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Materially-closed aquatic life support systems containing vascular plants, invertebrate animals, algae and microbes were tested in three space flight experiments with ground controls. Termed Autonomous Biological Systems (ABS), the 0.9 liter systems were completely isolated from spacecraft life support systems and cabin atmosphere contaminants, and needed minimal intervention from astronauts. The first experiment, aboard the Space Shuttle in 1996 for 10 days, was the first time that aquatic angiosperms were successfully grown in space. The second and third experiments aboard the Mir space station had 4-month durations, in 1996-97 and 1997-98, and were the first time that higher organisms (aquatic invertebrate animals) completed their life cycles in space. Compared to the ground control ABS, the flight units showed clearer water and slightly higher total organic carbon and soluble free amino acids. ABS units from all 3 flights returned as diverse and complex ecosystems.

Metabolic heat regenerated temperature swing adsorption (MTSA) technology is being developed for removal and rejection of carbon dioxide (CO2) and heat from a portable life support system (PLSS) to the Martian environment. Previously, hardware was built and tested to demonstrate using heat from simulated, dry ventilation loop gas to affect the temperature swing required to regenerate an adsorbent used for CO2 removal. New testing has been performed using a moist, simulated ventilation loop gas to demonstrate the effects of water condensing and freezing in the heat exchanger during adsorbent regeneration. Also, the impact of MTSA on PLSS design was evaluated by performing thermal balances assuming a specific PLSS architecture. Results using NASA's Extravehicular Activity System Sizing Analysis Tool (EVAS_SAT), a PLSS system evaluation tool, are presented.

The Sublimator Driven Coldplate (SDC) is a unique piece of thermal control hardware that has several advantages over a more traditional thermal control system. The principal advantage is the possible elimination of a pumped fluid loop, potentially saving mass, power, and complexity. Because this concept relies on evaporative heat rejection techniques, it is primarily useful for short mission durations. Additionally, the concept requires a conductive path between the heat-generating component and the heat rejection device. Therefore, it is mostly a relevant solution for a vehicle with a relatively low heat rejection requirement and/or short transport distances. Tests were performed on coupons and an Engineering Development Unit (EDU) at NASA's Johnson Space Center to better understand the basic operational principles and to validate the analytical methods being used for the SDC development.

Metabolic heat regenerated temperature swing adsorption (MTSA) that is incorporated into a Portable Life Support System (PLSS) is being explored as a viable means of removing and rejecting carbon dioxide (CO2) from an astronaut's ventilation loop. Sorbent pellets, which were used in previous work, are inherently difficult to heat and cool quickly. Further, their use in packed beds creates a large, undesirable pressure drop. Work has thus been done to assess the application and performance of aluminum foam that has been washcoated with a layer of sorbent. A to-scale sorbent bed, which is envisioned for use by a Martian PLSS, was designed, built, and tested. Performance of the assembly in regards to CO2 adsorption and pressure drop was assessed, and the results are presented here.

Metabolic heat regenerated Temperature Swing Adsorption (MTSA) technology is being developed to address carbon dioxide (CO2) and heat removal/rejection in a Mars Portable Life Support System (PLSS). The technology utilizes an adsorbent that when cooled with liquid CO2 to near sublimation temperatures (∼195 K) removes metabolically-produced CO2 in the ventilation loop. Once fully loaded, the adsorbent is then warmed (∼300 K) externally by the ventilation loop, rejecting the captured CO2 to Mars ambient. Two beds are used to provide a continuous cycle of CO2 removal/rejection as well as facilitate heat exchange out of the ventilation loop. To investigate the feasibility of the technology, a series of model calibration experiments were conducted which lead to the selection and partial characterization of an appropriate adsorbent.

Metabolic heat regenerated Temperature Swing Adsorption (MTSA) technology is being developed for thermal and carbon dioxide (CO2) control for a Portable Life Support System (PLSS), as well as water recycling. CO2 removal and rejection is accomplished by driving a sorbent through a temperature swing starting at below freezing temperatures. The swing is completed by warming the sorbent with a separate condensing ice heat exchanger (CIHX) using metabolic heat from moist ventilation gas. The condensed humidity in the ventilation gas is recycled at the habitat. Designing a heat exchanger to efficiently transfer this energy to the sorbent bed and allow the collection of the water is a challenge since the CIHX will operate in a temperature range from 210 K to 280 K. The ventilation gas moisture will first freeze and then thaw, sometimes existing in three phases simultaneously.

Solid Oxide Electrolysis (SOE) with an embedded Sabatier reactor is an innovative and efficient concept for regenerative air revitalization. The concept safely eliminates handling of hydrogen, and works regardless of gravity and pressure environments with no moving parts and no multi-phase flows. It also is efficient because it requires no expendables from Earth while being compact with minimal impact on mass. The consequence is significant because SOE is an inherently suitable technology (and possibly the only technology) for enabling 100% oxygen regeneration from carbon dioxide and water vapor, two byproducts of crew activity that must be managed. To investigate the feasibility of this concept, a Sabatier reactor was successfully embedded into a single SOE cell.

Paragon Space Development Corporation has created the only privately developed and owned Environmental Control and Life Support Systems Human-rating Facility (EHF) for spacecraft ECLSS system testing in a dynamic flight environment. The facility allows for simulating the very stressing dynamic changes in pressure, altitude and operating conditions for human spaceflight, including suborbital and orbital flight profiles as well as Mars and lunar environments. Testing of space suits, pressure suits and ECLS systems can be performed for failure scenarios not able to be duplicated during flight testing. The facility allows for testing of ECLSS hardware before integration with the spacecraft, lowering ECLSS development cost and time, thereby reducing program risk. This paper describes the detailed design and setup of the EHF as well as the various capabilities.

The Sublimator Driven Coldplate is a unique piece of thermal control hardware that has several advantages over a traditional thermal control scheme. The principal advantage is the possible elimination of a pumped fluid loop, potentially saving mass, power, and complexity. Because this concept relies on evaporative heat rejection techniques, it is primarily useful for short mission durations. Additionally, the concept requires a conductive path between the heat-generating component and the heat rejection device. Therefore, it is mostly a relevant solution for a vehicle with a relatively low heat rejection requirement. This paper describes the design of an engineering development unit intended to demonstrate the feasibility of the Sublimator Driven Coldplate concept.

A phase change material (PCM) heat sink using super cooled ice as a non-toxic, non-flammable PCM is being developed for use in a portable life support system (PLSS). The latent heat of fusion for water is approximately 70% larger than most paraffin waxes, which can provide significant mass savings. Further mass reduction is accomplished by super cooling the ice significantly below its freezing temperature for additional sensible heat storage. Expansion and contraction of the water as it freezes and melts is accommodated with the use of flexible bag and foam materials. A demonstrator unit has been designed, built, and tested to demonstrate proof of concept. Both testing and modeling results are presented.

Patent-pending Metabolic heat regenerated Temperature Swing Adsorption (MTSA) technology is currently being investigated for removal and rejection of carbon dioxide (CO2) and heat from a Portable Life Support System (PLSS) to a Martian environment. The metabolically-produced CO2 present in the ventilation loop gas is collected using a CO2 selective adsorbent that has been cooled via a heat exchanger to near CO2 sublimation temperatures (∼195 K) with liquid CO2 (LCO2) obtained from Martian resources. Once the adsorbent is fully loaded, used, warm (∼300 K), moist ventilation loop gas is used to heat the adsorbent via another heat exchanger to reject the collected CO2 to the Martian ambient. Two beds are used to achieve continuous CO2 removal by cycling between the cold and warm conditions for adsorbent loading and regeneration, respectively.