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This paper offers a concept for a regenerable, low-power system for purifying exhaust from a solid waste processor. The innovations in the concept include the use of a closed-loop regeneration cycle for the adsorber, which prevents contaminants from reaching the breathable air before they are destroyed, and the use of a humidity-swing desorption cycle, which uses less power than a thermal desorption cycle and requires no venting of air and water to space vacuum or planetary atmosphere. The process would also serve well as a trace contaminant control system for the air in the closed environment. A systems-level design is presented that shows how both the exhaust and air purification tasks could be performed by one processor. Data measured with a fixed-bed apparatus demonstrate the effects of the humidity swing on regeneration of the adsorbent.

A steady-state system mass balance calculation was performed to investigate design issues regarding the storage and/or processing of solid waste. In the initial stages of BIO-Plex, only a certain percentage of the food requirement will be satisfied through crop growth. Since some food will be supplied to the system, an equivalent amount of waste will accumulate somewhere in the system. It is a system design choice as to where the mass should accumulate in the system. Here we consider two approaches. One is to let solid waste accumulate in order to reduce the amount of material processing that is needed. The second is to process all of the solid waste to reduce solid waste storage and then either resupply oxygen or add physical/chemical (P/C) processors to recover oxygen from the excess carbon dioxide and water that is produced by the solid waste processor.

The current CO2 removal technology of NASA is very energy intensive and contains many non-optimized subsystems. This paper discusses the concept of a next-generation, membrane-integrated, adsorption processor for CO2 removal and compression in closed-loop air revitalization systems. The membrane module removes water from the feed, passing it directly into the processor's exhaust stream; it replaces the desiccant beds in the current four-bed molecular sieve system, which must be thermally regenerated. Moreover, in the new processor, CO2 is removed and compressed in a single two-stage unit. This processor will use much less power than NASA's current CO2 removal technology and will be capable of maintaining a lower CO2 concentration in the cabin than that can be achieved by the existing CO2 removal systems.

This paper builds on a steady-state investigation of waste heat reuse in an Advanced Life Support System (ALSS) for a Mars mission with a low degree of crop growth. In past studies, such a system has been defined in terms of technology types, hot and cold stream identification and stream energy content. The maximum steady-state potential for power and cooling savings within the system was computed via the Pinch Method. In this paper, the next step is taken toward achieving a pragmatic estimate of costs and savings associated with waste heat reuse in terms of equivalent system mass (ESM). In this paper, the assumption of steady-state flows are discarded, and a proposed schedule is developed for activities that are of interest in terms of waste heat reuse. The advanced life support system for the Mars Dual Lander Transit Vehicle is the system of interest.

Technologies that can be used to extract oxygen and other useful products from the Martian atmosphere for exploration missions will require compression of the low-pressure Martian gas. One technique that appears ideally suited for this application is temperature-swing adsorption, which can produce purified and compressed CO2 in a virtually solid-state process whose energy requirements can be met mainly through the diurnal temperature cycle. This paper focuses on material selection and sensitivity of this adsorption process to variations in Mars surface conditions. Experimental results indicate that, of the zeolite and carbon materials studied, a NaX zeolite is a superior adsorbent in terms of the amount of pressurized gas it can produce per unit mass of sorbent.

As a part of the systems modeling research at NASA Ames Research Center, the use of a market-based control strategy to actively manage power for a model of a regenerative life support system (LSS) is examined. Individual subsystem control agents determine power demands and develop bids to ‘buy’ or to ‘sell’ power. A higher level controller collects the bids and power requests from the individual agents, monitors overall power usage, and manages surges or spikes. The higher level controller conducts an ‘auction’ to set a trading price and then allocates power to qualified subsystems. The auction occurs every twelve minutes within the simulated LSS. This market-based power reallocation cannot come at the expense of life support function. Therefore, participation in the auction is restricted to those processes that meet certain tolerance constraints. These tolerances represent acceptable limits within which system processes can be operated.