2) in the range of 20-35 mm Hg (.0226-.046 atm). This research investigates methods to capture the concentrated CO2 gas stream prior to its dilution with the low pCO2 ventilation flow. Specifically this research is looking at potential designs for a collection cup for use inside the space suit helmet. The collection cup concept is not the same as a breathing mask typical of that worn by firefighters and pilots. It is well known that most members of the astronaut corps view a mask as a serious deficiency in any space suit helmet design. Instead, the collection cup is a non-contact device that will be designed using a detailed Computational Fluid Dynamic (CFD) analysis of the ventilation flow environment within the helmet.

Over the last couple decades, there has been a growing interest in incorporating commercial off-the-shelf (COTS) technologies and open standards in the design of human-rated spacecraft. This approach is intended to reduce development and upgrade costs, lower the need for new design work, eliminate reliance on individual suppliers, and minimize schedule risk. However, it has not traditionally been possible for COTS solutions to meet the high reliability and fault tolerance requirements of systems implementing critical spacecraft functions. Byzantine faults are considered particularly dangerous to such systems because of their ability to escape traditional means of fault containment and disrupt consensus between system components. In this paper, we discuss the design of a voting protocol using Time-Triggered Ethernet capable of achieving data integrity in the presence of a single Byzantine fault.

The Spacesuit Water Membrane Evaporator (SWME) is the baseline heat rejection technology selected for development for the Constellation lunar suit. The first SWME prototype, designed, built, and tested at Johnson Space Center in 1999 used a Teflon hydrophobic porous membrane sheet shaped into an annulus to provide cooling to the coolant loop through water evaporation to the vacuum of space. This present study describes the test methodology and planning to compare the test performance of three commercially available hollow fiber materials as alternatives to the sheet membrane prototype for SWME, in particular, a porous hydrophobic polypropylene, and two variants that employ ion exchange through non-porous hydrophilic modified Nafion. Contamination tests will be performed to probe for sensitivities of the candidate SWME elements to ordinary constituents that are expected to be found in the potable water provided by the vehicle, the target feedwater source.

A Total Organic Carbon (TOC) Analyzer has been developed for a Life Sciences Risk Mitigation Flight Experiment to be conducted on Spacehab and the Russian space station, Mir. Initial launch is scheduled for December 1996 (flight STS-81). The analyzer will be tested on the Orbiter in the Spacehab module, including when the Orbiter is docked at the Mir space station. The analyzer is scheduled to be launched again in May 1997 (STS-84) when it will be transferred to Mir. During both flights the analyzer will measure the quality of recycled and ground-supplied potable water on the space station. Samples will be archived for later return to the ground, where they will be analyzed for comparison to in-flight results. Water test samples of known composition, brought up with the analyzer, also will be used to test its performance in microgravity. Ground-based analyses of duplicates of those test samples will be conducted concurrently with the in-flight analyses.

A generalized computer program for analysis of pressure and composition in multiple volume systems has been under development by the National Aeronautics and Space Administration (NASA) since 1976. This paper describes the most recent developments in the program. These improvements include the expansion of the program to nine volumes, improvements to the model of the International Space Station (ISS) carbon dioxide removal system, and addition of a detailed Sabatier carbon dioxide reduction mode. An evaluation of the feasibility of adding of trace contaminant tracking was also performed. This paper will also present the results of an analysis that compares model predictions with ISS flight data for carbon dioxide (CO2) maintenance.

The Advanced Inflatable Airlock (AIA) System is currently being developed for the 2nd Generation Reusable Launch Vehicle (RLV). The objective of the AIA System is to greatly reduce the cost associated with performing extravehicular activity (EVA) from the RLV by reducing launch weight and volume from previous hard airlock systems such as the Space Shuttle and Space Station airlocks. The AIA System builds upon previous technology from the TransHab inflatable structures project, from Space Shuttle and Space Station Airlock systems, and from terrestrial flexible structures projects. The AIA system design is required to be versatile and capable of modification to fit any platform or vehicle needing EVA capability. This paper discusses the AIA conceptual design and key features that will help meet the 2nd Generation RLV program goals of reduced cost and program risk.

