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The Oxygen Generator Subsystem (OGS) on the next Mars Lander will demonstrate the production of oxygen from Martian atmospheric carbon dioxide using solid oxide electrolysis. The electrolyzer in OGS is based on a Yttria Stabilized Zirconia electrolyte and operates at 750°C. The electrolyzer is thermally cycled during every sol of operation between Mars ambient and operating temperature with a maximum of 15W electrical power. A package for this electrolyzer has been designed, built, and tested. It meets all the requirements of this experiment and weighs only slightly more than 1kg.

This paper will summarize the goals and key findings of a workshop held at the NASA Ames Research Center in June 1998 on the subject of piggyback mission opportunities and Technology challenges for Astrobiology missions. The first goal of the workshop was to identify and characterize piggyback mission opportunities in the years 2000 to 2006. The opportunities were to include the various planetary spacecraft that are slated to be launched within our solar system with special emphasis on Mars and Europa, the opportunities that exist in Low Earth Orbit with emphasis on the STS missions and Space Station, ground based opportunities, and commercial flight opportunities. The second goal was to identify the technology needs for Astrobiology, catalog the state of the art technologies and their adequacy to answer the critical questions, and list the key areas that would require immediate technological investment and development.

This paper describes a simple concept for extracting a nitrogen-argon carrier gas mixture from the Martian atmosphere in-situ and compressing the gas to a pressure suitable for use in analytical experiments during exploration missions. Both the separation and compression processes are performed via adsorption. In addition to being a low-mass, low-volume, and virtually solid state unit, the process consumes little or no electrical power. Energy to perform work is taken from the environment using the daily temperature cycle. Such a device would also be a proof-of-concept technology for buffer gas generation for life support application on future human missions to Mars.

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.

This paper explores the possibilities of cooling a permanently inhabited lunar base with a reverse Brayton cycle Thermal Control System (TCS). Based on an initial stage outpost, the cooling needs are defined. A thermodynamic performance model for the Brayton cycle is derived using ideal gas analysis. This model includes inefficiencies and irreversibilities of the components. The free parameters in the thermodynamic model are successively removed using limiting values for efficiencies and determining operating parameters by suboptimizations. In essence a model for cooling efficiency as a function of rejection temperature alone is obtained. For every component of the system a mass model is applied and the overall mass is determined. The last remaining degree of freedom, the rejection temperature, is eliminated by an optimization for lowest overall mass. The result for minimal TCS mass is compared to a reference TCS using a Rankine cycle.

A parametric analysis is performed to compare different heat pump based thermal control systems for a Lunar Base. Rankine cycle and absorption cycle heat pumps are compared and optimized for a 100 kW cooling load. Variables include the use or lack of an interface heat exchanger, and different operating fluids. Optimization of system mass to radiator rejection temperature is performed. The results indicate a relatively small sensitivity of Rankine cycle system mass to these variables, with optimized system masses of about 6000 kg for the 100 kW thermal load. It is quantitatively demonstrated that absorption based systems are not mass competitive with Rankine systems.