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In a crewed spacecraft environment, atmospheric carbon dioxide (CO2) and moisture control are crucial. Hamilton Sundstrand has developed a stable and efficient amine-based CO2 and water vapor sorbent, SA9T, that is well suited for use in a spacecraft environment. The sorbent is efficiently packaged in pressure-swing regenerable beds that are thermally linked to improve removal efficiency and minimize vehicle thermal loads. Flows are controlled with a single spool valve. This technology has been baselined for the new Orion spacecraft, but additional data was needed on the operational characteristics of the package in a simulated spacecraft environment. One unit was tested with simulated metabolic loads in a closed chamber at Johnson Space Center during the latter part of 2006. Those test results were reported in a 2007 ICES paper.

Development of new air revitalization system (ARS) technology can initially be performed in a subscale laboratory environment, but in order to advance the maturity level, the technology must be tested in an end-to-end integrated environment. The Air Revitalization Technology Evaluation Facility (ARTEF) at the NASA Johnson Space Center (JSC) serves as a ground test bed for evaluating emerging ARS technologies in an environment representative of spacecraft atmospheres. At the center of the ARTEF is a hypobaric chamber which serves as a sealed atmospheric chamber for closed loop testing. A Human Metabolic Simulator (HMS) was custom-built to simulate the consumption of oxygen, and production of carbon dioxide, moisture and heat by up to eight persons. A variety of gas analyzers and dew point sensors are used to monitor the chamber atmosphere and the process flow upstream and downstream of a test article. A robust vacuum system is needed to simulate the vacuum of space.

In a crewed spacecraft environment, atmospheric carbon dioxide (CO2) and moisture control are crucial. Hamilton Sundstrand has developed a stable and efficient amine-based CO2 and water vapor sorbent, SA9T, that is well suited for use in a spacecraft environment. The sorbent is efficiently packaged in pressure-swing regenerable beds that are thermally linked to improve removal efficiency and minimize vehicle thermal loads. Flows are all controlled with a single spool valve. This technology has been baselined for the new Orion spacecraft. However, more data was needed on the operational characteristics of the package in a simulated spacecraft environment. A unit was therefore tested with simulated metabolic loads in a closed chamber at Johnson Space Center during the last third of 2006. Tests were run at a variety of cabin temperatures and with a range of operating conditions varying cycle time, vacuum pressure, air flow rate, and crew activity levels.

Under a NASA-sponsored technology development project, a multi-disciplinary team consisting of industry, academia, and government organizations led by Hamilton Sundstrand is developing an amine based humidity and carbon dioxide (CO2) removal process and prototype equipment for Vision for Space Exploration (VSE) applications. This system employs thermally linked amine sorbent beds operating as a pressure swing adsorption system, using the vacuum of space for regeneration. The prototype hardware was designed based on a two fault tolerant requirement, resulting in a single system that could handle the metabolic water and carbon dioxide load for a crew size of six. Two, full scale prototype hardware sets, consisting of a linear spool valve, actuator and amine sorbent canister, have been manufactured, tested, and subsequently delivered to NASA JSC. This paper presents the design configuration and the pre-delivery performance test results for the CAMRAS hardware.

Tests of an integrated 4-Bed Molecular Sieve Carbon Dioxide Removal System (CDRA), a Mechanical Compressor Engineering Development Unit (EDU), and a Sabatier Engineering Development Unit were conducted at NASA Marshall Flight Center in 2005 to evaluate the performance of a closed loop Air Revitalization System (ARS). A previously developed model for the integrated ARS was validated and correlated using the test data. Test data, including profiles of molecular sieve 5A bed pressure, CO2 accumulator pressure, CO2 delivery rate from the compressor, on/off operations of the compressor and relieving operation of the pressure relief valve were analyzed and compared with predictions using the integrated model. Findings from analyzing the test data, such as air leak rate to desorption beds, CO2 co-adsorption on 13X of desiccant beds, improvement in thermal modeling, etc. were reported.

The challenges of missions to the Moon and Mars presents NASA with the need for more advanced life support systems, including better technologies for CO2 removal in spacecraft atmospheres and extravehicular mobility units (EMU). Amine-coated single wall carbon nanotubes (SWCNT) have been proposed as a potential solution because of their high surface area and thermal conductivity. Initial research demonstrated the need for functionalization of SWCNT to obtain optimal adherence of the amine to the SWCNT support phase [1]. Recent efforts focus on the development of new methods to chemically bond amines to SWCNT. Synthesis and characterization methods for these materials are discussed and some preliminary materials characterization data are presented. The CO2 adsorption capacity for several versions of SWCNT supported amine-based CO2 scrubber materials is also determined.