The development of an optimum regenerative Advanced Life Support (ALS) system for future Mars missions has been a crucial issue in the space industry. Considering the numerous potential technologies for subsystems with the complexity of the Air Revitalization System (ARS), Water Reclamation System (WRS), and Waste Management System of the Environmental Control and Life Support System (ECLSS), it will be time-consuming and costly to determine the best combination of these technologies without a powerful sizing analysis tool. Johnson Space Center (JSC), therefore, initiated the development of ALSSAT using Microsoft® Excel for this purpose. ALSSAT has been developed based upon the ALS Requirement and Design Definition Document (Ref. 18). In 1999, a paper describing the development of ALSSAT with its built-in ARS mass balance model (Ref. 21) was published in ICES.

Future spacesuits will require thermal insulation protection in low-earth orbit (LEO), in the near-earth neighborhood and in planetary environments. In order to satisfy all future exploration needs and lower production and maintenance costs, a common thermal insulation is desirable that will perform well in all these environments. A highly promising material is a fiber-reinforced aerogel composite insulation currently being developed at the Johnson Space Center. This paper presents an overview of aerogels and their manufacture, a summary of the development of a flexible fiber-based aerogel for NASA by Aspen Aerogels, Inc., and performance data of aerogels relative to flexible commercial insulation. Finally, future plans are presented of how an aerogel-based insulation may be integrated into a spacesuit for ground testing as well as for a flight configuration.

Reduction of metabolic carbon dioxide is one of the essential steps in physiochemical air revitalization for long-duration manned space missions. Under contract with NASA Johnson Space Center, Hamilton Standard is developing an Advanced Carbon Reactor Subsystem (ACRS) to produce water and dense solid carbon from carbon dioxide and hydrogen. The ACRS essentially consists of a Sabatier Methanation Reactor (SMR) to reduce carbon dioxide with hydrogen to methane and water, a gas-liquid separator to remove product water from the methane, and a Carbon Formation Reactor (CFR) to pyrolyze methane to carbon and hydrogen. The hydrogen is recycled to the SMR, while the produce carbon is periodically removed from the CFR. The SMR is well-developed, while the CFR is under development. In this paper, the fundamentals of the SMR and CFR processes are presented and results of Breadboard CFR testing are reported.

In planning for Exploration missions and developing the required suite of environmental monitors, the difficulty lies in down-selecting a multitude of technology options to a few candidates with exceptional potential. Technology selection criteria include conventional analytical parameters (e.g., range, sensitivity, selectivity), operational factors (degree of automation, portability, required level of crew training, maintenance), logistical factors (size, mass, power, consumables, waste generation) and engineering factors such as complexity and reliability. Other more subtle considerations include crew interfaces, data readout and degree of autonomy from the ground control center. We anticipate that technology demonstrations designed toward these goals will be carried out on the International Space Station, the end result of which is a suite of techniques well positioned for deployment during Exploration missions.

This paper details the analysis and design of the Temporary Sleep Station (TeSS) environmental control system for International Space Station (ISS). The TeSS will provide crewmembers with a private and personal space, to accommodate sleeping, donning and doffing of clothing, personal communication and performance of recreational activities. The need for privacy to accommodate these activities requires adequate ventilation inside the TeSS. This study considers whether temperature, carbon dioxide, and humidity remain within crew comfort and safety levels for various expected operating scenarios. Evaluation of these scenarios required the use and integration of various simulation codes. An approach was adapted for this study, whereby results from a particular code were integrated with other codes when necessary.

Recent efforts have been pursued to establish the usefulness of Space Shuttle Orbiter lithium hydroxide (LiOH) canisters beyond their certified two-year shelf life, at which time they are currently considered “expired.” A stockpile of Orbiter LiOH canisters are stowed on the International Space Station (ISS) as a backup system for maintaining ISS carbon dioxide Canisters with older (CO2) control. Canister with older pack dates must routinely be replaced with newly packed canisters off-loaded from the Orbiter Middeck. Since conservation of upmass is critical for every mission, the minimization of canister swap-out rate is paramount. LiOH samples from canisters with expired dates that had been returned from the ISS were tested for CO2 removal performance at the NASA Johnson Space Center (JSC) Crew and Thermal Systems Division (CTSD). Through this test series and subsequent analysis, performance degradation was established.