Under a NASA-sponsored technology development project, a multi-disciplinary team consisting of industry, academia, and government organizations lead by Hamilton Sundstrand is developing an amine-based humidity and CO2 removal process and prototype equipment for Vision for Space Exploration (VSE) applications. Originally this project sought to research enhanced amine formulations and incorporate a trace contaminant control capability into the sorbent. In October 2005, NASA re-directed the project team to accelerate the delivery of hardware by approximately one year and emphasize deployment on board the Crew Exploration Vehicle (CEV) as the near-term developmental goal. Preliminary performance requirements were defined based on nominal and off-nominal conditions and the design effort was initiated using the baseline amine sorbent, SA9T.

TDA Research, Inc. (TDA) is developing a simple system that provides an effective way of interfacing the carbondioxide (CO2) removal and reduction functions. The system uses a chemical absorbent and a Sabatier catalyst combination to remove the CO2 and water vapor (H2O) produced by metabolic processes from cabin air and subsequently reduce the CO2 to methane and water. The system has the potential to weigh less than the Four Bed Molecular Sieve and CO2 Reduction Assembly combination, which is connected with a CO2 pump/compressor and storage tank due to the high CO2 absorption capacity of the sorbent and its ability to simultaneously absorb both CO2 and H2O (which eliminates the need for desiccant beds in the Four Bed Molecular Sieve System). The system does not require a CO2 pump/compressor or storage tank offering energy savings that come from effective utilization of the heat released by the Sabatier reaction to drive sorbent regeneration.

A number of amine-based carbon dioxide (CO2) removal systems have been developed for atmosphere revitalization in closed loop life support systems. Most recently, Hamilton Sundstrand has developed an amine-based sorbent, designated SA9T, possessing approximately 2-fold greater capacity compared to previous formulations. This new formulation has demonstrated applicability for controlling CO2 levels within vehicles and habitats as well as during extravehicular activity (EVA). Our current data demonstrates an amine-based system volume which is competitive with existing technologies which use metal oxides (Metox) and lithium hydroxide sorbents. Further enhancements in system performance can be realized by incorporating humidity and trace contaminant control functions within an amine-based atmosphere revitalization system. A 3-year effort to develop prototype hardware capable of removing CO2, H2O, and trace contaminants from a cabin atmosphere has been initiated.

The recovery of oxygen from a concentrated stream of carbon dioxide (CO2) offers significant advantage to long duration manned space missions by reducing the requirement for consumables. TDA Research, Inc. (TDA) has developed a chemical absorbent-based system to carry out CO2 removal and CO2 reduction for the Environmental Control and Life Support System (ECLSS) at the International Space Station (ISS). The system eliminates interfacing problems associated with the currently operational CO2 Removal Assembly (CDRA) and planned CO2 Reduction Assembly (CRA). This paper discusses the plans for TDA’s CO2 removal and CO2 reduction system. A high capacity, long-life CO2 sorbent was developed and tested under representative conditions. In addition, the performance of a state-of-the-art catalyst for CO2 reduction to water and methane at the conditions of interest was tested.

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.

An analysis model has been developed for analyzing/optimizing the integration of a carbon dioxide removal assembly (CDRA), CO2 compressor, accumulator, and Sabatier CO2 reduction assembly. The integrated model can be used in optimizing compressor sizes, compressor operation logic, water generation from Sabatier, utilization of CO2 from crew metabolic output, and utilization of H2 from oxygen generation assembly. Tests to validate CO2 desorption, recovery, and compression had been conducted in 2002-2003 using CDRA/Simulation compressor set-up at NASA Marshall Space Flight Center (MSFC). An analysis of test data has validated CO2 desorption rate profile, CO2 compressor performance, CO2 recovery and CO2 vacuum vent in the CDRA model. Analysis / optimization of the compressor size and the compressor operation logic for an integrated closed air revitalization system is currently being conducted

The International Space Station Carbon Dioxide Removal Assembly (CDRA) uses regenerable adsorption technology to remove carbon dioxide (CO2) from cabin air. CO2 product water vapor measurements from a CDRA test bed unit at the NASA Marshall Space Flight Center were made using a tunable infrared diode laser differential absorption spectrometer (TILDAS) provided by NASA Glenn Research Center. The TILDAS instrument exceeded all the test specifications, including sensitivity, dynamic range, time response, and unattended operation. During the CO2 desorption phase, water vapor concentrations as low as 5 ppmv were observed near the peak of CO2 evolution, rising to levels of ∼40 ppmv at the end of a cycle. Periods of high water concentration (>100 ppmv) were detected and shown to be caused by an experimental artifact.