When technologies are traded for incorporation into vehicle systems to support a specific mission scenario, they are often assessed in terms of “Technology Readiness Level” (TRL). TRL is based on three major categories of Core Technology Components, Ancillary Hardware and System Maturity, and Control and Control Integration. This paper describes the Technology Readiness Level assessment of the Carbon Dioxide Reduction Assembly (CRA) for use on the International Space Station. A team comprising of the NASA Johnson Space Center, Marshall Space Flight Center, Southwest Research Institute and Hamilton Sundstrand Space Systems International have been working on various aspects of the CRA to bring its TRL from 4/5 up to 6. This paper describes the work currently being done in the three major categories. Specific details are given on technology development of the Core Technology Components including the reactor, phase separator and CO2 compressor.

This paper reviews the evolution and current state of atmospheric monitoring on the International Space Station to provide context from which we can imagine a more advanced and integrated system. The unique environmental hazards of human space flight are identified and categorized into groups, taking into consideration the time required for the hazard to become a threat to human health or performance. The key functions of a comprehensive monitoring strategy for a closed ecological life support system are derived from past experience and a survey of currently available technologies for monitoring air quality. Finally, a system architecture is developed incorporating the lessons learned from ISS and other analogous closed life support systems. The paper concludes by presenting recommendations on how to proceed with requirements definition and conceptual design of an air monitoring system for exploration missions.

Procedures that have been developed as part of the NASA JSC-sponsored pre-prototype Checkout, Servicing and Maintenance (COSM) program for pre- and post-EVA airlock operations are described. This paper addresses the accompanying pressure changes in the airlock and in the Advanced Extravehicular Mobility Unit (EMU). Additionally, the paper focuses on the components that are checked out, and includes the step-by-step sequences to be followed by the crew, the required screen displays and prompts that accompany each step, and a description of the automated processes that occur.

Automatic thermal control (ATC) was investigated for implementation into a spacesuit to provide thermal neutrality to the astronaut through a range of activity levels. Two different control concepts were evaluated and compared for their ability to maintain subject thermal comfort. Six test subjects, who were involved in a series of three tests, walked on a treadmill following specific metabolic profiles while wearing the Mark III spacesuit in ambient environmental conditions. Results show that individual subject comfort was effectively provided by both algorithms over a broad range of metabolic activity. ATC appears to be highly effective in providing efficient, “hands-off” thermal regulation requiring minimal instrumentation. Final selection of an algorithm to be implemented in an advanced spacesuit system will require testing in dynamic thermal environments and consideration of technology for advancement in instrumentation and controller performance.

Two simulated spacecraft water systems are being used to evaluate the effectiveness of iodine for controlling microbial contamination within such systems. An iodine concentration of about 2.0 mg/L is maintained in one system by passing ultrapure water through an iodinated ion exchange resin. Stainless steel coupons with electropolished and mechanically-polished sides are being used to monitor biofilm formation. Results after three years of operation show a single episode of significant bacterial growth in the iodinated system when the iodine level dropped to 1.9 mg/L. This growth was apparently controlled by replacing the iodinated ion exchange resin, thereby increasing the iodine level. The second batch of resin has remained effective in controlling microbial growth down to an iodine level of 1.0 mg/L. Scanning electron microscopy indicates that the iodine has impeded but may have not completely eliminated the formation of biofilm.

The advanced inflatable airlock (AIA) system was developed for the Space Launch Initiative (SLI). The objective of the AIA system is to greatly reduce the cost associated with performing extravehicular activity (EVA) from manned launch vehicles by reducing launch weight and volume from previous hard airlock systems such as the Space Shuttle and Space Station airlocks. The AIA system builds upon previous technology from the TransHab inflatable structures project, from Space Shuttle and Space Station Airlock systems, and from terrestrial flexible structures projects. The AIA system design is required to be versatile and capable of modification to fit any platform or vehicle needing EVA capability. During the basic phase of the program, the AIA conceptual design and key features were developed to help meet the SLI program goals of reduced cost and program risk.