To facilitate life support system loop closure on board the International Space Station (ISS), the Node 3 Oxygen Generation System (OGS) rack contains a functional scar to accommodate a future Carbon dioxide Reduction Assembly (CRA). This CRA uses a Sabatier reactor to produce water from CO2 scrubbed from cabin air and hydrogen byproduct from OGS electrolysis. As part of the effort to better understand and define the functional scar, significant risk mitigation activities have been performed. To address integration risks, a CRA Engineering Development Unit (EDU) has been developed that is functionally equivalent to a flight CRA and is suitable for integrating with ground based carbon dioxide removal and oxygen generation systems. The CRA EDU has been designed to be functionally equivalent to the Sabatier Reactor Subsystem (SRS) portion of the CRA. This paper discusses the CRA design and the major issue expected with the flight unit integration.

The recovery of oxygen from a concentrated stream of carbon dioxide (CO2) offers significant advantage to long duration manned space missions by reducing the requirement for consumables. TDA Research, Inc. (TDA) is developing a chemical absorbent-based system to carry out CO2 removal and CO2 reduction for the Environmental Control and Life Support System (ECLSS) at the International Space Station (ISS). The system eliminates the interfacing problems associated with the currently operational CO2 Removal Assembly (CDRA) and planned CO2 Reduction Assembly (CRA). This paper discusses the development efforts of a regenerable absorbent that is suitable for our conceptual system recommended for future missions. We also tested the performance of a state-of-the-art catalyst for CO2 reduction to water and methane at the conditions of interest. We demonstrate the technical feasibility of carrying out CO2 removal and reduction.

The purification of waste water is a critical element of any long-duration space mission. The Vapor Phase Catalytic Ammonia Removal (VPCAR) system offers the promise of a technology requiring low quantities of expendable material that is suitable for exploration missions. NASA has funded an effort to produce an engineering development unit specifically targeted for integration into the NASA Johnson Space Center's Integrated Human Exploration Mission Simulation Facility (INTEGRITY) formally known in part as the Bioregenerative Planetary Life Support Test Complex (Bio-Plex) and the Advanced Water Recovery System Development Facility. The system includes a Wiped-Film Rotating-Disk (WFRD) evaporator redesigned with micro-gravity operation enhancements, which evaporates wastewater and produces water vapor with only volatile components as contaminants. Volatile contaminants, including organics and ammonia, are oxidized in a catalytic reactor while they are in the vapor phase.

A thermal analysis of the compressible carbon dioxide (CO2) flow for the Portable Fire Extinguisher (PFE) system has been performed. A SINDA/FLUINT model has been developed for this analysis. The model includes the PFE tank and the Temporary Sleep Station (TeSS) nozzle, and both have an initial temperature of 72 °F. In order to investigate the thermal effect on the nozzle due to discharging CO2, the PFE TeSS nozzle pipe has been divided into three segments. This model also includes heat transfer predictions for PFE tank inner and outer wall surfaces. The simulation results show that the CO2 discharge rates and component wall temperatures fall within the requirements for the PFE system. The simulation results also indicate that after 50 seconds, the remaining CO2 in the tank may be near the triple point (gas, liquid and solid) state and, therefore, restricts the flow.

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.

This paper focuses on an Air Evaporation Subsystem component of the Water Recovery System being developed at the Johnson Space Center in the Crew and Thermal Systems Division. Specifically, the focus is on the design and testing of the next generation of Air Evaporation Subsystem Engineering Development Unit built after the Lunar-Mars Life Support Test Project Phase III 91day test. The primary objective of testing this next generation Air Evaporation Subsystem was to demonstrate its performance as a Reverse Osmosis brine treatment subsystem by looking at the condensate quality produced from Reverse Osmosis brine and the power required to process the Reverse Osmosis brine. The secondary objectives were to develop optimal operating conditions, to optimize the use of a consumable wick and to retain as much operational data as possible through instrumentation.

As part of NASA’s TransHab inflatable habitat program, a Radiation Shield Water Tank (RSWT) is being developed to provide a safe haven from peak solar particle events. The RSWT will provide an 11 ft. (3.35 m) diameter by 7 ft. (2.13 m) tall “safe haven” with a 2.26 in. (0.0574 m) thick wall of water for astronaut residence during peak solar events. The RSWT also functions as a water processing storage tank and must be capable of being filled and drained at will. Because of the unique shape of the RSWT, standard bellows and bladder designs cannot be used for inventory control. Therefore NASA has developed a bladderless tank where capillary forces govern the positioning of the liquid inventory. A combination of hydrophobic and hydrophilic membranes and wetting surfaces allows the tank to be filled and emptied as desired. In the present work, background on space-borne radiation is presented, the bladderless RSWT concept is described, and its theory of operation is discussed.